Richard Harwood and lan Lodge Cambridge IGCSE® Combined and Co-ordinated Sciences Chemistry WorkbookCAMBRIDGE UNIVERSITY PRESS University Printing House, Cambridge CB2 8BS, United Kingdom One Liberty Piaza, 20th Floor, New Yotk, NY 10006, USA 47 Williamstown Road, Port Melbourne VIC 3207, Australia 4843/24, 2nd Floor, Ansari Road, Daryagani, Del 9 Anson Road, #06-04/06, Singapore 073905 = 110002, india Cambridge University Pressis part ofthe University of Cambridge. \tfurthers the University’s mission by disseminating knawledgein the pursuit of education, learning and research at the highest international levels of excellence. wwwcambridge.org Information on this title: worw.cambridge.org/S781316631058 (© Cambridge University Press 2017 ‘This publication isin copyright. 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C7 How far? How fast? 1. Terms of reaction 02 Energ diagrams €704 The influence of surface area on the rate of reaction C705 Finding the rate of a r producing @ ge 7.06 Runaway reactio C8 Patterns and properties of metals 801 Gro up|: The alkali metal €8.02 The reactivity series of met. 8.03 Energy from displacement reactions €8.04 Metals and alloys C9 Industrial inorganic chemistry 50Seon 902 Extracting aluminium by electroly 81 C11 Petrochemicals and polymers 108 9.03 The importance of nitrogen 92 C1101 Essential processes of the C9.04 Makingsulfuric acid industrially 95 Petrochesnical Industry " C1102 Addition polymerisation 10 305 Concrete chemist 96 03 Representing condensation 9.06 The chlor-alkali industry 98 oWTIRTERtOA reactions m C10 Organic chemistry 100 ing fuel demand C1001 Families of hydrocarbons 100 €12 Chemical analysis and investigation 114 10.02 Unsaturated hydrocarbons 1201 Chemical analysis 4 the alkenes 101 12.02 Chemical testing and evaluation €10.03 The al as fuels 03 1008 The f \ 12.03 Experimental design 10.04 Hydrocarbons and their eactions 106 Answers 125Introduction This workbook covers two syllabuses: Cambridge IGCSE Combined Scien Cambridge IGCSE Co-ordinated Sciences (0654). Before you start using thi heck with your teacher which syllabus you are studying and which papers you will take, You will sit either the Core paper or the Extended paper for your syllabus. If you are sitting the Extended paper, you wil 1udy the Core material and the Supplement material for your syllabus ce you know which paper you willbe sitting, you can use the exercises in this workbook to help develop the skills you need and prepare for your examination, ests three different vent Objectives, oF AOs for short. These are understandi 02 Handling information and problem solving 03 Experimental skills and investigations. git is therefore not enough to make sure u get the bes narks are for AO2 and AOS, You need to be able to use w ‘and to demonstrate your experimental skills (403). re are lots of activities in your coursebook which will help you to de imental skills by d al work. This workbook contains exercises to help you to develop AO2 and AOS furthe There are some questions that just involve remembering things ‘aught (AOL), but most ne questions require you to use what you've learned tow 2 exercise: to be exactly like the questions you will get on your exam papers, lp you to develop your skills, rather than testing you on the p yo p 2 of each exercise that tells you the purpose of it essment checklists. You can try usir emember the importa about. Your teacher sho Iso mark the work and will discuss with you whether your own as nts are right his will help you gins of the b that everyorTe ae ee eT Cambridge IGCSE Combined You will study the ater Without a Without a sidebar sidebar With a double grey sidebar ith ado black sidebar Cambridge IGCSE Co-ordinated Sciences (0654) Core Without a sidebar ha single grey sidebar With a double grey sidebar Ercan’ You will study everything, Without a assingle With a double grey sidebar With a single blacksideba With a doublewe | wo | wy | ne | ew | on |e | a |v ven a | po | om | us | wa | pw | 4s | o> | mr somes | £4-[0 2 dala x bole odoin s fale af maa aT oo tap The Periodic TablePlanet Earth sch ran: rainfll wih pH usually ee than res teem a on ee a ‘photosynthesis: the photochemical reaction in the green leaves of plants thattums carbon dioxide ‘and waterintogluccee and oygen esplaton the biochemical eactionin ving cals that produces energy om the reaction of _lucose and eaygen to produce carton dioxide and water Exercise C1.01 Global warming and the ‘greenhouse effect’ This exercise will help in developing your skills at processing unfamiliar data and making deductions from novel sources. Describe the process of photosynthesis in simple terms.ee TET Global warming: Since the burning of fossil fuels started to increase in the late nineteenth century, the amount of carbon dioxide in the atmosphere has increased steadily. The changes in the mean temperature of the Earth have not been quite so regular. Below are some data regarding the changes in mean temperature of the Earth and ‘amount of carbon dioxide in the atmosphere. Table 1.01 gives the changes over recent years, while Table 1.02 gives the longer-term changes. The mean temperature is the average over all parts of the Earth's surface over a wh year. The amount of carbon dioxide is given in ppm (parts of carbon dioxide per milion parts of ar Ce ene ad 1982 340 1880 291 ___ 1392 1984 343, 1890 204 | 1381 1986 347. 1900 297 13.95) 1988 351 1910 300 1380 1990 354 1920 303 3.82 1992 356 1930 306 1396 1994 358 1940 309 1414 1996 361 1950 312 13.83 1998 366 1960 317 13.99 2000) 369 1970 324 1404 {2002 373 1980 338 1428 2004) 990 354 14.48 2006) 381 2000 369 14.39 2008 385 [2010 390 14.69 Zon ea Table 1.02 2012 394 2014 395, 2016) 401 Table 1.01 Plot these results on the grid provided using the left-hand right-hand y-axis for mean temperature. Draw two separat (Use graph paper if you need a larger grid. amount of carbon dioxide and the graphs to enable you to compare the trends ‘© What do you notice about the trend in amount of carbon dioxide? hat do you notice about the trend in mean temperature?Chapter C1: Planet Earth .™ - 7 i 150 3 370 M46 5 350. 4.2 the graph clearly show that an increase in carbon dioxide is causing an increase in temperature? Estimate the amount of carbon dioxide in the atmosphere and the likely years 2020 and 2040, temperature of the Earth in the Between the eleventh century and the end of the eighteenth century the amount of carbon dioxide in the atmosphere varied between 275 and 280 ppm. Why did it start to rise from the nineteenth century onwards. Other ‘greenhouse gases’ are present in much smaller amounts, However, they are much more effective ‘at keepingiin heat than carbon dioxide. Methane (1.7 ppm) has 21 times the effect of carbon dioxide. Nitrogen oxides (0.3 ppm) have 310 times the effect of carbon dioxide Name a source that releases each of these gases into the atmosphere, Met! ne: Nitrogen oxides:,,Perr a cette Tit Use the checklist below to give yourself a mark for your graph. For each point, award yourself: + 2marks if you did it really well + Lmark if you made a good attempt at it, and partly succeeded + Omarks if you did not try to do it, or did not succeed. Self-assessment checklist for graphs: enn eee a acs ‘You have plotted each point precisely and correctly for both sets of data - using the different scales on the two vertical axes, You have used a small, neat cross or dot for the points of graph, You have us or small, but different, symbol for the points ofthe other graph. You have drawn the connecting lines through one set of y~ using a ruler forthe lines. points accural the connecting lines through the other set of points accurately - using a different colour o broken ine You have ignored any anomalous results when drawing |: | the lines. Total (out of 12) 10-12 19 4-6 need to improve quite a 23 ph again, using ane 1 ‘ough all the criteria again, and then try the same graph again.Pegee a) Exercise C1.02 Atmospheric pollution, industry and transport This exercise discusses different aspects of atmospheric pollution and relates it to key aspects of human activity. It will help you in developing your skills in evaluating data and drawing conclusions from them. The following pie charts show estimates of the sources of three major atmospheric pollutants in an industrialised country. transport industria industria sae wteopn home heting dioxide one transpor power station others home heating carbon 9% power stations monoxide ee a Whats the lar urce of sulfur dioxide pollution? b_ Name the three ma 10Se combustion gives rise to the levels of sulfur dioxide in the atmospher © Units are being added to the some power stations and industrial plants to prevent the emission of sulfur dioxide Whats the name given to these units? Nitrogen oxides (NO,) a other major pollutant ofthe atmosphere, particularly in large cities, 1 Nitrogen monoxide is formed by the reaction of nitrogen and oxygen inside the hot engine of cars and other vehicles. Complete the following equation for the reaction producing nitrogen monoxide Ne#0:-%.....NOi When leaving the car, nitrogen monoxide in the exhau produce the brown gas which can be seen in th Balance the equation for the production of this gas. ‘umes reacts fur imosphere over la with oxygen in the airto cities nitrogen monoxide + xygen—> nitrogen dioxide NO +O > NO, iii The operating temperature of a diesel engine i significantly higher than that ofa petrol (gasoline) engine Would you expect the level of NO, emissions from a diesel-powered vehicle to be greater or lower than from a petrol-powered vehicle? Give the reason for your answer tted to modern cars to redu s of nitrogen? he level of pollution by Nitrogen oxides, unburnt hydrocarbons and carbon monoxide combine together under the influenc ultraviolet light to produce photochemical smog. y do you think this form of pollution is most common in large cities? ‘ther form of pollution from car exhaust fumes has now almost totally disappeared from modern ties follow ges in fuel and pollution monitoring? der to control traffic flow, London introdu 103. Table 1.03 shows figures for the percentage fallin the levels of certain pollutants following introduction of the congestion charge. da ‘congestion charge’ for vehicles entering the cen Pollutant gas within Congestion Charge Zone traffic emissions change 2003 2002 /% _ (Overall traffic emissions change 2004 versus 52 09 2003 /% Change due to improved vehicle technology, “173 34 2003 to 2006 /'% Table 1.03 i What was the measured percentage drop in the level of nitrogen oxides within the Congestion Cha fer the first 2 year jowing the introduction of the charge!Cea tau) At face value there seems to be a drop in the levels of pollutants following the introduct ‘congestion charge. But should we expect the fal in pollution levels to continue? An independent study published in 2011 suggested that other factors should be taken into account, particularly when trying to study a relatively small area within a large city, One factors hinted at in the third row of figures. Whatis that factor, and what other influences need to be taken into account in considering ths situation? g Theuse of fossil fuels in industry and transport also produces carbon dioxide. What is the reasoning behind the slogan painted on these freight containers seen waiting to be loaded on to a freight train outside a major UKsstation? Outline the argument behind the slogan,This exercise covers aspects of how we produce clean water for domestic and industrial use, focusing on stages that depend on key physical and chemical techniques. The provision of clean drinking water and sanitation to more of the worle's po millennium goals of the United Nations. The lack of this basic provision impacts not an area, in particular the mortality rate of children, but also on the level of e ‘ommunity The diagram shows the different stages inv ndustral use, din a modern water plant producing tet for domestic and as river water pumping. _storage reservoir “a . tweoted witha small rain ozone chlorine caeee, microsteainers ‘activated carbon @)_themaincose sranules absorb Y of ozone toaniise inking wate service reservoir hat devices are used in the early stages of processing to remove insoluble debris and material Include comments on the size of the material removed by these methods. 1b Whatis the common purpose of treating the water with chlorine and/or ozone? © What other purpose does treatment witor ciaetal 1d What type of chemical agent is ozone (0,) behaving asiin the reactions invalved in part ¢? ‘© Countries that have insufficient rainfall, or where water supply isin great demand, may need to use other methods of producing clean water. Here, processes for desalination are used i What does the term ‘desalination’ mean? ii Name two methods that such countries use for desalination. iil Giveone disadvantage of these methods of desalination, f Tapwater produced by a water treatment plant such as shown in the diagramis clean, butitis not pure. It will contain metal and non-metal ions dissolved from the rocks that the rivers and streams flowed over, i Chloride ions are present in tap water. Describe a chemical test that would show the presence of loride ions (CI in the water, Describe the test and what would be observed ii Oneof the chlorides often present in tap water is sodium chloride. Give the word and balanced symbol equation for the reaction taking place in the test you have described above, sodium chi Nac em => " ili Givethe ionic equatThe nature of matter Exercise C2.01 Changing physical state This exercise will develop your understanding of the kinetic model and the energy changes involved in changes of physical state. The graph shows the heating curve for a pure substance, The temperature rises with time as the substance s heated a What physical state(s) is the substance in at points, B, Cand D? A 8 c > Temperature /°Cers b_ Whatis the melting point of the substan © Whats ts boiling point? 4. What happens to the temperature while the substance is changing state The substance is not water. How do we know this from the graph? Complete the passage using the words given below. different diffusion gas spread particles diffuse random lattice vibrate temperature The kinetic model states that the in aliquid anda areinconstant motion Ina gas, the particles are far apart from each other and their motion is said to be The particles in a solid are held n fied positions in a regular Ina solid, the particles can only, about their fixed positions. Liquids and gases are fluid states. When particles move in a fluid, they can collide with each other. When they collide, they bounce offeach otherin directions ftwo gases or liquids are mixed, the different types of particle ‘out and get mixed up. This process is called Atthe same. particles that have a lower mass move faster than those with higher mass This means that the lighter particles will spread and mix more quickly; the lighter p: es aresaid to faster than the heavier particles. 1B Use the data given for the substances listed in Table 2.01 to answer the questions that follow on their state at a room temperature of 25°C and atmospheric pressure, point /°C Coens 98 883 “a “62 78 2900 =196 propane ~42 ethanoic acid 16 18 Table 2.01i Which substance is aliquid over the smallest range of temperature?., i Which two substances are gaseous at -50°C?, and ii Which substance has the lowest freezing point? iv Which substance is liquid at 2500 °C? V__ Asample of ethanoic acid was found to boil at 121 °C at atmospheric pressure. Use the informa the table to comment on this result. Exercise C2.02 Plotting a cooling curve This exercise presents data obtained practically for plotting a cooling curve. It will help develop your skills in handling the data and interpreting what changes the different regions of the curve represent. Examples of sublimation are also discussed. Astudent carried out the following data-logging experiment using apparatus shown in the following diagram as part of a project on changes of state. An organic crystalline solid was melted by placing it in a tube in a boiling || water bath. A temperature sensor was placed in the liquid. thot boiling water The temperature change was followed as the liquid was allowed to cool down. The data shown in Table 2.02 are taken from the computer record of the temperature change as the liquid cooled down to room temperature peal o| os] 10] 15] 20 24] 26 30] 35] 40] 4. Acaemmmumtel 26-1 [£92 [852 [820] 809] 807 [06 [aos [aos [eos | 784 |742| eas | aro Table 2.02Chapter C2: The nature of matter On the grid provided, plot a graph of the temperature change taking place in this experiment. hange is taking place over the second minute of the experiment? © Why does the temperat what is happening to th re remain almost ve your explanation in terms of stant over this period of tim 1e organisation of the molecules of the substance, ‘d_ What change would need to be made to carry out the experiment using a compound with a melting point fer than 100°Ceat RE Reet @- Asimilar experiment was carried out to demonstrate th ling curve for paraffin wax. 1 Inthe space below, sketch the shape of the graph you would expect to produce. Explain why the curveis the shape you have draw £ Sublimation occurs when a substance passes between the solid and gaseous states without going through the liquid phase. Both carbon dioxide and water can sublime under certain conditions of temperature and o || pressure. Dry ice’ the solid form of carbon dioxide used in commercial refigeration. At atmospheric pres: ‘sublimation point’ of -78.5°C ithasa i What difference can you see between solid ¢: atmospheric pressure? dioxide and water ice at li fyou gently shake a carbon dioxide fire extinguisher as seen in the diagram, vill feel the presence of liquid within the extinguisher. What conditions within inguisher mean that the CO, is liquid in iii Complete the following paragraph about a p: 1 type of frost using the words listed below. surrounding liquid colder humid white crystals ice Hoar frost isa powdery frost caused when solid rms from, air, The solid surface on which its formed must be Nase air Water vapour is deposited on a surface as fine ice without going through the. phase.Exercise C2.03 Diffusion, solubility and separation The processes of diffusion and dissolving in a solvent are linked. This exercise explores the basis. of these processes in terms of the kinetic (particle) theory. The separation of a solvent mixture by fractional distillation is discussed. Astudent placed some crystals of potassium manganate(u) at the bottom of a beaker of distilled water. She then leftthe contents of the beaker to stand for Lh, ‘a. The diagram below shows what she saw during the experiment. After 1h, all the solid crystals had disappeared and the solution was purple throughout. distiled water { purple crystals ~ atstart ater 15min aera i Usethe ideas of the kinetic theor servations. explain Jif warm water at 50°C had been used, would the observations have taken place ina longer or shorter time? Explain your answer. b_ The process of dissolving can be used to separate and purify chemical compounds. Organic solvents such {8 propanone can be used to extract pigments from plants. Some grass is crushed and mixed with the propanone. The colour pigments are extracted to give a dark green solution, i Given a pure sample of chlorophyll, describe how could you show that the green solution from the £rass contained chlorophyll and other coloured pigments?E Combined and Co-ordinated Sciences Draw a labelled diagram that describes the method of separating coloured pigme discussed in parti at you have Use the checklist below to give yourself a mark for your drawing. For each point, award yourself: + 2marks if you did it really well + 1markif you made a good attempt atit, and partly succeeded ‘+ Omarks if you did not try to do it, or did not succeed. Self-assessment checklist for drawings: Check point Cer You fore You have made a large dr ng, using the space provided, There are no obvious errors - liquids missing, flasks open when they should be closed, etc. You have drawn single lines with a sharp pencil, not many tries at the same line (and erased mistakes). You have used a ruler for the lines that are straight Your diagram is in the right proportions, You have drawn label lines with a ruler, touching the item being labelled. have written the labels horizontally and neatly way from the diagram itself. Total (out of 14) 12-14 Excellent 10-11 Good, cz) 5-6 tart, but you need y this same drawing agai usinga pap 1-4 Very poor. Read through ll the criteria again, and then try the same drawing.er cee aie aa Iii Explain the role of chlorophyll in the leaves of green plants, € Propanone is a very useful solvent that mixes » I with water even though itis an organic compound. ‘Apropanone: water (65% : 35%) mixture used for cleaning laboratory apparatus can be separated using fractional distillation. Atotal volume of 80cm? of the mixture was distilled ‘Sketch below a graph of the temperature readings against the volume of distillate collected for the distillation carried out. The thermometer s placed at the connection between the fractionating column and the condenser, The boiling point of propanoneis $6 °C.ec EG Rem EET Exercise C2.04 Chromatography at the races This exercise will help you understand aspects of chromatography by considering an unfamiliar application of the technique. test for the prese ilegal drugs it Chromatography is used by the ‘Horse Racing Forensic Laborato racehorses. the start line. Alongside this, kn When finished, the paperis read by diagram Aconcentrated sample of urine is spotted on to chromatography papero drugs are spotted. The chromatogram is run using methanol as the solver placing it under ultraviolet light. A chromatogram of urine from four racel and details are included in Table 2.03. Fes is Shown in the follow! es °° [2 [paracetamol . ° [3 Turine sample hor ‘ 4_| urine sample horse B athe [6 Taurine sample horse D re Table 2.03 ors which determine the distance a substance travels up the paper. b The results show that the sample from one horse contains an illegal substance, State which horse and the drug that is present a reason for the use of this drug. d_ The results for known drugs are given as 'R, value ravelled by the subs travelled by the sol culate the R, value for caffeineRe ear Exercise C2.05 Atomic structure This exercise helps familiarise you with aspects of atomic structure including the organisation of electrons into energy levels (or shells), and the uses of radioactivity. ‘a Choose from the words below to fil in the gaps in the passage. Words may e used once, more than once or not ata proton electrons nucleon isotopes neutrons nucleus energy levels protons ‘Atoms are made up of three diferent particles: which are positively charged; which have no charge; and which are negatively charged, The negatively charged particles are arranged in different (hells) around the ofthe atom. The particles with a negligible mass are the All atoms of the same element contain the same number OF sentneeee snes NO on _.cAtoms of the same element with diferent numbers of known as b This part of the exercise is concerned with electron arrangements and th Complete these sentences by filling in the blanks with words or numbers. ucture of the Periodic ble, nn . | + upto electronsin the third shel There are 8 electrons in total when the three shells are completely full) The elements in the Periodic Table are organised in the same way as the electrons fill the shells. Shell fill from, to. across the ofthe Periodic Table. +The first shell fils up first from to helium. 1 second shell ills next from lithium to + Eight seu B0 ito the third shell from sodium to argon, + Then the fourth shell starts to fil from potassium.€ In 1986, an explosion at Chernobyl in the Ukraine released a radioactive cloud containing various radioactiv ee such isotopes are mentioned in Table 2.08, Use your Periodic Table to nswer the following questions about them Coan es strontium 90 = iodine 131 cae’ 137 Table 2.04 i How many electrons are there in one atom of strontium-90 fi Howmany }erein one atom of iodine-131? How many neutrons are there in an atom of caesium-137?, Exercise C2.06 Influential organisation This exercise explores how that structure influences the major properties of the atoms of an element. Ba hat atom, Whether an atom isracioactive, the type of bond it makes, its chemical reactivity anit pstion nth 4,can be of use in biochemical and medical research. d by scientists to track the synthesis and use of compound: elements, such as carb they can be us a Isotopes of cert Because they are radioacti mportant in the chemist deductions from the 1 Complete Table 208 some common elements, makin give ement, the second isotope is a radioisotope used in research Boca Creer [te ora rae hydrogen (tritium | q | iodine Table 2.05Re uC cy li Researchers are able to use these radioisotopes to study the chemistry of cells because these atoms have the same chemical properties as the non-radioactive atoms. Why are the chemical properties ofall Isotopes of the sameelement identical? he at mic structure of five atoms, A, B, €, D and E, (Note that these letters are J] © Thetable below gives details of || not their chemical symbol | Complete Table2 Table 2.06 1 How many of these atoms are of elements in the secor d period of the Periodic Table? li Which two atoms belong to elements in the same group? Iii How many electrons does atom C have which uid be involved in chemical b nding? am to sh he arrangement of the electrons in atom D.Elements and compounds Qo ‘temvent: a substance contaningonly oe type of atom compound: a substance made of two, or more, elements chemically combined together ‘periodic table: the table in which the elements are organised in order of increasing proton number ~andelectron arrangement ‘group: a vertical column of elements nthe Periodic Table; elements nthe some group havesimlar Properties pried: 2 horizontal row of elementsin the Periodic Table ESA a Exercise C3.01 Periodic patterns in the properties of the elements This exercise will help your understanding of the periodic, or repeating, patterns shown by the elements. It will also support your understanding of the structure of the Periodic Table in groups of elements and help you begin to predict properties within these groups. ble is thChapter C3: Elements and compound: {a Fillin the symbols and proton numbers missing from the boxes on the cl seven proton numbers) ‘above (seven symbols and Which two ele nents are at the peaks of the chart? € Towhich group do these two elements belong?, d_Thehalogens are one group of elements in the Periox halogens by crossing out the incorrect bold words. e. Complete the following statements about the + Thehhalogens are metals / non-metals and their vapours are coloured / colourless + The halogens are toxie / non-toxic to humans, gen molecules are each made of one / two atoms; they are monatomic / diatomic fens react with metal / non-metal nts to form crystalline compounds that are salts + The halogens get more / less reactive going down the group in the Periodic Table. + Halogens 1n colour / bleach vegetable dyes and kill bacteria, Elements within a group tend to show clear trends in their ph The following solid elements in Group Vi show this. Complete Table 3.01 by fil values when filling in the missing values, 685 4q9 0.198 450 0.221 al properties as you go down a group. aps. Use the following [eas selenium tellurium Cee area) 624 font ea 2 Peart: 988 eee ea) J Table 3.01Exercise C3.02 The first four periods ‘This exercise is aimed at developing your knowledge of the basic features of the Periodic Table and the properties of an element that relate to its position in the table, The diagram below shows the upper part of the Periodic Table with certain elements selected JI *|* ve, write down the symbols fr Using the elements shown ab the elements which answer the fo a Which two ements are stor under oll because they are very reactive? Which tw sments are transition met € Which element has just two electronsin the full outer shell ofits atom? _ Which elementis a red-brown liquid at room temperature and pressure? @ Which element has four electrons in the outer energy level ofits atom? £ Which elementis a yellow solid at room temperature? & Which elements are noble gases? thas compound: produce blue solutions when they dissolve? i Which elementhas the elect angement 2.8.8.2? J Which element burns with a brilliant white flame when ignited?ee Reta TT Exercise C3.03 Trends in the halogens This exer #¢ examines the trends in physical properties of elements within a non-metal group of the Periodic Table. It should help you develop your skills at analysing and predicting trends within a group. Table shows some of the physical pr ties of the elements of Group VIl at atmospheric pressure. These elements are known as the halogens and the properties show distinct trends as you go Pao on fluorine 9 pale el chlorine =101 4 pale gre bromine 35 6 iodine 33 4 185 srey-black astatine 85 303 337 Table 3.02 graph of the melting points and boiling points ofthe hal ens against their proton numbers in the gre Provided. Join the points for each property together to produce two separate lines on the raph. Draw a line across the graph at 20°C (room temperature) to help you decide which elements are solid, quid or gas at room temperature and pressure.ens b_ Use your graph toest nate the boiling point of bromine, and state its colo ‘and physical state atroom temperatu Estimated boiling point "c Colour Physical state: J] © Which of the halogens are gases at room temperature and pressure | d_ Astatineis very rarely seen. What would you predict to be its physical state and colour at room temperatu and pressure? @ Whats the trend observed in the melting points of the halogens as you go down the group? Exercise C3.04 The chemical bonding in simple molecules This exercise will familiarise you with the structures of some simple covalent compounds and the methods we have for representing the structure and shape of their molecules, ovalent compounds exist as simple molecules where the atoms are joined toget covalent bond, made up of a shared pair of el represented by a short straight ln Complete Table 3.03 by filling in the blank spaces. eee Formula Pn cnn hydrogen chloride water HO ammonia = f% cf cH, S ) c=8QS Table 3.03Chapter C3: Elements and compounds b Silicon(v) oxide is @ very common compound in the crust of the Earth. Ithas a giant covalent structure similar to diamond. Summarise th featur men of the structure of silicon(v) 0 (silica), as shown in the diagram, by completin he following stat + Thestrong bonds between the atoms are bonds. crystal, there are two oxygen atoms F every silicon atom, so the formulas, + The atoms of the lattice are organised in arrangement like diamond, with a silicon atom at the centre of each + This example of a structure, + Each oxygen atom forms, covalent bonds. + Eachsilicon atom forms, covalent bonds. € Graphite is one of the crystalline forms of carbon, wo of the distinctive properties of graphite ar + itconducts electricity even tf jough itis a non-metal, and + itcan act as lubricant even though it has a giant covalent structure Give a brief explanation of these properties in the light of the structure of graphite, i Graphite as an electrical conductor i Graphite asa lubricantCres Exercise C3.05 Formulae of ionic compounds The writing of chemical formulae is central to chemistry. This exercise will help you understand how to work out the formulae of ionic compounds and what such formulae mean. Table 3.04 shows the valencies and formulae of some common ions. erence ‘magnesium (Mg aluminium (cations) assium (K") copper (Cu iron (Fe silver (Ag) zinc (Zn? chromium (Cr CnC EeRe ammonium (NH,’) Poeorety chloride (CI oxide (0: (anions) bromide (Br sulfide (S iodide (1 EER nitrate (NO,) carbonate (CO. hydroxide (OH sulfate (SO. Table 3.04 a Use the infor iv Silvernitrate v Magnesium bromide Ammonium sulfate Magnesium nitride Potassium phosphate ix Ironia) hydroxide X —Chromium\w) chloride Use the information in the table and your answers ina above to give the ratio ofthe different atoms in the following compound 1 Copper oxide cu:0 Magnesium bromide Mg:Br Magnesium nitride Mg:N Ww _lron(a) hydroxidh 2:0:H N:H:S:0emer s eee ur rea) € The diagram below shows a representation ofthe structure of an ionic oxide. i Whatis the ratio of k'ions toO ions? d_ Thefollowing diagram shows the structure of common salt i Extend the structur he right, by adding four more ions. sin the structure to show their electron arrangement. (> ~~ \N7Tare ace ke keer Cs Exert C3.06 The bonding in covalent molecules The representation of the structures of covalent molecules is another important feature of chemistry. This exercise helps you develop your understanding of such structures and how to draw dot-and-cross diagrams of the sharing of electrons in these compounds. Compl and d structural diagrams to represent the bonding in the following molecular s.In the dot-and-cross diagrams, show only the outer shells of the atoms involved. Molecule Dot-and-cross diagram pete ‘Ammonia (NH,) Water (H,0) Ethane (CH) Ethene (CH,) | [Ethanol (¢,H,0H) Table 3.05Chapter C3: Elements and compounds Exercise C3.07 The nature of ionic lattices This exercise will help you relate the structures of ionic compounds to some of their key properties. The diagram shows a model of the structure of sodium chloride and similar ionic crystals, Theions re arranged in a regular lattice structure — a giant ionic lattice. The boxes below contain properties of ionic compounds and their expla Property tions. Draw lines to link each pair Explanation The solution of an ionic compound in water is a good conductor of electricity ~ such ionic substances are electrolytes, The ionsin the giant ionic structure are always copper axide + carbon dioxide cea’ Stent ae ee copper oxide + hydrogen —> copper > water Cuols) + Hie) 9 Culs) + H,0%) ‘eduction methane + oxygen —> carbon dioxide + water CHig) + Ole) > COB) +24,0() combustion potassium iodide + chlorine —>potassium chloride + iodine 2ileq) «+ Chi) “> -2KCllaq) + aa) Uisplacement copper sulfate + zine —3 zinc sulfate + copper CuSO.aq)_ + Zn(s)—> ZnS0,(aq) + Culs) displacement.Exercise C4.01 Key chemical reactions This exercise is designed to support your understanding of the basic aspects of some important types of chemical reaction. ‘Complete the diagrams to show what substances sugar are used and what is produced in burning, respiration and rusting RESPIRATION [——r wate ge neat energy hydrocarbog carbon diode iron [suming -——> ongen———a]_RusTING. L-_-» aust b_ What type of chemical change is involved in all of the above reactions? © Oxids Complet 1 and reduction reactions are important, There are several definitions of oxidation and reduction. he following statements. + asubstance gains oxygen duringa reaction its oi + ifasubstance oxygen during a reaction, itis reduced. d_ The diagram shows A the oxidation of copper to copper oxide and B the reduction of copper oxide back to copper using hydrogen. copper powder hycogeni iyrogen burning {__Fillinthe boxes on the equation shown inthe diagram with the appropriate terms. What type of agent is hydrogen acting as in this hast reaction’... uo +H, + cu + H,0e Afurther defi links oxidation and reduction to the exchange of electrons during a reaction. i Complete the following statements. of electrons. + Reduction is the ofelectrons. ii Fillin the boxes on the ionic equation shown in the diag with the appropriate terms. +(aq) —» Zn2*(aq) + Culs) What type of agent are copper ions acting asin this reaction? Exercise C4.02 The action of heat on metal carbonates This exercise will help you recall one of the major types of chemical reaction and help develop your skill at deducing conclusions from practical work. a What type of reaction is this? b Name the gas produced during the breakdown of a metal carbonate, and describe a chemical test for this gas. © Astude ates the breakdown of five different metal carbonates using the apparatus shown in the following diagrammical She heats 2 0.010 mol sample of each carbonat the time it take using the blue flame of the same Bunsen burner. She measures 2s for 100 cm? of gas to be collected in the gas syringe. Table 4.01 shows her results. | metal carbonate [20 metal B carbonate [105 metalCcarbonate [320 1No gas produced after 1000 metal E carbonate _[60 - Table 4.01 Infact, the student used samples of calcium carbonate, sa MANS ot Heal copper(i) carbonate, magnesium carbonate, A sodium carbonate and zinc carbonate, B Given the information that the more reactive a metals, c the less easy itis to break down the metal carbonate, [> complete Table 4.02 to show the identity of each metal fe A.B.c,DandE l Table 4.02 Write the chemical equation for the breakdown of zinc carbonate, Exercise C4.03 The nature of electrolysis This exercise will help you summarise the major aspects of electrolysis and its applications. ‘a Complete the following passage by using the words listed below. anode electrodes current molten electrolyte solution positive hydrogen molecules. lose oxygen cathode Changes taking place during electrolysis During electroly -ompounds are decomposed by the passa; ic current. 9 this to happen, the compound must be either orn. Electrolysis can occur when an lectric passes through a IRs The two rods dipping into the electrolyte are called the. In this situation, metals are deposited at the. and non-metals are formed at the. When the ionic compounds dissolved in water, the electrolysis can b @leCtFOLYSIS ans aeseee ONS Move towards the... sean. and negative ions move towards the At the negative electrode (cathode) the metal or electrons and form metal atoms or hydro Passe [At the positive electrode (anode) certain non-metal ions, ectrons and ‘or chlorineis prodb Complete the passage by using the words listed below, hydrogen hydroxide lower copper sodium eryolite purifying positive concentrated molten Examples of electrolysis in industry There are several important industrial applications of electrolysis, the most important economically being the electrolysis of ‘aluminium oxide to produce aluminium. The aluminium oxide is mixed with olten to ue, the melting point of the electrolyte A ‘aqueous solution of sodium chloride contains, ‘chloride, hydrogen and ions. When this solution is electrolysed.... .wefather than sodium is discharged at the ‘negative electrode. The solution remaining is sodium hy a solution of copper sulfateis electrolysed using ‘electrodes, an unusual thing happens and the copper atoms of the. {electrode (anode) go into solution as copper ions. At the c ‘copper ions turn into copper atoms, and the metal is deposited on this electrode. This can be used as a met! fefining or impure copper. Exercise C4.04 Displacement reactions of the halogens This exercise skills in organi build your understanding of a certain type of reaction and help improve your 1g and presenting experimental observations. The halogens - chlorine, bromine and iodine -diferin terms oftheir ability to — isplace another halogen from a solution of its salt. The following are some SL NX tes from a students experiment, They include some rough observations e “ from the tests carried out The halogens were provided as solutions in water and the test was to add the halogen to the salt solution. Solutions of potassium chloride, potassium bromide and potassium iodide were provided (see diagram) To add further observations, hexane was also available as a solvent to mix with the reaction mixture at the end of the experiment. Ifthere appeared to ‘a reaction, the product was shaken with hexane and the layers allowed to separate. The colour, if any, of the hexane layer was noted.ical reactions Results Rough notes: 1. KCIsolution with bromine or iodine solutions hexane not added. urless 2. KBrsolution h iodine solution - n urless solution ~ hexane not added 3 KBrsolution, with chlorine solution - solution colourless hexane layer at end, 4 Kisolution with chlorine or bromine water - solution. rexane layer at end (brown colour of aqueous | a Take vations and draw up a table of the results. if there is write'no ri Use this checklist to give yourself a mark for your results table. For each point, award yourself: + 2marks if you did it really well + 1 mark if you made a good attempt at it, and partly succeeded + Omarks if you did not try to do it or did not succeed. Self-assessment checklist for results tables: Seen (een a acy You have drawn the table with a ruler. The headings are appro you expect to make. rate and cover the observations and The observations are recorded accurately, clea concisely - without over-elaboration. The table is easy for someone else to read and understand Total (out of 8) 8 Excellent 7 ¢ 5-6 — Agoodstart, but you need toimprove qui 3-4 Poor. Try this same resul e abit able again, using a new sheet of paper 1-2 Verypoor. Read through all the criteria again, and then try the same results table agairaE eC) th increasing reactiv Exercise C4.05 Self-heating cans, hand warmers and cool packs Chemical reactions involve energy changes and this fact can be exploited for a range of practical purposes. This exercise illustrates those purposes and introduces aspects of exothermic and endothermic reactions which will also be met in later chapters. Self-heating cans Drinks, soups and other foods can be purch: expeditions and in circumstances where ased in self-heating cans. Such containers are particularly useful on ‘ansportation space is restricted. These cans rely on a chemical reaction that produces sufficient heat to raise the temperature of the drink or food that surrounds the reaction vessel, The most common reaction used is the reaction between calcium oxide (sla lime) and water. When this reaction takes place, a great deal of heat is given off and the solid calcium oxide swells, py a greater volume. d The diagram shows one way in which such acan may be constructed. energy release calcium ‘oxide (Ca0) point of activation a What term is used for a reaction that gives out heat to the external surroundings?Chemical reacti b_ What problem might arise because of the expansion of the solid when wateris added? € Lookcarefully at the diagram and suggest how this problem might be overcome, 4d Write the word and balanced chemical equations for the reaction between calcium oxide and water @ Howis calcium oxide manufactured from limestone? £ Using the internet, find two other exothermic reactions that are used in sel-heat Heat pads and hand warmers ctions are not obviously exothermic but have uses in this context. For example, generates heat for several hours and is used in pocket hand warmers (see diagram) for expeditions to cold regions. itis also used in the heat pads employed in first a hes and pains caused by strain in muscles and joints. ting reaction of a The heat p contains iron powder and water absorbed within the pad. While sealed, the rusting reaction cannot take hat further reactant is needed which only comes into play when the sealed packaging is opened? b_ Rusts hydrated iron(u) oxide, Whatis the chemical formula of iron(u) oxide? Ky Instant Relief € Complete the equation for the formation of rust. Fe+ 1+ XH... Fe, 0,-¥H,0Ind warmers can be made using a solution of sodium thiosulfate which contains more than the normal amount of the salt that can be dissolved at room temperature. A metallic clicker’ is used to create a physical isturbance in the solution and the excess salt crystallises out, releasing a substantial amount of heat. i Whatis the term used for such a solution that contains more dissolved solute than is normal? i How can sucha hand warmer be re-used after the salt has been crystallised out? Isa hand warmer based on the rusting reaction re-usable? Explain your answer Cool packs Reactions that absorb heat from the surroundings are also of use inc cooled down or kept cool. There are two types of cool pacl imstances wher ings needed to be ate from the + Instant cool packs that contain a solid which dissolves endothermically in water that is kept s solid in the package until needed, nd which warms up: * Cool packs that contain a gel which is cooled down in a freezer (see diagram). This type of cool pack can be re-used. Nt PAR, mm instant cool packs usually contain crystals of ammonium nitrate together with a plastic bag of water » ctivate the pack. a Give another use for ammonium nitrate.b Giveone advantage and one disadvantage of this type of cool pack Advantage: Disadvantage \d other medicines cool in hot climates. Atemperature of 5°Cis ol packs can be used to keep vaccine usually required. Devise an experiment to discover how much ammonium nitrate and h have to be used to produce the temperature of 5°C needed to keep a vaccine cool in hot desert conditions, Exercise C4.06 The movement of ions ‘This exercise introduces the idea of the movement of ions in an electrical field and the basis of the terms ‘anion’ and ‘cation’. mp and a small the movement of fons. The filter paperis student set up an experiment lke this to look crystal of the solid being studied is placed in the centre as shown in the diagram. supply , ‘are shown in Table 4 Ered our moves ton purple positiv jum manganat | potassium sulfate, KjSO. white [no colours seen je, CuSO, blue blue colour move: wards negative copper su Table 4.03Renee) || @ Which of these ionsis yellow? | manganate copper potassium sulfate Explain why the purple colour moves towards the positive terminal in the potassium n nate experiment || € Listthe anions and cations involved inthis experiment, together with their formulae Anions d_ Suggest and explain what will happen ifthis experiment is repeated with a crystal of copper manganate(w) Exercise C4.07 Making and ‘breaking’ copper chloride The difference between synthesis and decomposition is emphasised in this exercise together with a consideration of the energy changes involved. ‘Dutch metal’ a form of brass containing a very high proportion of copper. It is generally used as very thin sheets for gilding, as imitation gold leaf synthesising copper(ii) chloride a What are the words we use to describe a metal that can be dra out and beaten into thin sheets? The following is @ description of the reaction of Dutch metal with chlorine gas to produce copper(i) chloride. orine gos us Aclea ina fume cupboard. The lid ofthe g tongs. dry gas jar is two thin sheets of Dutch metal are lowered int lid is quickly replaced. ne is observed and clouds of yellow ‘smoke’ are formed.Chapter C4: Chemical reactions Asmall volume of distile turquoise) solution is dwater is added to the gas jar and shaken to dissolve the smoke. A pole blue-green 1b What colouris chlorine gas is the reaction carried out in a fume cupboard? Is the reaction observ Quickly? Explain your answers, exothermic or endothermic? What feature of D ch metal helps the reaction take place @ What observation indicates that the solution obtained contains copper) chloride? Givethe chen ‘equation for the sy esis reaction that has taken place, & Dutch metals an alloy of copper (8496) and zinc (1694), What other salt may be present in the solution? Copperti) chloride diagram n be decomposed to its elements by electrolysis. simple cell such as the one shown in the Decomposing copper(t) chlorideon taking place during this electrolysis, sted at the anode to sho youtartthe gee 4 Amuch simpler set of apparatus can be used sis. Thisis shown in the diagram bel | i. fthis simpler apparatus is used, where must the electrolysis b i Using this simple apparatus, there is no coll gas produced. H. orine had been produced in this case? Explain why it would wor tion of ‘ould you test to‘@ Is the decomposition of copper(t) chloride exothermic or endothermic? What type of energy isinvolved in this reaction? Write the half-equations for the reactions taking place at the anode (positive electrode) and the cathode negative electrode). ‘At the anode: tthe cathode:Acids, bases and salts Qui EEE ‘acid: a substance that dissolves in water to give. solution with a pH below 7 base: a substance which will neutralise an acid to give a salt and water only alkalis a base that dissolvesin water PH scale: a measure ofthe acidity or alkalinity ofa solution (scale from 0 to 14) Indicator: a substance that changes colour depending on whether it isin an acid ar alkali ‘salts anionic substance produced from an acid by neutalisation with a base ‘neutralisation: reaction a reaction between an acid and a base to produce a salt and water only SS Neutralisation reactions ‘Other characteristic acid reactions Hellag) + NaOH(aq)—> NaCllag) +H,O) ‘€aCOJ6) + 2HC\iaq)—> CaC,(aq + CO, + 4,010 H,SO,(aq) + 2KOH(aq)—> K,SO,/aq)*2H,0() _CuCOJS) +H,50,faq)—> CuS0./aq) + COL) + H,0() ‘CuOIs)+H,50,(0q)—> CuS0,(09)+ H,010) 2a(3)+ H,$0,(aq) —> 2n50,(aq)+ He) Mais) +2HCl(aq) —> MeCl(aq) + Hyle) so Exercise C5.01 Acid and base reactions - neutralisation This exercise will help you familiarise yourself with some of the terms involved in talking about acids and bases. c he ist below tofillin he following stateme acid carbon dioxide hydrogen hydrated anhydrous metal sodium sulfuric waterreece eee ee Exercise C5.02 Types of salt This exercise aims to increase your confidence in predicting the products of the characteristic reactions of acids, particularly in terms of naming the salt produced in a reaction, Salts are produced in reactions where the hydrogen of an acid is replaced by metal ions or the ammonium ion salts. Sulfuric acid, for instance, always produces sulfates. Each acid gives a characteristic family of ‘a Complete the following statements for other acids. 1 Hydrochloric acid always produces, iii Ethanoic acid always produc b Complete Table 5.01 which summarises the products of various reactions of acids. eee Winer) dilute sulfuric acid copper sulfate water and carbon dioxide [magnesium sulfate | water and carbon dioxide magnesium chloride | hydrogen dilute hydrochloric acid | copper oxide fs | dilute ethanoic acid jiumethanoate | water Table 5.01Exercise C5.03 Antacids This exercise discusses the different compounds that we can use to counteract the effects of acid indigestion. The reactions involved with the different remedies are considered. The human stomach contains hydrochloric acid with a pH of about 2. This plays @ part in the pr digest our food. Acid indigestion (heartburn) is due to the stomach producing too much hydroc! causes discomfort and often pain, ‘One way to deal with this is to take an antacid. Antacids (shown in the diagram below) contain chemicals which react with and neutralise the acid in the stomach, Ong Below are listed a number of common ingredients of antacid remedies: + sodium carbonate + sodium hydrogencarbonate + calcium carbonate + magnesium carbonate + magnesium hydroxide + sodium alginate, a Write equations showing the react hydrochloric acid ons between magnesium c and magnesium hydroxide with i Mec fi Mg(OH b_ Why might the reaction with magnesium carb re cause some discomfort?ems Cor ae © Some of the compounds listed earlier are soluble in water, i Which two compounds are soluble in water? i Why might these compounds work more quickly Sodium alginate does not neutralise acid, Use the internet to find why itis used in antacids, Exercise C5.04 Fire extinguishers Carbon dioxideis often used in fire extinguishers. This exercise describes a traditional ‘wet” carbon dioxide extinguisher, and discusses the different types of extinguisher and their appropriate use. You can use the internet to research other types of fire extinguisher. The diagram shows an early type of fire extinguisher. The extinguisher was turned upside down, causing the stopper to come out of the acid bot The reaction between acid and carbonate then produced a mixture of water and arbon dioxide which was squirted at the fire. It was important that a large volume of carbon dioxide was produced quickly. This type of extinguisher is not suitable for all types offre. Itis possible to use sodium hydrogencarbonate instead of sodium carbonate and tead of sulfuric acd, ydrochloric a ‘Below are the equations for the possible reactions: 1 NajCO, + H,S0,—> Na,S0,+H,0 +0, 2. Na,CO,+2HCI—>2NaCI + H,0+c0, 3. 2NaHCO,+ H,S0,—>Na,SO, +2H,0+ 200, 4 NaHCO, +HCI—> NaCl + H,0+.0, al volumes, ‘Answer the following questions, assuming that all four solutions are ofthe same concentration and ine 1. Which combination(s) would produce carbon dioxide most quickly? Explain your answerii Which combination(s) would produce carbon dioxide? Explain b_ Use the internet to discover what types of fre extinguisher are used now. Comment on the type(s) of ey are useful for and the types they are not. € Which extinguisher is sometimes called the ‘universal extinguisher’ and why? Exercise C5.05 Descaling a coffee machine The formation of limescale in coffee makers, kettles and hot water pipes is a problem in certain areas. This exercise considers various acids that are used to remove limescale and their effectiveness.ame Eee ec Coffee makers (see diagram, previous page) can become blacked with limescale’ in hard water areas, Limescale is calcium carbonate which precipitates from the hot water in the machine and blocks the pipes. is often necessary to ‘descale’ the machines, Thisis done by passing acid through the pipes. The acid reacts with the calcium carbonate and so removes it. The following acids have been used for descaling: + hydrochloric acid + cittic acid + ethanoic acid (vinegar + sulfamic aca, ‘a Write word and symbol equations for the reaction between calcium carbonate and hydrochloric acid. b_ What name would be given to th salt formed when citric acid reacts ‘© Why might these acids not be the best to use for descaling a coffee machine? Wy migt i Hydrochloric acid Wi Ethanoic ac h the internet to find the a swers to the following questions. 1 What isthe formula of sulfamic acid and whatisit used for? Hl Why does water sometir produce calcium carbonate (limescale) when itis heated? What is hard water?Dea EUR aT Exer e C5.06 The analysis of titration results This exercise will develop your understanding of some of the practical skills involved in acid-base titrations and the processing and evaluation of experimental results. A student investigated an aqueous solution of sodium hydroxide and its reaction with hydrochloric acid, He carried out two experiments. Experiment 1 i @ measuring cylinder, 10 cm? ofthe sodium hydroxide solution was placed in a conical E $k. Methyl orange indicator was added to the flask Aburette was filled to the 00 cm! mark with E hydrochloric acid (olution P E he student added solution P slowly tothe alkal inthe flask until the colour just chang E Use the burette diagram to record the volume in the results table and complete the c Experiment 1 in Table 5.02. fre Experiment 2 Experiment 1 was repeated using a different solutior loric acid (solution Q). E to record the volumes and complete the Experiment 2 = E na 16 Ear final reading nitial reading 00 difference | Table 5.02 What type of chemical reaction occurs when hydrochloric acid reacts with sodium hydroxide? Write a word equation for the reaction. € What was the colour change of the indicator observed? d_ Which of the experiments used the greater volume of hydrochloric acid?@ Compare the volumes of acid used in Experiments 1 and 2 and suggest an explanation for the difference between the volumes, £ Predict the volume of hydrochloric acid P that would be needed to react completely if Experiment 1 was repeated with 25 m* of sodium hydroxide solution, Volume of solution needed: Explanation & Suggest one change the student could make to the apparatus used in order to obtain mor Exercise 5.07 Thermochemistry - investigating the neutralisation of an acid by an alkali This exercise introduces an unfamiliar form of titration and further develops your skill presenting, processing and evaluating the results of practical work. The reaction between dilute nitric acid and dilute sodium hydroxide solutions can be investigated by thermochemistry. This can be done by following the changes in temperature as one solution is added to another. Apparatus + poystyrene cup and beaker + 25cm!measuring cylinder + 100m? measuring cylinder + thermometer (to 100°) safety glasses -to be used when handling the acid and alkali solutions Method ‘An experiment was carried out to measure the temperature changes during the neutralisation of sodium solution with dilute nitric acid. Both solutions were allowed to stand in the laboratory for about 30 min. ddroxide 25 cm’ of sodium hydroxide solution was added to a polystyrene beaker and the temperature was measured. Then 10 cm’ of nitric acid was added to the alkall in the beaker and the highest temperature reached was measured. he experiment was repeated using the f wing volumes of acid: 20, 30,40, 1nd 69cmCambri Results Temperature of alkali solution at start of experiment =21.0°C The following were obtained for the different volumes of added acid use and 275 "C respectively table Use this checklist to give yourself a mark for your results table. For each point, award yourself: + 2mark you did it really welt + Amarkif you made a good attempt at it, and partly succeeded + Omarks if you did not try to do it, or did not succeed. Self-assessment checklist for results tables: Check point (eee You fetes You have drawn the tablé with a ruler The headin, re appropriate and have the fect units in able is easy for someone else to read and understand. | Ifthe table contains readings, all are to the same number | ofdecimal places 5,14.2,etc [Total (out of 8) 8 lent 7 5-6 but you need to improve quite abit 34 this same results table again, using a new s per 1-2 Very poor. Read through al the citer again, and then try the same results table ag1b Plota graph of the temperature of the solution against the volume of acid added to the alkal © Drawsuitable ines through the points on your graph. (Note tha re two parts to this graph so you will .ed to draw two straight lines through the points and extend them until they cross) tobe inaccurate? @ From these resi work out the volume of acid needed to neutralise 25. plain why you have chosen this value. ide solution m? of the sodium hyd!rer Ste Ey Use the checklist below to give yourself a mark for your graph. For each point, award yourself: + 2marks if you did it really well + Lmarkif you made a good attempt ati, and partly succeeded + Omarks if you did not try to do it, or did not succeed, Self-assessment checklist for graphs: Check point een u have drawn the axes with a rul width and height of the grid You have used a good scale for the x-axis and the y-avis, going up in 1s,25,5sor 10s. You have labelled the axes correctly, giving the correct. Units for the scales on both axes. using most of the You have plotted each point precisely and correctly You have used a small, neat cross for each point. You have drawn a sing set of points - using a ruler for straight lines - and have extend ie, clear bestit ine through each the lines to meet. any anomalous results when drawing the Total (out of 14) 12-14 Excell 10-11 Good 7-9 Agood start, but you need to improve quite abit 5-6 or. Try this same graph again, using anew sheet of graph paper. 3-4 Very poor. Read through all the criteria again, and then try the same graph again, Whywere the solutions left to stand for about 30 min bet he experiments? & Why was a polystyrene beaker used instead of a glass beaker? Jggest three improvements that would make the experimernest 1 Write the word equation and balanced chemical equation for the reaction, J. Isthereaction exothermic or endothermic? k. Theconce, of this s tration of the sodium hydroxide solution is 1.0 mol/dm*. How many moles are there in 25 cm’ ution? (Remember there are 1000.cm*in 1 dm?) 1 Look at the equation and work out how many moles of nitric acid this would react with 'm Calculate how many moles of acid there are in 1000 cm? of the acid solution, What is the concentration of th acid solution in mol/dm??Quantitative chemistry (Qe ‘relative atomic mass: the average mass of naturally occuring atoms of an element on a scale where the carbon-12 atom has @ mass of exactly 12 units ‘relative formula mass: the sum of all the relative atomic masses of al the atoms or ions in @ ‘compound 4 4 TREE ‘moles the relative formula mass ofa substance in grams ‘molar gas volume: the volume occupied by 1 mole of any gas (24 dm at room temperature and pressure) Exercise C6.01 Calculating formula masses This exercise will develop your understanding and recall of the ideas about atomic and formula mass. mplete the following diagb Complete Table 6.01 of formula masses for a range o (O=16,H=1,C=12,N=14,Ca=40, Mg=24) jifferent types of substance. (Relative atomic masses conygen 20 2*16=32 carbon dioxide 1Cand20 _|pa2+2%16 _ H,0 2Hand1. = LNand 3H = MgO 1*24+1%16 | | ammonium nitrate | NH.NO. ANHi and. 2x14+ ‘ 80 | propanc GH,OH 36, and 3x12+8x1+ 7 Exercise C6.02 A sense of proportion in chemistry This exercise will familiarise you with some of the basic calculations involved in chemistry. produce 4 tonnes o its oxide. In the ed f ustrial extraction prc zinc. Calculate the mass of zinc, in tonnes, that isp iced from 2 1b Nitrogen and hydrogen react together to form ammonia N,+3H,—> 2N When the reaction is complete, 14t nitrogen 1es of nitrogen are converted into 17 tonnes of ammonia, How much 4 tonnes of ammonia? be needed to produce © Thesugar lactose, C,:H,,0,,. is sometimes used in place of charcoal in firew State the total number of atoms present in a molecule of lactosed_ Amolecule of compound ¥ contains the following atoms bonded covalently t + twoatoms of carbon (C) + two ators of oxygen (0) + fouratoms of hydrogen (H) What is the formula of a molecule of ¥? Exercise C6.03 Calculations involving solutions This exercise will help develop your understanding of the idea of the mole and its application to the concentration of solutions. It will develop your skills in processing practical data from titrations. Testing the purity of citric acid acid is an organic acid which is a white solid at room temperature. It dissolves readily in water. ity of a sample of the acid was tested by the following method. issolved in 50 cm? of distilled water, of0.48 g citric acid was ‘of thymolphthalein indicator were added (colour change is from col blue in alkal + Step 3: The solution was then titrated with a solution of sodium hydroxide (0.50 mol/dm?) inthe diagram below and give the colour of the nplete the labels for the piece: olution before titration. of apparatus shot rt \ [505 ] fom ation. Complete the table by filing in the Final burette rea First burette r Pome eer ere eas Table 6.02eee eee uta Calculate the purity ofthe citric acid by following the stages outlined here. Stage 1: Calculate the number of moles of alkali solution reacted in the titration, + Pcm*of NaOHiaq) containing 0.50 moles in 1000 cm? were used. 0.50 1000 + Number of moles NaOH used HP EQS assssssntnsnnrnes OURS, ‘Stage 2: Calculate the number of moles of citric acid in sample. + Note that 1 mole of c acid reacts with 3 moles of sodium hydroxide. + Then number of moles of citric acid in sample moles, Stage 3: Calculate the mass of citric acid in the sample and therefore the percentage purity. + Relative formula mass of citric acid (M, of C,H,0; )= (C=12;H=1;0=16) + Mass of citric acid in sample= Rx M,= S= 7 & » tsample=—5 5 + Percentage purity of sample=——— a ® aay) ¢ How-could the sample of citric acid be purified further Exercise C6.04 Finding the mass of 5 cm of magnesium ribbon This exercise will develop your skills in handling experimental data in novel situations. From the chemical equation for the reaction and using the relative formula masses together with the molar volume of a gasitis possible to predict the amounts of magnesium sulfate and hydrogei ‘magnesium are reacted with excess sulfuric acid, n that are produced when 24 gof This relationship between the mass of magnesium used and the volume of gas produced can be used to find the mass of a short piece of magnesium ribbon indirectly Apparatus and method A \ NX | “] J The experimental instructions were as follows, Wear safety goggles for eye protection. ‘+ Setup the apparatus as shown in the diagram with 25 cm of sulfuric acid in theener tetra: ne flask stopper as show -asure § cm of magnesium ribbon and grip it below per up tore the rib on and immediately replace it, © further bubbles rise into the measuring cylinder, record the volume of gas collec + Repeat the experiment twice more using 5 cm of magnesium ribbon and fresh sulfuric acid e +f average volume of hydrogen produced, Data handling Astudent tained the results shown in Table 6,03 when measuring the volume of hydrogen produced. Sie average Table 6.03 a Fillin the average jot the same? the results of Wu think possible You know that 24 g of magnesium will produ: needed to produce your volume of hydrogen? m of hydrogen. What mass. magnesium would b This isthe mass of § cm of magnesium ribbon. The weight is too low to weigh easily on a balance bu weigh a longer length and use that to check your answer. at mass of magnesium sulfate would you expect 5 cm of m esium ribbon to produce? ur predictior d_ Planan experiment to check whether yo! is correctfaryacy Peers Exercise C6.05 Reacting volumes of gases There is a direct relationship between the volume of a gas and the number of moles present in the sample, This exercise gives you an example of how to use that relationship for a particular experiment. Experiments show that volumes of gases react together in a ratio that can be predicted from the chemical equation for the reaction. FI singe Fq of nitrogen monoxide olongen Under the conditions as shown in the diagram, nitrogen monoxide (NO) reacts wi thatis 4 brown gas. In an experiment, 5.0 cm’ portions of oxygen were pushed f ‘oxygen (0) to form one product syringe Binto syringe A. Aiter each addition, the tap was closed, the gases were cooled, and then the total volume of ured. The results are shown in the graph. “ Gi o ining was * 0 5 4 a a er) Volume of onygen added /em? a Whatis the total volume of gases when feaction is complete? b What volume of oxygen reacts with $0 cm! of nitrogen monoxide?s the volume of the brown gas formed? d_Complete the following to work out the formula of the brown g NO + ©, > Exercise C6.06 Calculation triangles The conversion of the mass of a sample into moles and vice versa is central to chemical calculations because it gives us a measure of the number of atoms and/or molecules involved in reactions. This exercise will help you become familiar with the use of the calculation ‘triangles’ that are a memory aid to these conversions. moles, and moles to masse in the calculation triangle in the diagram below for changing between masses and moles. Then comy Table 6.04, (Use the following, values: H= 1, C= 12,N= M4, O= 16, Mg=24, $= 32, Cl=35.5,Ca=40,Cu Bieenenoa it [cu 128 | [me 05 SO, 25 ct 04 5 THO. 2 Table 6.04a eam eMC ee eI sy b Calculations involving solutions Fillin the calculation triangle in the diagram below for relating moles of solute to volume and concentration, Then complete Table 6.05 below. Se sodium 1dm' 0s chloride hydrochloric 500m: 05 acid sodium 2dm | hydroxide sulfuric acid 250.¢m' a | sodium 2 | thiosulfate copperti) OL 075 sulfate Table 6.05 Exercise C6.07 Scaling up! One aspect of carrying out calculations in chemistry is the scaling up of the amounts used to industrial proportions. This exercise gives you some practice at this skill, Inthe laboratory we are used to working with grams of material and our basis. However, an indu tonnes of produc ations are usually framed on that al chemist is often used to working on a significant larger scale and looking to produce 2. Inthis context, itis useful to know that the ri can be readily scaled up to p ting proportions determined by the equation forthe ovide useful data at an industrial level i What mass of ron(i) oxide is needed to produce 100g of ron, in the blast furnace below using your calculated figures. (Use the following, values: C= 12; 0= 16;Fe 1 equation for the reaction is: O(g) > 2Fe(s) +3C0,()ee) moles of Fe, so eMmoles of Fe,0, are needed for the re or gof xide. ji Using your calculated value for how much iron(i) oxide (hematite) is needed to produce ww much hem: eis needed to produce 50 tonnes of iron. scale industrial process is the production of quicklime from limestone by heating in a lime ki i Whatis the equation for the thermal decomposition of limestone? HW Usingy ime: ‘equation, calculate how many tonnes of quicklime would be produced from 1 tonne of one. (A, of Ca=40,aCe) mr-lem nel aceite PeRjparrescer ern sonar ST REET aa ‘exothermic reaction: 3 reaction that gives out heat tothe surroundings endothermic reaction: 3 reaction that takes in heat from the surroundings rate of reaction: the rate of formation ofthe products of a chemical reaction (or the rate at which the. reactants are used up) ceatatyst: 3 substance that speeds up a chemical reaction but remains unchanged at the end ofthe reaction enzyme: a protein that functions asa biological catalyst ‘activation energy: the minimury amount of energy the reacting molecules must have fora reaction to take place 'USEFUL REACTIONS AND THEIR EQUATIONS “These reactions are fen used to study reaction ates or are useful examples of reversible reactions: Mg + 2HC|—> MgCl, +H, CaCO, + 2HCI—> CaCl, + H,0 + CO, CuSO, + SH,0 *=* CuSO, 5H,0 21,042,010 048) Na,5,0,09) + 2HCIfaq) > 2NaC\aq) + $048) +},010 +S) J 2 | No 3H 20H, 2S0,(g) + 0,(g) = 2S0,(g)bridge IGCSE Comb Exercise C7.01 Terms of reaction This exercise should help you familiarise yourself with certain key terms relating to the progress of chemical reactions. nes to match the terms on the left with the correct statement on the right. Term Statement a substance that speeds up a chemical reaction exothermic reaction the industrial process for making ammonia a reaction in which the products may react to reversible reaction Berne produce the original reactay 2 reaction in which heat energy is given out to Haber process the surroundings Contact process the industrial process for making sulfuric acid Exercise C7.02 Energy diagrams This exercise is aimed at helping you understand energy level diagrams and their usefulness in showing why some reactions are exothermic while others are endother The energy changes involved in chemical reactions can be represented we reactants and products. ually by energy level diagram: he more stal Such diagrams show the relative stability of products, the lower their energy level|| The energy level diagram for an exothermic reaction is different from that for an endothermic reaction. || The following keywords/hrases will be needed tofiln the information boxes accompanying the diagrams. || given out positive taken in reactants negative products | | a exothermic reactions | > [recans > wi z progress of reaction se information from the diagram and the keywords/phrases to complete the following ormation box. in an exothermic reaction, the have more energy t the. This means that AW/is, The difference in energy is. as heat ii smperature of the surroundings increases / decreases. Endothermic reactions Products ropa ofan Again, use information from the diagram and the keywords/phrases to complete the following information box. endothermic reaction, the, have more energy than the. This means that AH is, he difference in energy is, from the surroundings. he ter erature of the surroundings increases / decreases. (Delete the incorrect word)kee Exercise C7.03 The collision theory of reaction rates This exercise should help you develop an understanding of the collision (particle) theory of reactions and how changing conditions affect the rate of various types of reaction. enter ce fee concentration all reactions involving sol or reactions involving gases lutions d already. The finist Complete the Table 7.01 from your understanding of the factors t the sections have been complet Brennan an increase in the concentration of or both, of t fect the speed (rate) ofa reactio cd table should then be a useful revision aid. increases the rate of react ne, or the pa more frequently means there | are more particles in the same volume pressure reactions involving | an increase in the pressure | greatly only therateot | reaction - the effectis the same as that of an increase in temperature | all reactions an increase in temperature this means that molecules the rate of reaction are moving and coll | more the using a catalyst particles also have when they collide more reactions involving solids and liquids, solids and gases or res of solids use the same mass of a solid | greatly increases the rate of but make the piece esof solid | reaction slow reactions can be speeded up by adding a suitable catalyst amount of required for the reaction to take theca of the reaction lyst is present in th atthe end the rate of reaction e place: | | Table 7.01Exercise C7.04 The influence of surface area on the rate of reaction This exercise should help develop your skills in presenting and manipulating experimental data. You will also be asked to interpret data and draw conclusions from it. ‘Auseful experiment that shows the effect of varying the surface area ofa solid on reaction rate is based on the fact that hydrochloric acid reacts with calcium carbonate to produce the gas carbon dioxide. The experiment was set up as shown in the diagram below using identical masses of marble chips. Flask Acontains larger pieces of marble chips and Flask B contains smaller pieces, The same concentration and volume of acid was used in both flasks ask Flake. cotton wool otton weal spr aah hydrochloric acid balance B he flasks were quickly and simultaneously set to zero on the balances. The mass loss of the flasks was then recorded over time, irite the word equation for the reaction between marble chips (calcium carbonate hydrochloric acid ) and dilute 1b What causes the loss in mass from the flasks? Readings on the digital balance were taken every 30 s, The balance had been tared (set) to zero at the startof the reaction, For the large pieces of marble chips (Flask), readings (in g) were: 0.00 | -0.21 | -0.46 | -065 -0ai | -091 092 | -0.96 | -o98 | -0.98 0.99 | -0.99 For the small pieces of marble chips (Flask B), readings (in g) were: (0.00 | 051 | -0.78 -091 | -094 | -0.96 98 | -099 [ -099 =1.00 | -099 | -1.00€ Create asuitable table showing how the mass of carbon dioxide produced (equal with time for the two experiments, Plot the two graphs on the grid. the faster rate of reaction? Explain why. {Explain why for both flasks, the same amount of gas is produced in the end.Sean Use the checklist below to give yourself a mark for your graph. For each point, award yourself: + 2marksif you did it really well ‘+ 1markif you made a good attempt atit, and partly succeeded + Omarks if you did not try to do it, or did not succeed. Self-assessment checklist for graphs: Check point eee You ioracerid You have drawn the axes with a ruler, using most of the width and height of the grid. You have used a good scale for the x-axis and the y-axis, going up in0.255,0.5s, Lsor2s. | You have labelled the axes correctly, giving the correct units for the scales on both axes. You have plotted each point precisely and correctly. You have used a small, neat cross or dat for each point. You have drawn a single, clear best-fit line through each set of points. You have ignored any anomalous results when drawing the ine through each set of points. Total (out of 14) 12-14 Excellent 10-11 Good. 7-8 Agood start, but you need to improve quite a bit. 5-6 Poor. Try this same graph again, using a new sheet of graph paper. 1-4 Very poor. Read through all the criteria again, and then try the same graph again, Exercise C7.05 Fin producing a gas g the rate of a reaction This exercise is based on an important practical technique of gas collection using a gas syringe. Following through the exercise should help develop your skills in presenting experimental data and calculating results from it. You will also be asked how the experiment could be modified to provide further data. Hydrogen peroxide, H,0,, is an unstable compound that decomposes siowly at room temperature to form water and oxyger 2H,0,(aq) > 2H, 01) + 0g)Da en Recent a) student investigated how the rate of decomposition depends on the catalyst. She wo catalysts manganese() oxide (Experiment 1) and copper (Experiment 2) The volume of oxygen produced by the reacti asured at different times using i sms below to complete the results for Ex yeriment 2in Table a Use the data from the d SITs 0 Lx 0 T ~T JL Time / min 1 2 3 | 4 5 6 9 7 23 3 35 mee) Petre cate 50 Bree yea) Table 7.02 'b Plot the results from Experiments 1 and 2.on the grid and draw a smooth curve through each set of point Label the curves you draw 1s exp. Land exp. 2Cee ALE ich of thetw /o experiments was the first to reach completion? Explain your answer d__Use your graph to estimate the time taken in Experiment 3 to double t 15.cm? to 30 cm?, Record your answers in Table 7.03, and indicate on the, obtained your values. eke ce n ead Sree kere Cat Time taken to double the volume from 15 cm? to 30 cm? / min Table 7.03 Experiment 2 (using manganese(iv) oxide) (or speed) of a reaction may be calculated using the formula: volume of oxygen produced / em’ ime taken /min Using the two graphs and the al each experiment. ve formula, calculate the rate of each reaction after the first 2.5 min fo f Fromyourar wer toe, suggest plain your answer. which isthe ter catalyst, manganese(v) oxide or copper. g Atthe end of Experiment 2 the copper was removed How would you predict this mass of copper would r was dried and weighed. mpare with the mass of copper added at the start of the experiment? Explain your answefe ca gest how the rate: ‘decomposition in either experiment could be furtherincreased Exercise C7.06 Runaway reactions This exercise is designed to introduce the idea of ‘runaway reactions’ and to develop your data handling and interpretation skills. tion which becomes uncontrollab ermic, During an exothermic reactio increases the rate of rea ‘Acommon example is a reaction whic exot n, the reaction mixture increases in temperature, and this furth« ion. Heat is then produced more rapidly and the rate increases further. In an industrial ‘explosion and great danger to people li process, thiscan cau tiga ling very exothermic on using the investigati ions, nent, he took 10.¢m*o sulfuric acid, noted its tem ature and then added 0.1 g of magnesium ribbon, He measured the volume of gas produced in the first 30 sof the reaction and noted the temperature when F the reaction stopped. To make the react a fair test, he kept the amounts of magnesium and sul but he changed the conditions by adding a different volume of wate ric acid the same in each experiment, (0 the acid in each case before adding th The student's results are shown in Table 7.04 rar Seen? Final eee tcei ae et aL Care Cer) Poecer ny Bee nears ia Eee 40 02 0 2 25 4 Table 7.04 lete Table 7.04 by filing in the second and fith columns.Prats) Plot graphs of the data on the grid provided. 15 3 10 0 + { 5 ° 0 to os a7 06 05 04 03 2 0, Concentration of acid mol? € Unusually, the horizontal (x) axis has been shown with a decreasing scale of concentration values, i i ifconcentration is decreasing, what property ofthe solution is increasing i Whateffectis plotting the graphs in this way designed to emphasise? d_ Whyccan you be sure that the amount of energy produced in each reaction is the same? he temperature change different in each case? Nhat do the volumes of gas collected tell you about the rate of the different reactions?& Inindustry three things are important ty of the tory, the workers and the environm how much product is made (the more the better} how quickly the product sduced (the more quickly the better Bearing Id you give a fa magnesium and sulfuric acid on a large scale? in mind, what adv jory that was going to use ti Use the checklist below to give yourself a mark for your graph. For each point, award yourself: + 2marks if you did it really well + Lmark if you made a good attempt at it, and partly succeeded + Omarks if you did not try to do it, or did not succeed. Self-assessment checklist for graphs: Marks ic mary t precisely and correctly for i different scales on the two horizontal axes, You have used a small, neat cross or dot for one graph points of You have used a small, but different, symbol for the poin ofthe other graph, You have drawn a best-fit line through one set of points, You have di poi ‘a best fit line through the other set of ts using a different colour or broken line. You have ignored any anomalous results when drawing the Total (out of 12) 10-12 Excellen 1-9 Good 4-6 good start, bu 1u need to improve quite a bit 2-3 Poor. Try this same graph again, using a new Sheet of graph paper 1 Very poor. Read through all the criteria again, and then try the same graph again,Patterns and properties of metals Qe ‘alkali metal: a reactive metal in Group | of the Periodic Table; alkali metals react with water to produce alkaline solutions transition metal: 2 metal in the central block of the Periodic Table; transition metas are hard, dense ‘metals thatform coloured compounds and can have more than one valency ‘reactivity series a listing ofthe metals in order oftheir reactivity USEFUL REACTIONS AND THEIR EQUATIONS. 2Na + 2H,0—>2NaQH +H, Fe,0, + 21> Al,0, + 2Fe Zn(s)+CuS0,(aq)—92NS0.{a9) +Culs) Exercise C8.01 Group I: The alkali metals This exercise should help you learn certain key properties of the alkali metals, and help develop the skills of predicting the properties of unfamiliar elements from the features of those that you have learnt. a State two physical properties of caesium b State the numberof elplete Table 8.01 to estimate the boiling mic radius of caesium. Comment also on the reactivity of potassium and caesium with water, sodium 0.191 883 floats and fizzes quickly on the surface, disappears gradu does not burst into flame J potassium] 0.86 0235 760 rubidium | 153 0.250 686 reacts instantaneously, fizzes and bursts into flame, then spits violently 7 and may explode caesium 1.88 Table 8.01 d_ Write the word equation for the Exercise C8.02 The reactivity series of metals This exercise should help you familiarise yourself with certain aspects of the reactivity series. Itshould also help develop your skills in interpreting practical observations and predicting the properties of unfamiliar elements from the features of those that you have learnt. Using the results of various different types of chemical reaction, the metals can be arranged into the reactivity se ‘a Magnesium reacts very slowly indeed with c nagnesium oxide and a gas. Wri ter but it does react strongly with steam to give 1e word equation for the reaction between magnesium and ose one metal from the reactivity series that will not react with steam.ged eee an akc ¢ Choose one metal from the ctivity series that will safely react with dilute sulfuric acid d _Ineach of the experiments below, a piece of metal is placed in a solution of a metal salt. Complete Table 8.02 of | observations } tee A ihe copper copper oper iver ile sulate sulfate sul iat solution elution solution solution lt | colour of FEM lsilver-coloured |silver-coloured | Cal Petree pale green lbtue blue Jcolourless Peta At colour of ae coated with |silver-coloured [coated with Cee 2 <%2ll brown solid silver-coloured crystals crystals PME colourless palegreen —_[olue Potten) Tebleso2 go Use these results to place the metals copper, iron, silver, zinc in order of reactivity (putting the most reactive metal first The reactivity ser of metals giv in Table 8.03 contains both familiar and unfamiliar | elements. The unfamiliar elements are marked with an asterisk). Choose metal(s)from | DU" this ist to answer the following questions. thanum* | aluminium f Which two metals would not react with dilute hydrochloric acid? vine chromium* iron || & which two unfamiliar metals would react copper palladium* with cold water Table 8.03 | Name an unfamiliar metal th | witharbon, uld not be extracted from its oxide by reductionTEC Ra Exercise C8.03 Energy from displacement reactions This exercise will help you practise the presentation and interpretation of practical experiments, When a metal is added to a solution of the salt of a less reactive metal, a displacement reaction takes place, |, The equations for two different examples are: | Fe(s) + CuSO,(aq) > Cu(s) + FeSO (aq) zine + copper sulfate—> copper + zinc sulfate ‘The energy change involved in these reactions can be measured by adding 5 g of metal powder t (0.5 mol/dm: copper) sulfate solution in a polystyrene cup. The temperature the metal. The powder is then added, the reaction mixtures stirred continu every 30s for3 min, ‘cm? of olution is taken before adding sly, and temperatures A student took the readings that follow when carrying out this experiment. fend oo [05 | 10 [| 1s [ 20 [ 25 | 30 Sree ecne nae tras a | |e [a [7s | 2 Seeley a[oslea2}si[a|s|« Table 8.03 ‘a Plottwo graphs on the grid provided and label each with the name of the metal. 1b Write the word equation for the first reaction and the balanced symbol equation for the second,c ron or zinc, produced the larger temperature rise? this metal gave the larger temperature rise, | © Comment on whether this experimentis a ‘air test Explain your answer. Use the checklist below to give yourself a mark for your graph. For each point, award yourself: Self-assessment checklist for graphs: Check point (eee cher You have drawn the axes with 2 ruler, using most of the width and height of the grid You have used a good scale for the x-axis and the y-axis, ing up in useful proportions. | You have labelled the axes ¢ for the scales on bot! rectly giving the correct units axes. You have plotted each point precis ely and c u have u ‘a small, neat dot or cross for each point. You have drawn a single, clear bestit ine through each s ofpoints usin aruler fora straight line. You have ignored any anomalous results when drawing the lines through each set of results Total (out of 14) 12-14 Excellent 10-11 Good. 7-9 — Agood start, b 5-6 Poo utyou need to improve quite a bit. ry this same graph again, using @ new sheet of graph paper. 1-4 Very poor. Read through all the criteria again, and then try the same graph again,mbined a Exercise C8.04 Metals and alloys This exercise discusses some aspects of alloys and their usefulness. It explores the advantages and specific purpose of certain alloys. a = 2nd [low [high [high 1535 10 Btaniom [wth [veryfigh [low [high 1660 02 aluminiu Ist high low medium 660 | 35 zine wath [low [high [low copper 2oth iow [high [mediums | 088 60 tn “oth [low [high [2 08 iced | 30th [low | veryhigh a 05 Table 8.04 104 to answer the following ques a Why is aluminium used for overhead power cables? Why dothe aluminium cables have an iron (or steel) core? is copper used instead of aluminium in wiring in the hom d_ Why istitanium a good metal to use for et ai mula 1 racing cars are usually harder and stronger with ave diferent ey are made from, They elting s on circuit boards is a mixture of tin and lead @ Solder, which is melted to join together electrical componen Suggest why its used in preference to the pure metals.Chapter Brassis an alloy of copper and zinc. Itis used to make brass musical instruments and to make electrical connectors and plugs. There are two main types of brass: 60 40 and 70: 30 copper to zinc. The larger the amount of zinc, the harder and stronger the alloys. Suggest which alloy is used 2ach of the purposes mentioned above, Give @ reason for your answers. cu60: Zn40Industrial inorganic chemistry ‘chemical plant: the reaction vessels and equipment for manufacturing chemicals feedstock: starting materials for chemical industrial processes brine: a concentrated solution of sodium chloride ‘Haber process: the industrial process forthe: Toei 1 Contact process: the industrial process for the manulacture of sulfuric acid \ USEFUL REACTIONS AND THEIR EQUATIONS. Fe,0,+3CO—>2Fe + 360, blast furnace reaction 2C0,->C20+C0, lime kiln reaction AP() +36 Al) ‘extraction of aluminium | Ni@sshigezniis | Amepmees 20,8) +0,(g) 250g) Contact process Exercise C9.01 Metal alloys and their uses This exercise should help you recall details of different alloys and the basis of their usefulness. mplete Table 9.01 about the composition and usefulness of som Coy mild lour, harder than coppe bronze copper: 95 statues, church bells hard, does not pper: 1.2 Table 9.01Er easy Exercise C9.02 Extracting aluminium by electroly: This exercise should help you recall and understand the details of the method for extracting alumi Because of ts high reactivity, aluminium must be extracted by electrolysis. The electrolyte is aluminium oxide dissolved in molten cryolite. Hydrated aluminium oxide is heated to produce the pure aluminium oxide used. ALOy3HO > —AL,O,+3H,0 hydeated aluminium oxide a What type of reaction is this? Puta ring around the correct answer. decomposition ion oxidation b Whymust the electrolyte be molten for electrolysis to occu? © Whatis the purpose of the cryolite? d The following diagram shows an electrolysis cell. Which letter (A, B, Cor D) represents the cathode? g electrolyte aluminium ide dissolved in molten State the name of the products formed at the anode and cathode during this electrolysis. At the anode: At the cathode: Why do the anodes have to be renewed periodically? & Complete the equation for the formation of aluminium from aluminium ions, Ab + eA fh State one use of aluminiumExercise C9.03 The importance of nitrogen The following exercise connects the ideas surrounding the importance of nitrogen to agriculture and develops your understanding of chemical equilibria. It also develops your skills in processing and interpreting experimental results. Although certain bacteria in the soll convert nitrogen gas into nitrates, other bacteria convert nitrogen into ‘ammonium salts. The ionic equation for this second reaction is: N,+ 8H" +62" 2NH, ‘a Explain why thisis a reduction reaction. b_ Inthe presence of hydrogen ions, bacteria of a different type convert nitrate ions into nitro Give the ionic equation for this reaction, gasand water. ‘Ammonia is made by the Haber process using an iron catalyst. N,#3H, =22NH, (the forward reaction is exothermic) The raw materials for the Haber process can be obtained from the air and from natural gas. € What method is used to separate pure nitrogen from other gasesin the air? d__ Describe how hydrogen can be made from hydrocarbons. € State the essential conditions of temperature and pressure used for the Haber process,Chapter C9: industrial ir f Sketch an energy profile diagram to show both the catalysed and the uncatalysed reaction. Label the diagram to show the following key features: the reactants and products, the enthalpy change for the reac catalysed and uncatalysed reactions, and the Table 9.02 shows how the percentage of ammonia in the mixture leaving the reaction vessel varies under differen conditions eye) Preumrieee Perens Table 9.02 100 | 200 [300 45 5 7 9 18 3 so a 8 Use the grid provided to plot graphs of the percentage of ammonia against pressure at both 300°C and 500°CUse the checklist below to give yourself a mark for your graph. For each point, award yourself: + 2marksif you did it really well + Lmark if you made a good attempt at it, and partly succeeded + Omarks if you did not try to doiit, or did not succeed. Self-assessment checklist for graphs: enn the axes with a ruler, using most of the width and height have used a good scale for the x-axis and the y-axis, going up in Useful proportions. fou have labelled the axes correctly, giving the correct units for the th axes. | scales on be You have plotted each point precisely and correctly, have used a small, neat dot or cross for each point. have dr using aru | va single, clear best-fit line through each set of points ler for any straight line. [ Total (out of 14) 10-11 Good. re od start, bu 5-6 Poor. Ty this have ignored any anomalous results w 1en drawing the line, need to improve quite a bit graph again, using a new sheet of graph paper. 1-4 Very poor. Read through all the criteria again, and then try the sam iat is the percentage of ammonia formed at 250 atinand 300°C 1 Use your graphs to estimate the percentage of ammonia formed at 400°C and 250 atm, J The advantage of usin smperature isthe large percentage of ammonia formed. disadvantage of using a low temperature? hati the ke Suggest two advantages of using high pressure in the manufacture of ammonia,oem ME ae Ueno) The mostimportant use of ammonia is in fertiliser production. Fertilisers are added to the soll to improve crop yields. A farmer has the choice of two fertilisers, ammonium nitrate, NH,NO,, or diammonium hydrogen phosphate, (NHJ,HPO, 1 Show by calculation which of these fertilisers contains the greater percentage of nitrogen by mass. nth 'm State one major problem caused when the nitrates from fertilisers leach from the soll into streams and rivers, Exercise C9.04 Making sulfuric a dustrially This exercise helps your understanding of chemical equilibria, particularly the factors involved in the Contact process. The diagram shows the three different stages in the manufacture of sulfuric acid. catayst beds converier absorbe One possible source of sulfuris an ore containing zinc sulfide, ZnS. In the furnace, this sulfide ore is heated in oxygen to make zinc oxide, ZnO, and sulfur dioxide, Write an equation for this reaction. Inthe converter, sulfur dioxide and oxygen are passed over a series of catalyst beds ata temperature of about 420 °C 280,(g) + 0,(g) =e 250,(g) ‘AH=-196 kd (the reaction is exothermic) b An increase in pressure increases the yield of sulfur trioxide. Explain the reason for this effect € Even though an increase in pressure increases the yield of sulfur trioxide, the reaction in the converter is carried out at atmospheric pressure. Suggand Co-ordina d_ Insome sulfuric acid plants, the gases are cooled when they pass from one catalyst bed to the next. Use the information given about the nature of the reaction to explain why the gases need to be cooled. Exercise C9.05 Concrete chemistry This exercise will aid your recall of the important uses of limestone and help your familiarity with questions asked in an unusual context. Limestone is an important mineral resource. One use isin the making of cement. Cementis made by heating clay with crushed limestone. During this process (illustrated In diagram below), the calcium carbonate is first converted tocalcium oxide. CaCO, a0 +0, ‘a What name is given to this type of chemical reaction? ‘om cement, sand and water. When it has set, concrete is slightly porous. Rainwater can soak into concrete and some of the unreacted calcium oxide present dissolves to form calcium hydroxide esto mixtheclay powdered fotary in made of tee ‘bout 100 m + aa oem dione lin powdered [7 Y raveceme lumps wpndto crssned stone cody tose b_ Write an equation for the reaction that produces calcium hydroxide.ogee a eur ee ues) The aqueous calcium hydroxide in wet concrete is able t react with cart 10n dioxide in the air. Ca(OH), + C0,-> Caco, e diagram shows how the pH can vary at different points inside a cracked cont ete beam, EEE — 0123 ee ns surface of beam may Describe the change in pH from the surface to the centre of the beam, and explain why this. Describe briefly two other uses for limestone in addition to making cement.d and Co-ordinate Exercise C9.06 The chlor-alkali industry This exercise is concerned with the industrial electrolysis of brine and emphasises the usefulness and wide range of the products formed by this process (see diagram below). The electrolysis of brine is arguably one ofthe most efficient industrial processes. This stems from the fact thatall of the major products act as the starting points for the manufacture of other useful chemicals. The essentially no waste product from the process. used tormoking etergents seas sed for making ‘morprine ‘on trogen chloride and hydrochloric aid ‘a The starting point for this industrial process is a concentrated brine solution (the term ‘brine’ is explai Inthe coursebook) i Whatisbrine? Hi What are the three major products of the electrolysis of brine? List them below and write their namesin on the diagram above, 'b Twoof the products of the electrolysis can be reacted together to produce sodium chlorate() and sodium chlorate(y). These are commercial products that are sold as bleach and weedkiller respectively 1 Complete the following word equation for the production of sodium chlorate(). f ' > sodium + sodium + water chlorate() chlor li Sodium chlorate() is used asa bleach but also as treatment for the domestic water supply and swimming pools. Whatis the purpose of this treatment? iii Sodium chlorate(y)is an ionic compound made up of sodium ions and chlorate( ions (CI0,").Whatis the formula of sodium chiorate(y)?Chapter C9: Industrial inorganic ch Iv Thetwo gases produced in the electrolysis of brine can be reacted together to form hydrogen chloride, \Write the word and balanced symbol equations for this reaction. The membrane cell for the electrolysis of brine is shown in he following diagram, product Bout product cout membrane product Aout node cathode i. Whatisthe purpose of the membrane in the electrolysis cell? ji Whyisthe anode made of titanium? Hii Write the half-equations for the reactions taking place at the anode and cathode. Include state symbols in your equations, At the anode: Atthe cathode Chlorine is reacted ethene to pre ious hydrocarbons to produce useful solvents. For example, chlorine react \ce 1,2-dichloroethane, i What type of reaction i this? What isthe structural formula of 1,2-dichloroOrganic chemistry CE Exercise C10.01 Families of hydrocarbons This exercise helps you revise the key features of the families of hydrocarbons and develops your understanding of the structures of organic compounds. ‘a Complete the passage using only words from the lis. bromine alkanes hydrogen double chlorine chains —_petroleum methane —ethene_-—ethane colourless propane _—_ alkenes The chief source of organic compounds isthe naturally occurring mixture of hydrocarbons known as Hydrocarbons are compounds that contain carbon and soo OF There are many hydrocarbons because of the ability of carbon atoms to join together to form U0ng...ssseeennne THeTe is a Series of hydrocarbons with ust single covalent bonds between the carbon atoms in the molecule. These are saturated hydrocarbons, and they are called 2 The simplest of these turated hydrocarbons has the formula CH, and is called Unsaturated hydrocarbons can also occur. These molecules contain atleast one carbon-carbon. bond,eta These compounds belong to the. sessneusd S@CONG Series of hydrocarbons, The simplest of this ‘family’ of unsaturated hydrocarbons has the formula C,H, and is known as 4 The test for an unsaturated hydrocarbon is to add the sample t water. Itchanges colour from orange/brown to the hydrocarbon is unsaturated. b Table 10.01 shows the names, formulae and boiling points of the first members of the homologous series of unsaturated hydrocarbons. Complete the table by fillingin the spaces. CH 102 per ci 8 [botene Cat 7 pentene | GH 2 rea Teble1001 € Deduce the molecular formula of the alkene which has a relative molecular mass of 168, Exercise C10.02 Unsaturated hydrocarbons (the alkenes) GB This exercise develops your understanding of unsaturated hydrocarbons using an unfamitiar example. Limonene is a colourless unsaturated hydrocarbon found in oranges and lemons, The structure of limonene is shown in the diagram a Onthe structure, draw a circle around the bonds which make limonene an unsaturated hydrocarbon, b_ Whatiis the molecular formula of limonene?E Combined and The diagram shows how limonene can be extracted from lemon peel by steam distillation a Sa d State the name of the pieces of apparatus labelled A, B and C. A 8 c When limonene undergoes incomplete combustion, carbon monoxideis formed, @ What do you understand by the term incomplete combustion’? f State an adverse effect of carbon monoxide on health & Allhydrocarbons are covalently bonded whether saturated or un: ‘dot-and-cross’ diagrams for methane and ethane illustrating the arrangement of the bonding electrons. You only need to draw the outer electrons of the carbon atoms.Exercise C10.03 The alcohols as fuels ‘The following exercise uses information relating to the alcohols to develop your understanding of these compounds and to enhance your presentation, analysis and interpretation of experimental data concerning their property as fuels. Table 10.02 shows the formulae of the first three members of the alcohol homologous series. methanol | CH,OH than 40H ‘a. Use the information given to deduce the general formula for the alcohol ettranol i] HOH homologs sce [preparer [H.0H Table 10.02 Ethanol, the most significant of the alcot Is, can be manufactured from either ethene or glucose. b_ Write an equation for the indu the reaction takes place. trial production of ethanol from ethene and state the conditions under which The fermentation (anaerobic respiration) of glucose by yeast can be represented by the following equation. The reaction is catalysed by the enzyme zymase. After a few days, the reaction stops. Ithas produced a 12% aqueous solution of ethanol CH 04> 26,H,OH + 200, Sketch a labelled diagram to show how fermentation can be carried out. Suggest a reason why the reaction stops after a few days.Cambridg ‘© Whyisit essential that there is no oxygen in the reaction vessel? f Name the products of the complet sombustion of ethanol plain why et renewable fuel 'anol made from ethene is a non-renewable fuel, but that made from glucose is a {student used the apparatus shown in the diagram below to investigate the amount of heat produced when ethanol was burnt. thermometer copper calorimeter Draw the structure of ethanol showing all atoms and bonds. 1 Complete the equation for the complete combustion of ethanol GyHOH+30,—>, c0,+ H,0 J When 2.3 gof ethanol are burnt, 7 go ethanol are burnt. 9f water are formed. Calculate the mass of water formed when 13.8 gof The experiment was later adap! to compare the heat released by burning four different alcohols, Each burner ir turn was weighed and then the alcohol was allowed to burn until the temperature of the water had risen by 15 he flame was then extinguished and the burner re-weighed. The results obtained are shown in Table 10.03methanol CH,OH ethanol GHJOH propan-l-ol__[C,H,OH | pentan-l-ol__[C.H,0H Table 10.03 k. Plot a graph showi i fequired varies ugh the points. Use the checklist below to give yourself a mark for your graph. For each point, award yourself: + 2marks if you did it really well + Lmark ifyou made a good attempt at it, and partly succeeded + Omarks if you did not try to doit, or not succeed. Self-assessment checklist for graphs: con You have drawn the axes with a ruler, using most of the width and height of the grid ‘carbon atomsiin the alcohol used. Draw a smooth curve Wee ness arded You have used a good scale for the x-axis and the y-axis, going up in useful proportions. You have label 3d the axes correctly, giving the correct he scales on both axes. You have plott each point pr ely and correctly You have used a small, neat cross or each point. You have drawn a single, clear bestit line through the points You have ignor line, sd any anomalous results 1en drawing the Total (out of 14) 12-14 Excellent 10-11 Good, 19 start, but you need to improve quite a bit. 5-6 Poor. Try this same graph again, using an 1-4 Very poor. Read through all the heet of graph paper. ain, and then try the same graph again,Re Predict the mass of butanol, C,H,0H, which, on combustion, would raise the temperature of the why the same temperature rise (15°C) was used in each exper Exercise C10.04 Hydrocarbons and their reactions This exercise is aimed at developing your confidence in discussing aspects of the chemistry of the hydrocarbons, particularly their use as fuels. a Complete Table 10.04, (Relative atomic masses: H= 1, ethene ene) oeeteacuteen ic \carbon ethane Meme eet Een cal eee eas ater after being shaken colourless Renee Table 10.04 b The hydrocarbon propane isan imp propane in an excess of air, give: nstituent of the fuel liquid petr 1 aword equation i abalanced symbol equation. Use your answer to give the number of moles of ater formed propaneis burntin a