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Water QP - Merged

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18 views103 pages

Water QP - Merged

Uploaded by

jliew2024

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1 (a) Describe a chemical test which shows the presence of water.

test .......................................................................................................................

colour change if water is

present ...............................................................................................
........................................................................................................................................
[3]

(b) How could you show that a sample of water is pure?

.......................................................................................................................................[1]

........................................................................................................................................

................................................................................................................................... [2]

(d) State two industrial uses of water.

........................................................................................................................................

.................................................................................................................................... [2]

[Total: 8]

PhysicsAndMathsTutor.com
2 (a) Water is needed for industry and in the home.

(i) Rain water is collected in reservoirs. How is it treated before entering the water supply?

.............................................................................................................................................

....................................................................................................................................... [2]

(ii) State two industrial uses of water.

.............................................................................................................................................

....................................................................................................................................... [2]

(iii) State two uses of water in the home.

.............................................................................................................................................

....................................................................................................................................... [1]

(b) In many regions, drinking water is obtained by the distillation of sea-water. Explain how
distillation separates the water from sea-water.

....................................................................................................................................................

.............................................................................................................................................. [2]

[Total: 7]

PhysicsAndMathsTutor.com
3 The diagram below shows part of the Water Cycle.

cloud
H2O(l) H2O(g)
Sun
rain

land

H2O(l) sea

(a)
a) State the name of each of the following changes of state.

H2O(l) → H2O(g)

name ..........................................................................................................................

H2O(g) → H2O(l)

name ..........................................................................................................................
[2]

(ii) Which one of the above changes of state is exothermic? Explain your choice.

....................................................................................................................................

.............................................................................................................................. [1]

(b) The rain drains into rivers and then into reservoirs. Describe how water is treated before
it enters the water supply.

...........................................................................................................................................

..................................................................................................................................... [2]

....................................................................................................................................

.............................................................................................................................. [4]

PhysicsAndMathsTutor.com
(ii) Fish live in water which is neutral (neither acidic nor alkaline). Acid rain decreases
the pH of water in lakes and rivers. Both of the bases, calcium oxide and calcium
carbonate, can neutralise this acid and increase the pH. Explain why calcium
carbonate is a better choice.

....................................................................................................................................

.............................................................................................................................. [2]

[Total: 11]

PhysicsAndMathsTutor.com
4 Ozone is a form of oxygen. Ozone is present in the upper atmosphere and it prevents
dangerous solar radiation from reaching the Earth’s surface. Some of the chemicals that
diffuse into the upper atmosphere decompose ozone. Chemicals that have this effect are
methane (CH4), chloromethane (CH3Cl ) and an oxide of nitrogen (NO2).

(i) Which of these three chemicals diffuses the most slowly? Give a reason for your
choice.

....................................................................................................................................

.............................................................................................................................. [2]

(ii) Chloromethane is formed when seaweed decomposes. Name the compounds in the
environment from which seaweed might have obtained the following elements:

carbon; .......................................................................................................................

hydrogen; ...................................................................................................................

chlorine. ................................................................................................................ [3]

(iii) How can chloromethane be made from methane?

reagent .......................................................................................................................

condition ............................................................................................................... [2]

PhysicsAndMathsTutor.com
(iv) The oxides of nitrogen are atmospheric pollutants. Describe how they are formed.

....................................................................................................................................

.............................................................................................................................. [2]

(v) Complete the equation for the decomposition of ozone.

............... O3 → ...............
[2]

[Total: 11]

PhysicsAndMathsTutor.com
5 (a The major gases in unpolluted air are 79 % nitrogen and 20 % oxygen.

(i) Name another gaseous element in unpolluted air.

[1]

(ii) Name two compounds in unpolluted air.

[2]

(b) Two common pollutants in air are carbon monoxide and the oxides of nitrogen.

(i) Name another pollutant in air.

[1]

(ii) Describe how carbon monoxide is formed.

[2]

(iii) How are the oxides of nitrogen formed?

[2]

(iv) Explain how a catalytic converter reduces the emission of these two gases.

[2]

[Total: 10]

PhysicsAndMathsTutor.com
6 This question is concerned with the following oxides.

sulfur dioxide
carbon monoxide
lithium oxide
aluminium oxide
nitrogen dioxide
strontium oxide

(a)
a) Which of the above oxides will react with hydrochloric acid but not with aqueous
sodium hydroxide?

.............................................................................................................................. [1]

(ii) Which of the above oxides will react with aqueous sodium hydroxide but not with
hydrochloric acid?

.............................................................................................................................. [1]

(iii) Which of the above oxides will react with both hydrochloric acid and aqueous sodium
hydroxide?

.............................................................................................................................. [1]

(iv) Which of the above oxides will not react with hydrochloric acid or with aqueous
sodium hydroxide?

.............................................................................................................................. [1]

(b) Two of the oxides are responsible for acid rain.

Identify the two oxides and explain their presence in the atmosphere.

...........................................................................................................................................

..................................................................................................................................... [5]

PhysicsAndMathsTutor.com
(c) Lithium oxide is an ionic compound.

(i) Identify another ionic oxide in the list on page 3.

.............................................................................................................................. [1]

(ii) Draw a diagram which shows the formula of lithium oxide, the charges on the ions
and the arrangement of the valency electrons around the negative ion.
Use x to represent an electron from an atom of oxygen.
Use o to represent an electron from an atom of lithium.

[2]

[Total: 12]

PhysicsAndMathsTutor.com
7 The diagram shows part of the carbon cycle. This includes some of the processes which
determine the percentage of carbon dioxide in the atmosphere.

carbon dioxide
in the atmosphere

combustion respiration

photosynthesis

(i) Carbon dioxide is one greenhouse gas. Name another one.

.............................................................................................................................. [1]

(ii) Explain the term respiration and how this process increases the percentage of
carbon dioxide in the atmosphere.

....................................................................................................................................

.............................................................................................................................. [3]

(iii) Explain why the combustion of waste crop material should not alter the percentage
of carbon dioxide in the atmosphere.

....................................................................................................................................

.............................................................................................................................. [2]

(iv) In 1960 the percentage of carbon dioxide in the atmosphere was 0.032% and in
2008 it was 0.038%. Suggest an explanation for this increase.

....................................................................................................................................

.............................................................................................................................. [2]

[Total: 8]

PhysicsAndMathsTutor.com
Question Answer Marks

1(a) cobalt chloride (paper) / anhydrous cobalt chloride / CoCl 2; 3

from blue;
to pink;
or
copper sulfate / anhydrous copper sulfate / CuSO4;
from white;
to blue;
1(b) boils at 100 °C / boiling point 100 °C / freezes at 0 °C / freezing point 0 °C / melts at 0 °C / melting point 0 oC; 1
1(c) any two from: 2
• filtration / sedimentation / sieving / screening / (pass through) gravel (beds) / flocculation / decantation / clarification /
coagulation / flotation / settling tank / add aluminium sulfate;
• (add) carbon;
• chlorination / (add) chlorine / add Cl 2;
• fluoridation / add fluoride;
• ozone dosing;
• desalination;
• aeration;
• distillation;
1(d) any two from: 2
making steel; making paper; textiles; generating electricity / energy / power / turbines; HEP; water mills; steam power (e.g.
steam engines); geothermal power; agriculture; livestock; irrigation; hydration of alkenes / manufacture of ethanol / alcohols;
manufacture of sulfuric acid / Contact process; manufacture of hydrogen; solvent / dissolving; coolant / cooling;
cleaning / washing; (supply of) drinking (water); central heating; production of slaked lime; cooking;

PhysicsAndMathsTutor.com
2 (a (i) filtration (1)

chlorination (1) [2]

(ii) Any two from: [2]

• manufacture of ethanol
• used in the manufacture of sulfuric acid or in the Contact process
• manufacture of hydrogen or ammonia or for the Haber process

(iii) Any two from: [2]

• cooking
• washing or laundry
• drinking
• toilets
• watering plants
• (domestic) heating

(b) boiling or turning to steam (1)

then condensing / condensation (1) [2]

[Total: 7]

PhysicsAndMathsTutor.com
3 (a (i) evaporation / boiling / vaporisation / evaporate / vaporise; [1]
condensation / liquefaction / condense / liquefy; [1]

(ii) condensation accept: correct equation H2O(g)→H2O(l)

because energy / heat is given out / gas has more energy than liquid / need to supply
energy to change liquid to gas so reverse must give out energy / bonds form; [1]

(b) chlorination / chlorine to kill microbes; [1]

filtration or filter; [1]

accept: sedimentation or sand or gravel or grit

(c) (i) combustion of fossil fuels; [1

(which contain) sulfur; [1]
sulfur dioxide formed; [1]
(reacts in air / with water to form) sulfurous / sulfuric acid; [1]
OR
nitrogen and oxygen in air; [1]
react at high temperatures / in engines; [1]
to form oxides of nitrogen or named oxide of nitrogen; [1]
(reacts in air / with water to form) nitrous / nitric acid; [1]
[max 4]

(ii) calcium oxide is soluble in water / reacts with water to form

calcium hydroxide; [1]
pH above 7 / the water becomes alkaline; [1]
OR
calcium carbonate insoluble in water; [1]
pH cannot be above 7 / water is neutral / does not make water alkaline; [1]
[max 2]

[Total: 11]

PhysicsAndMathsTutor.com
4 (i chloromethane [1]
cond biggest molecular mass / biggest mass of one mole / its molecules
move slowest / heaviest molecule / highest density [1]
accept atomic mass if correct numerical value given
ignore it is the heaviest (gas) / biggest molecule
accept particles or molecules
not atoms

(ii) carbon dioxide / calcium carbonate [1]

not methane
water [1]
sodium chloride / brine / seawater [1]

(iii) chlorine [1]

not chlorine water
cond light / UV / heat / high temperature if numerical value given about
200oC / lead tetraethyl [1]
not warm

(iv) oxygen and nitrogen (in air) [1]

not from fuel, negates mark 1
(react) at high temperatures / lightning / in engine [1]
not combustion or exhaust, negates mark 2

(v) 2O3 3O2 [2]

not balanced = [1]

PhysicsAndMathsTutor.com
5 (a (i) argon or krypton or helium [1]
Accept xenon and radon even though percentages are very small
NOT hydrogen

(ii) water and carbon dioxide [2]

(b) (i) sulfur dioxide or lead compounds or CFCs or methane or particulates

or unburnt hydrocarbons or ozone etc. [1]

(ii) incomplete combustion [1]

of a fossil fuel or a named fuel or a fuel that contains carbon [1]

(iii) at high temperature or inside engine [1]

nitrogen and oxygen (from the air) react [1]

(iv) it changes carbon monoxide to carbon dioxide [1]

oxides of nitrogen to nitrogen [1]

OR symbol or word equation of the type:

2NO + 2CO → CO2 + N2 [2]

OR a redox explanation – the oxides of nitrogen oxidise carbon monoxide to carbon

dioxide, [1]
they are reduced to nitrogen [1]

OR 2NO → N2 + O2 [1]
2CO + O2 → 2CO2 [1]

[Total: 10]

PhysicsAndMathsTutor.com
6 (a (i) lithium oxide / strontium oxide [1]

(ii) sulfur dioxide / nitrogen dioxide [1]

(iii) aluminium oxide [1]

(iv) carbon monoxide [1]

accept: correct formulae

(b) sulfur dioxide [1]

burn (fossil) fuel containing sulfur / volcanoes [1]
nitrogen dioxide [1]
reaction of nitrogen and oxygen [1]
high temperatures / in car engine [1]
not: exhaust

(c) (i) strontium oxide [1]

accept: aluminium oxide

(ii) use correct formula [1]

cond: charges on ions
6x and 2o around oxygen [1]
ignore: electrons around Li

PhysicsAndMathsTutor.com
7 (i) methane / water vapour / oxides of nitrogen / hydrofluorocarbons / perfluorocarbons /
ozone [1]
not sulfur dioxide

(ii) living organisms / plants and animals / cells [1]

produce energy (from food / glucose / carbohydrates) [1]
this forms carbon dioxide (could be in an equation) [1]

(iii) when growing the crop removed carbon dioxide from atmosphere [1]
/ crop photosynthesised and used carbon dioxide
combustion returned the carbon dioxide [1]

(iv) increased combustion [1]

of fossil fuels / named fossil fuel [1]

or deforestation [1]
less photosynthesis [1]
not greater population
[Total: 8]

PhysicsAndMathsTutor.com
1 Clean dry air contains mainly nitrogen and oxygen.

(a) Name two other gases that are in clean dry air.

....................................................................................................................................................

.............................................................................................................................................. [2]

(b) Air often contains pollutants.

Identify three common gaseous pollutants in air and state how each of these pollutants are
produced.

pollutant gas 1 ...........................................................................................................................

how it is produced ......................................................................................................................

....................................................................................................................................................

pollutant gas 2 ...........................................................................................................................

how it is produced ......................................................................................................................

....................................................................................................................................................

pollutant gas 3 ...........................................................................................................................

how it is produced ......................................................................................................................

....................................................................................................................................................
[6]

[Total: 8]

PhysicsAndMathsTutor.com
2 This question is about compounds of nitrogen.

(a) (i) Describe the Haber Process giving reaction conditions and a chemical equation.
Reference to rate and yield is not required.

.............................................................................................................................................

....................................................................................................................................... [5]

(ii) Give one use of ammonia.

....................................................................................................................................... [1]

(b) The diagram shows the structure of a hydrazine molecule.

H H

N N

H H

Draw the electron arrangement of a hydrazine molecule. Show the outer shell electrons only.

[2]

(c) Hydrazine is a base.

(i) Define the term base.

....................................................................................................................................... [1]

(ii) Complete the chemical equation to show that hydrazine acts as a base when added to
water.

N2H4 + H2O → .............. + .............. [1]

PhysicsAndMathsTutor.com
(d) Nitrogen dioxide is an atmospheric pollutant.

(i) State one environmental problem caused by nitrogen dioxide.

....................................................................................................................................... [1]

(ii) Explain how oxides of nitrogen, such as nitrogen dioxide, are formed in car engines.

.............................................................................................................................................

....................................................................................................................................... [2]

[Total: 13]

PhysicsAndMathsTutor.com
3 (a) Polluted air contains two oxides of carbon and two oxides of nitrogen. A major source
of these pollutants is motor vehicles.

(i) Describe how carbon dioxide and carbon monoxide are formed in motor vehicle engines.

.............................................................................................................................................

....................................................................................................................................... [3]

(ii) State one adverse effect of each of these gases.

.............................................................................................................................................

....................................................................................................................................... [2]

(iii) Nitrogen monoxide, NO, is released by motor vehicle exhausts.

Explain how nitrogen monoxide is formed in motor vehicle engines.

.............................................................................................................................................

....................................................................................................................................... [2]

PhysicsAndMathsTutor.com
(iv) When nitrogen monoxide is released into the atmosphere, nitrogen dioxide, NO2, is formed.

Suggest an explanation why this happens.

....................................................................................................................................... [1]

(b) Predict the possible adverse effect on the environment when this non-metal oxide, NO2, reacts
with water and oxygen.

....................................................................................................................................................

.............................................................................................................................................. [2]

(c) How are the amounts of carbon monoxide and nitrogen monoxide emitted by modern motor
vehicles reduced? Include an equation in your answer.

....................................................................................................................................................

.............................................................................................................................................. [3]

[Total: 13]

PhysicsAndMathsTutor.com
4 Three common pollutants in the air are carbon monoxide, the oxides of nitrogen, NO and NO2, and
unburnt hydrocarbons. They are all emitted by motor vehicles.

(a) Describe how the oxides of nitrogen are formed.

....................................................................................................................................................

.............................................................................................................................................. [2]

(b) Describe how a catalytic converter reduces the emission of these three pollutants.

....................................................................................................................................................

.............................................................................................................................................. [4]

....................................................................................................................................................

.............................................................................................................................................. [1]

[Total: 7]

PhysicsAndMathsTutor.com
5 Air is a mixture of gases. The main constituents are the elements oxygen and nitrogen.

(a) (i) Name another element in air.

.............................................................................................................................. [1]

(ii) Give the formula of a compound in unpolluted air.

.............................................................................................................................. [1]

(b) Common pollutants present in air are the oxides of nitrogen and sulfur dioxide.

(i) How are the oxides of nitrogen formed?

....................................................................................................................................

.............................................................................................................................. [2]

(ii) How is sulfur dioxide formed?

....................................................................................................................................

.............................................................................................................................. [2]

(iii) These oxides are largely responsible for acid rain.

State two harmful effects of acid rain.

....................................................................................................................................

.............................................................................................................................. [2]

PhysicsAndMathsTutor.com
(c) The percentage of oxygen in air can be determined by the following experiment.

large pile of small pile

copper of copper

gas syringe gas syringe

heat
containing
50 cm3 of air

The gas syringe contains 50 cm3 of air. The large pile of copper is heated and the air is
passed from one gas syringe to the other over the hot copper. The large pile of copper
turns black. The gas is allowed to cool and its volume measured.

The small pile of copper is heated and the remaining gas passed over the hot copper.
The copper does not turn black. The final volume of gas left in the apparatus is less
than 50 cm3.

(i) Explain why the copper in the large pile turns black.

....................................................................................................................................

.............................................................................................................................. [2]

(ii) Why must the gas be allowed to cool before its volume is measured?

.............................................................................................................................. [1]

(iii) Explain why the copper in the small pile did not turn black.

.............................................................................................................................. [1]

(iv) What is the approximate volume of the gas left in the apparatus?

.............................................................................................................................. [1]

[Total: 13]

PhysicsAndMathsTutor.com
6 (a) State a use for each of the following gases.

(i) chlorine ................................................................................................................ [1]

(ii) argon ................................................................................................................... [1]

(iii) ethene .................................................................................................................. [1]

(iv) oxygen ................................................................................................................. [1]

(b) Describe how oxygen is obtained from air.

...........................................................................................................................................

..................................................................................................................................... [2]

[Total: 6]

PhysicsAndMathsTutor.com
Question Answer Marks

1(a) any 2 from: 2

carbon dioxide;
nitrogen;
any named noble gas;
1(b) any 6 from: 6

carbon monoxide;
from incomplete combustion (of carbon-containing fuel);

sulfur dioxide;
from burning fossil fuels / roasting ores which contain sulphur / volcanoes;

oxides of nitrogen;
nitrogen reacting with oxygen in car engines / lightning;

methane;
from anaerobic decomposition / anaerobic decay;

PhysicsAndMathsTutor.com
Question Answer Marks

2(a)(i) more than enough to react (with all the hydrocarbon); 1

OR
(some) oxygen remaining;
a)(ii) cm3; 1
(a)(iii) 2 : 15 : 10; 1
(a)(iv) 2
2 : 15 : 10 : 10; 1
C5H10; 1
(b)i) 7H16; 1
(b)(ii) contains a double bond / triple bond / multiple bond; 1
OR
not all bonds are single bonds;
(b)(iii) 2
test: aqueous bromine / bromine (water) / Br2; 1
result: (orange / yellow / brown) to colourless / decolourised / colour disappears; 1
2(c)(i) add 1
(c)(ii) (kg); 1
(c)(iii) 2
propene: CH2; 1
polypropene: CH2; 1

PhysicsAndMathsTutor.com
Question Answer Marks

3(a)(i) com / burning of a motor vehicle fuel or a named fuel which can act as a motor vehicle fuel; 3
incomplete combustion would produce CO;
complete combustion would produce CO2;
(a)(ii) carbon dioxide: climate change / global warming / greenhouse effect; 2
carbon monoxide: poisonous / toxic;
(a)(iii) nitrogen and oxygen react or combine; 2
at high temperatures or in presence of spark;
(a)(iv) it reacts or combines with oxygen / NO + ½O2 → NO2; 1
(b) any two from: 2
• acid rain is formed;
• lowers pH or acidifies lakes / rivers or kills fish / aquatic animals;
• changes composition of soils or reduces fertility of soil or reduces crop yields / deforestation or kills crops or trees or
plants or leaves / lowers pH of soil or increases acidity of soil;
• attacks (limestone) buildings or statues;
attacks metal (structures) / bridges;

Question Answer Marks

(c) use of a catalytic converter; 3

2NO + 2CO → 2CO2 + N2

species;
balancing;

PhysicsAndMathsTutor.com
4 (a nitrogen and oxygen react [1]
at high temperatures (in engine) [1]

(b) M1 carbon monoxide (converted to) carbon dioxide or 2CO + O2 → 2CO2 [1]

M2 (by) oxides of nitrogen (which are reduced to) nitrogen

or 2NO → N2 + O2 or 2NO2 → N2 + 2O2 [1]

M3 hydrocarbons (burn) making water [1]

M4 products: any two from:

carbon dioxide, water, nitrogen [1]

[Total: 7]

PhysicsAndMathsTutor.com
5 (a (i) named noble gas [1]
accept: any noble gas
accept: symbol

(ii) H2O / CO2 [1]

not: names not: equations

(b)
b) oxygen and nitrogen (in air) (react) [1]
at high temperature [1]
accept: in engines / lightning not: in exhausts

(ii) fossil fuels / fuels which contain sulfur [1]

accept: named fossil fuel such as coal / oil / natural gas
burn / combust [1]

(iii) any two from:

damage buildings / soil acidification / leaching from soil / soil nutrients become
unavailable / kill microbes / acidify lakes / kill fish / damage trees / reduction in plant
growth / crop loss [2]

(ii) measure volume at room temperature / gas has different volumes at different
temperatures / volume of gas depends on temperature / hot gas has higher volume /
heat causes expansion (of gases) / ORA [1]

(iii) no oxygen left or all the oxygen has reacted (with copper) [1]

(iv) 39–40 cm3 note: units required [1]

6 (a (i) manufacture of plastics / (solvents for) dry cleaning / metal degreasing / textiles
/ agrochemicals / pharmaceuticals / insecticides / dyestuffs / household cleaning
products / bleach / water treatment / swimming pools / kill bacteria or germs or
microorganisms or pathogens / sterilisation / disinfectants; [1]

(ii) electric light bulbs / fluorescent tubes / (inert gas shield for) arc welding /
production of titanium / inert atmosphere / car headlights / food packaging; [1]

(iii) (manufacture of) polyethene / polyvinyl chloride (PVC) / making polymers / (to
prepare) epoxyethane (which is used in the manufacture of detergents / (to
make) ethylene glycol (which is used to prepare Terylene) / (to make) anti-
freeze / or making ethanol (accept making alcohol) / ripening fruits; [1]

(iv) (making) steel / (oxy-acetylene) welding / cutting of metals / medical or diving or

(oxygen tanks in) hospitals / astronauts / (deep sea) diving / fire fighters;
[1]

(b) liquid air; [1]

fractional distillation; [1]

[Total: 6]

PhysicsAndMathsTutor.com
1 Ammonia is made by the Haber process.

N2(g) + 3H2(g) 2NH3(g)

The forward reaction is exothermic.

Typical reaction conditions are:

• finely divided iron catalyst,

• temperature 450 °C,
• pressure 200 atmospheres.

(a) Explain why the catalyst is used as a very fine powder and larger pieces of iron are not used.

....................................................................................................................................................

.............................................................................................................................................. [2]

(b) Using the above conditions, the equilibrium mixture contains about 15% ammonia.

State two changes to the reaction conditions which would increase the percentage of
ammonia at equilibrium.

....................................................................................................................................................

.............................................................................................................................................. [2]

....................................................................................................................................................

.............................................................................................................................................. [2]

[Total: 6]

PhysicsAndMathsTutor.com
2 Plant growth is improved by the availability of essential elements, such as nitrogen, and by the soil
having a suitable pH.

(a) Nitrogen-based fertilisers are made from ammonia. Ammonia is manufactured by the Haber
process.

(i) Describe the Haber process giving reaction conditions and a balanced equation.
(Do not discuss reaction rate and yield.)

.............................................................................................................................................

....................................................................................................................................... [5]

(ii) Fertilisers contain nitrogen.

Name the other two elements essential for plant growth commonly found in fertilisers.

....................................................................................................................................... [2]

(b) Crops do not grow well if the soil is too acidic.

(i) One cause of acidity in soil is acid rain. Explain how acid rain is formed.

.............................................................................................................................................

....................................................................................................................................... [3]

(ii) Name two bases which are used to increase the pH of acidic soils.

....................................................................................................................................... [2]

[Total: 12]

PhysicsAndMathsTutor.com
3 The reactivity series shows the metals in order of reactivity.

(a) The reactivity series can be established using displacement reactions. A piece of zinc is
added to aqueous lead nitrate. The zinc becomes coated with a black deposit of lead.

Zn + Pb2+ → Zn2+ + Pb

Zinc is more reactive than lead.

The reactivity series can be written as a list of ionic equations.

...... → ...... + ...... most reactive metal : the best reductant (reducing agent)
Zn → Zn2+ + 2e–
Fe → Fe2+ + 2e–
Pb → Pb2+ + 2e–
Cu → Cu2+ + 2e–
Ag → Ag+ + e–

(i) In the space at the top of the list, write an ionic equation for a metal which is more
reactive than zinc. [1]

(ii) Write an ionic equation for the reaction between aqueous silver(I) nitrate and zinc.

.............................................................................................................................. [2]

(iii) Explain why the positive ions are likely to be oxidants (oxidising agents).

.............................................................................................................................. [1]

(iv) Deduce which ion is the best oxidant (oxidising agent).

.............................................................................................................................. [1]

(v) Which ion(s) in the list can oxidise lead metal?

.............................................................................................................................. [1]

PhysicsAndMathsTutor.com
(b) A reactivity series can also be established by measuring the voltage of simple cells. The
diagram shows a simple cell.

voltmeter
V

cadmium copper
electrode electrode

sulfuric acid

Results from cells using the metals tin, cadmium, zinc and copper are given in the table
below.

electrode 1 electrode 2
cell voltage / volts
positive electrode negative electrode

1 copper cadmium 0.74

2 copper tin 0.48
3 copper zinc 1.10

Write the four metals in order of increasing reactivity and explain how you used the data
in the table to determine this order.

...........................................................................................................................................

..................................................................................................................................... [3]

[Total: 9]

PhysicsAndMathsTutor.com
4 Ammonia is manufactured by the Haber process.

N2(g) + 3H2(g) 2NH3(g)

The forward reaction is exothermic.

(a) Describe how the reactants are obtained.

(i) Nitrogen

....................................................................................................................................

.............................................................................................................................. [2]

(ii) Hydrogen

....................................................................................................................................

.............................................................................................................................. [3]

(b) The percentage of ammonia in the equilibrium mixture varies with temperature and
pressure.

(i) Which pair of graphs, A, B or C, shows correctly how the percentage of ammonia at
equilibrium varies with temperature and pressure?

percentage percentage
pair A NH3 at NH3 at
equilibrium equilibrium

temperature pressure

percentage percentage
pair B NH3 at NH3 at
equilibrium equilibrium

temperature pressure

percentage percentage
pair C NH3 at NH3 at
equilibrium equilibrium

temperature pressure

The pair with both graphs correct is ................................................................. [1]

PhysicsAndMathsTutor.com
(ii) Give a full explanation of why the pair of graphs you have chosen in (i) is correct.

....................................................................................................................................

.............................................................................................................................. [6]

(iii) Catalysts do not alter the position of equilibrium. Explain why a catalyst is used in
this process.

....................................................................................................................................

.............................................................................................................................. [2]

[Total: 14]

PhysicsAndMathsTutor.com
5 (a) Nitric acid is now made by the oxidation of ammonia. It used to be made from air and
water. This process used very large amounts of electricity.

Air was blown through an electric arc and heated to 3000 °C.

N2(g) + O2(g) 2NO(g) equilibrium 1

nitric oxide

The equilibrium mixture leaving the arc contained 5 % of nitric oxide. This mixture was
cooled rapidly. At lower temperatures, nitric oxide will react with oxygen to form nitrogen
dioxide.

2NO(g) + O2(g) 2NO2 equilibrium 2

Nitrogen dioxide reacts with oxygen and water to form nitric acid.

(i) Suggest a reason why the yield of nitric oxide in equilibrium 1 increases with
temperature.

.............................................................................................................................. [1]

(ii) What effect, if any, would increasing the pressure have on the percentage of nitric
oxide in equilibrium 1? Explain your answer.

....................................................................................................................................

.............................................................................................................................. [2]

(iii) Deduce why equilibrium 2 is only carried out at lower temperatures.

....................................................................................................................................

.............................................................................................................................. [2]

(iv) Complete the equation for the reaction between nitrogen dioxide, water and oxygen
to form nitric acid.

........NO2 + O2 + ............ → ............HNO3 [2]

(v) Ammonia is more expensive than water and air. Suggest a reason why the
ammonia-based process is preferred to the electric arc process.

.............................................................................................................................. [1]

PhysicsAndMathsTutor.com
(b)
b) Nitric acid is used to make the fertiliser ammonium nitrate, NH4NO3.
What advantage has this fertiliser over another common fertiliser, ammonium sulfate,
(NH4)2SO4?

.............................................................................................................................. [1]

(ii) Plants need nitrogen to make chlorophyll. Explain why chlorophyll is essential for
plant growth.

....................................................................................................................................

.............................................................................................................................. [4]

[Total: 13]

PhysicsAndMathsTutor.com
6 Ammonia is made by the Haber process.

N2(g) + 3H2(g) 2NH3(g)

(a) State one major use of ammonia.

..................................................................................................................................... [1]

(b) Describe how hydrogen is obtained for the Haber process.

...........................................................................................................................................

..................................................................................................................................... [3]

(c) This reaction is carried out at a high pressure, 200 atmospheres.

State, with an explanation for each, two advantages of using a high pressure.

...........................................................................................................................................

..................................................................................................................................... [5]

(d)
d) What is the difference between an endothermic and an exothermic reaction?

....................................................................................................................................

.............................................................................................................................. [1]

PhysicsAndMathsTutor.com
(ii) Bond breaking is an endothermic process. Bond energy is the amount of energy
needed to break or form one mole of the bond. Complete the table and explain why
the forward reaction is exothermic.

N N + 3H H 2H N H

bond energy energy change exothermic

bond
kJ / mol kJ or endothermic

N N 944 +944 endothermic

H—H 436 3 × 436 = +1308
N—H 388

...........................................................................................................................................

..................................................................................................................................... [3]

[Total: 13]

PhysicsAndMathsTutor.com
1(a) large surface area / large area of contact / large surface;

more (successful) collisions (between catalyst and gases or between reacting 2 I activation energy
gases) OR more active sites OR faster reaction / increase rate / increase Second mark must be comparative
speed;
(b) decre temperature / temperature below 450 °C / quoted temperature below I comments about concentration
450 °C; I low temperature and high pressure. Both
increase pressure / pressure above 200 atm / quoted pressure above 200 atm; 2 answers must be comparative
I explanations
(c) decreased temperature would reduce rate / reaction slower / too slow; A takes longer
I slow (unqualified)

increased pressure expensive / uneconomic / safety risks / leaks / explosions / I answers that do not refer to decreased
yield or rate good enough at lower pressure / strong pipes needed / thick pipes temperature and increased pressure e.g. it is
needed / sturdy pipes needed / requires a lot of energy; 2 too expensive unless this is linked with
pressure

PhysicsAndMathsTutor.com
2 (a) (i) pressure 150–300 atmospheres / atm (1)

temperature accept in range 370 to 470 °C (1)

iron (catalyst) (1)

balanced equation N2 + 3H2 2NH3 (1)

equilibrium / reversible (1) [5]

(ii) potassium / K (1)

phosphorus / P (1) [2]

(b) (i) burn fossil fuels / burn fuels containing sulfur / burn compounds containing
sulfur / burn ores containing sulfur / roast metal sulfides / burn metal sulfides
(1)

sulfur dioxide / SO2 (formed) (1)

(form) sulfuric / H2SO4 / sulfurous acid / H2SO3 (1)

nitrogen and oxygen (in air) react at high temperatures / in jet engines / car
engines / lightning. (1)

(form) oxides of nitrogen (1)

(form) nitric acid / HNO3 / nitrous acid / HNO2 (1) [3]

(ii) any two from:

calcium oxide / lime / quicklime / CaO (1)
calcium hydroxide / Ca(OH)2 / lime / slaked lime / limewater (1)
calcium carbonate / CaCO3 / limestone / chalk / marble (1) [2]
guidance: ‘lime’ can only be credited once.

[Total: 12]

3 (a (i) any metal above zinc

Mg → Mg2+ + 2e [1]

(ii) Zn + 2Ag+ → Zn2+ + 2Ag [2]

Note: not balanced only [1]

(iii) because they can accept or gain electrons / change into atoms or can be reduced [1]

(iv) Ag+ or silver [1]

charge not essential but if given must be correct

(v) Ag+ and Cu2+ or silver and copper [1]

charge not essential but if given must be correct

PhysicsAndMathsTutor.com
(b) Cu Sn Cd Zn (i.e. all 4 in correct order) [1]
relates order to voltage [1]

one relevant comment from: [1]

higher reactivity metals are the negative electrode / copper is least reactive because it is the
positive electrode because copper would have the lowest voltage / copper cell V = 0 / the
bigger the difference in reactivity, the bigger the voltage / zinc has highest voltage because it
is most reactive / more reactive metals have higher voltage

[Total: 9]

4 (a (i) fractional distillation [1]

(liquid) air [1]

(ii) cracking / heat in presence of catalyst [1]

of alkane / petroleum [1]
to give an alkene and hydrogen [1]

OR: electrolysis (1)

named electrolyte (1)
hydrogen at cathode (1)

OR: from methane (1)

react water / steam (1)
heat catalyst (1)
only ACCEPT: water with methane or electrolysis

(b) (i) the pair with both graphs correct is C [1]

NOTE: mark (b)(ii) independent of (b)(i)

(ii) high pressure favours side with lower volume / fewer moles [1]
this is RHS / product / ammonia [1]
%NH3 / yield increases as pressure increases [1]

the forward reaction is exothermic [1]

exothermic reactions favoured by low temperatures [1]
%NH3 / yield decreases as temperature increases [1]
ACCEPT: reverse arguments

(iii) increases reaction rate [1]

ACCEPT: reduces activation energy [1]
OR: decreases the amount of energy particles need to react
OR: economic rate at lower temperature so higher yield
[Total: 14]

PhysicsAndMathsTutor.com
4 (a (i) the (forward) reaction is endothermic [1]

(ii) none [1]

volume of reactants and products the same [1]
ACCEPT: number of moles or molecules

(iii) the reaction (between oxygen and nitric oxide) is exothermic [1]
high temperatures push equilibrium to left / high temperatures decrease yield of products
/ low temperatures favour forward reaction [1]

(iv) 4NO2 + O2 + 2H2O 4HNO3 [2]

not balanced = (1) only

(v) (cost of) high amount of electricity / energy [1]

(b) (i) contains more nitrogen [1]

hot
(ii) photosynthesis
chlorophyll is catalyst / chlorophyll absorbs light [1]
carbon dioxide and water react [1]
to make glucose / carbohydrates / starch / sugar / named sugar [1]

[Total: 13]

PhysicsAndMathsTutor.com
5 (a) (making) fertilisers / nitric acid / nylon / refrigeration / explosives / cleaning products; [1]

(b) alkane / named alkane; [1]

water / steam; [1]
heat / catalyst; [1]

or electrolysis; [1]
suggest suitable electrolyte; (allow: water) [1]
hydrogen at cathode; [1]

or cracking; [1]
alkane / named alkane; [1]
heat or catalyst [1]

(c) any five from:

faster; (rate) [1]

more collisions / molecules closer together / more particles per unit volume; [1]

(collisions) more frequent / more often / more chance / more effective or successful
collisions / more collisions with Ea / increase rate of collisions; [1]

higher yield / moves (equilibrium) to RHS / more ammonia / to side of products / high
pressure favours the reaction with less moles; [1]

less moles / molecules / volume on RHS ORA (can be implied in previous

comments) [1]

high pressure means lower temperature can be used to achieve comparable rate
(thus saving energy); [1]

6 (d) (i) endothermic takes in / absorbs / uses / needs / gains energy / heat and
exothermic gives out / loses energy / heat; [1]

(ii) 2328 (ignore + or – ) / 6 × 388 (not evaluated); [1]

944 + 1308 / 2252 and endothermic and exothermic in table; [1]

2328>2252 or (–) 76 kJ; [1]

or energy of products / RHS > reactants / LHS

or energy needed to break bonds < energy given out on formation of bonds.
[Total: 13]

PhysicsAndMathsTutor.com
1 Fertilisers are used to promote plant growth.
Two fertilisers are ammonium phosphate, (NH4)3PO4, and calcium dihydrogenphosphate,
Ca(H2PO4)2.

(a) Describe a test to distinguish between these two fertilisers.

test ....................................................................................................................................

..................................................................................................................................... [2]

result .................................................................................................................................

..................................................................................................................................... [1]

(b) Many fertilisers are manufactured from ammonia. Describe how ammonia is made in the
Haber process. Give the essential conditions and an equation for the process.

...........................................................................................................................................

..................................................................................................................................... [4]

..................................................................................................................................... [1]

(d) The soluble compound, calcium dihydrogenphosphate is made by heating the insoluble
mineral rock phosphate, Ca3(PO4)2, with sulfuric acid.

(i) Why would rock phosphate not be effective as a fertiliser?

.............................................................................................................................. [1]

(ii) The phosphate ion, PO43–, from the rock phosphate is changed into the
dihydrogenphosphate ion, H2PO4–.

PO43– + 2H2SO4 → H2PO4– + 2HSO4–

What type of reagent is the phosphate ion? Give a reason for your choice.

....................................................................................................................................

.............................................................................................................................. [2]

(e) The extensive use of fertilisers and possibly the effect of acid rain tend to increase the
acidity of the soil. State why it is necessary to control soil acidity and explain how this can
be done.

...........................................................................................................................................

..................................................................................................................................... [2]

[Total: 13]
PhysicsAndMathsTutor.com
2 Ammonia is an important industrial chemical.

(a) (i) Give the electron structure of an atom of nitrogen.

.............................................................................................................................. [1]

(ii) Use this electronic structure, rather than the valency of nitrogen, to explain why the
formula of ammonia is NH3 not NH4.

....................................................................................................................................

.............................................................................................................................. [2]

(b) Ammonia is made by the Haber Process.

N2(g) + 3H2(g) 2NH3(g) forward reaction is exothermic

The percentage of ammonia in the equilibrium mixture varies with conditions.

pressure / atmospheres 100 200 300 400

% ammonia at 300 °C 45 65 72 78
% ammonia at 500 °C 9 18 25 31

The conditions actually used are 200 atmospheres, 450 °C and an iron catalyst.

(i) The original catalyst was platinum. Suggest a reason why it was changed to iron.

.............................................................................................................................. [1]

(ii) Explain why the highest pressure gives the highest percentage of ammonia in the
equilibrium mixture.

....................................................................................................................................

.............................................................................................................................. [2]

(iii) What happens to the unreacted nitrogen and hydrogen?

....................................................................................................................................

.............................................................................................................................. [1]

PhysicsAndMathsTutor.com
(iv) State one advantage and one disadvantage of using a lower temperature.

advantage .................................................................................................................

.............................................................................................................................. [1]

disadvantage ............................................................................................................

.............................................................................................................................. [1]

[Total: 9]

PhysicsAndMathsTutor.com
3 Ammonia is manufactured by the Haber process.

N2(g) + 3H2(g) 2NH3(g) the forward reaction is exothermic

(a)
a) Name the raw materials from which nitrogen and hydrogen are obtained.

nitrogen from [1]

hydrogen from [1]

(ii) Name the catalyst used in this process.

[1]

(iii) What is the most important use of ammonia?

[1]

(b) The following graph shows how the percentage of ammonia in the equilibrium mixture
changes with temperature.

% ammonia
at equilibrium

0
0 temperature

(i) Explain the term equilibrium.

[2]

(ii) How does the percentage of ammonia vary with temperature?

[1]

PhysicsAndMathsTutor.com
(c) (i) Sketch a graph which shows how the percentage of ammonia in the equilibrium
mixture varies with pressure.

% ammonia
at equilibrium

0
0 pressure

[1]

(ii) Explain why the graph has the shape shown.

[2]

[Total: 10]

PhysicsAndMathsTutor.com
4 Ammonia is manufactured by the Haber Process.

N2(g) + 3H2(g) 2NH3(g)

200 atmospheres
450°C

The forward reaction is exothermic.

(a) (i) What is the catalyst for this reaction?

[1]

(ii) Newer catalysts have been discovered for this process. Using these catalysts, the
operating temperature is lowered from 450°C to 400°C. What is the advantage of
using a lower temperature?
Explain your answer.

advantage

explanation

[2]

(b) After passing over the catalyst, the mixture contains 15% of ammonia. It is cooled and
the ammonia liquefies and is separated from the unreacted nitrogen and hydrogen.
They are recycled.

(i) How are the gases recycled?

[1]

(ii) Only ammonia gas liquefies. Suggest an explanation for this.

[1]

(c) Urea, CO(NH2)2, is one of the fertilisers manufactured from ammonia.

Ammonia is heated with carbon dioxide.

(i) Write an equation for the manufacture of urea.

[2]

(ii) Explain why urea on its own might not be very effective in promoting crop growth.

[1]

PhysicsAndMathsTutor.com
(d) Give a diagram showing the arrangement of the valency electrons in one molecule of
the covalent compound urea. Its structural formula is given below.

H
N
H
O C
H
N
H

Use ο to represent an electron from a carbon atom.

Use x to represent an electron from a hydrogen atom.
Use • to represent an electron from a nitrogen atom.

[3]

PhysicsAndMathsTutor.com
13

5 In 1909, Haber discovered that nitrogen and hydrogen would react to form ammonia. The
yield of ammonia was 8%.

N2 (g) + 3H2 (g) 2NH3 (g) the forward reaction is exother

catalyst platinum
temperature 600 oC
pressure 200 atm

(a) Describe how hydrogen is obtained for the modern process.

[2]

(b)
b) What is the catalyst in the modern process?

[1]

(ii) Explain why the modern process, which uses a lower temperature, has a higher
yield of 15%.

[2]

(c)
c) Complete the following table that describes the bond breaking and forming in the
reaction between nitrogen and hydrogen to form ammonia.

energy change
bonds exothermic or endothermic
/kJ

1 mole of N N
+94
broken

3 moles of +130
broken

6 moles of N – H
-232
formed
[3]

(ii) Explain, using the above data, why the forward reaction is exothermic.

[2]

PhysicsAndMathsTutor.com
6 An organic compound decomposes to form nitrogen.

C6H5N2Cl(aq) → C6H5Cl(l) + 2(g)

(a) Explain the state symbols.

g [2]

(b) Draw a diagram to show the arrangement of the valency electrons in one molecule of
nitrogen.

[2]

PhysicsAndMathsTutor.com
(c) The rate of this reaction can be measured using the following apparatus.

20 40 60 80 100 cm3

nitrogen gas

solution of
organic compound

The results of this experiment are shown on the graph below.

volume of
nitrogen

0
0 time

(i) How does the rate of this reaction vary with time?

[1]

(ii) Why does the rate vary?

[2]

(iii) The reaction is catalysed by copper powder. Sketch the graph for the catalysed
reaction on the same grid. [2]

(iv) Why is copper powder more effective as a catalyst than a single piece of copper?

[1]

PhysicsAndMathsTutor.com
1 (a sodium hydroxide solution [1]
warm [1]
(only) ammonium phosphate gives off ammonia / gas (which will turn red litmus paper
blue) [1]
or:
sodium hydroxide solution [1]
dissolve fertiliser in water [1]
Ca2+ gives (white) ppt [1]
or:
flame test [1]
Ca2+ brick red / orange / orange-red [1]
NH4+ no colour [1]

(b) iron catalyst [1]

pressure 150–300 atmospheres [1]
temperature 370–470 °C [1]
N2 + 3H2 ⇌ 2NH3 [1]
note: units required for temperature and pressure

(c) potassium / K [1]

(d)
d) ( needs to be soluble / in solution (to be absorbed by plants) [1]

(ii) base [1]

proton acceptor [1]

(e) plant growth depends on soil acidity or pH / plants have optimum pH (for growth) [1]

add Ca(OH)2 / CaO / CaCO3 / lime / slaked lime / quicklime / limestone [1]

2 (a (i) nitrogen 2+5 [1]

(ii) needs three electrons [1]

to complete energy level [1]

(b)
b) expensive metal / iron cheaper / better catalyst [1]

(ii) high pressure favours side with smaller volume / fewer moles [1]
this is right hand side / product / ammonia side [1]

(iii) recycled / sent over catalyst again [1]

accept used again

(iv) advantage high yield [1]

disadvantage slow reaction rate etc [1]

[Total: 9]

PhysicsAndMathsTutor.com
3 (a (i) air (liquid) [1]
petroleum or crude oil or alkanes or methane or water or steam or steam reforming or
suitable aqueous solution e.g. brine or sea water [1]
NOTE: cannot crack methane

(ii) iron [1]

(iii) (as a) fertiliser or to make fertilisers or to make nitric acid [1]

(b) (i) concentrations/macroscopic properties do not change [1]

accept amounts stay the same
NOT no change

rate of forward and back reactions equal [1]

(ii) it decreases with increase temperature [1]

or it increases with decrease temperature

(c) (i) shows an increase either a line or curve [1]

(any decrease = 0)

(ii) increase pressure favours the side with lower volume or molecules or moles [1]
that is RHS or products side [1]
ignore any mention of rates

[Total: 10]

4 (a) (i) iron [1]

(ii) advantage higher yield [1]

explanation lower temperature favours the exothermic reaction
(that is the forward reaction) [1]

(b) (i) Sent over the catalyst again or used to make more ammonia [1]
NOT just reused

(ii) It has the highest boiling point [1]

(c) (i) CO2 + 2NH3 = CO(NH2)2 + H2O [2]

Not balanced [1]

(ii) Any comment based on deficiency of PK/or ONLY provides Nitrogen as a

nutrient [1]
NOT soil pH

(d) Correct diagram for urea [3]

one error ONLY [2]
two errors ONLY [1]
three errors 0

[TOTAL = 11]

PhysicsAndMathsTutor.com
5 (a) from methane [1]
and water [1]

OR electrolysis [1]
suitable electrolyte [1]

OR alkane [1]
cracking [1] [2]

(b)(i) iron [1]

(ii) lower temperature moves equilibrium to right [1]

because forward reaction is exothermic [1]

(c)(i) H—H [1]

endothermic [1]
endothermic [1]
exothermic

(ii) More heat given out than taken in [1]

–2328 + 945 + 1308 = –75(kJ) [1]

OR More heat given out bond forming than taken in bond breaking [2]
Must mention bond breaking and forming [2]

TOTAL = 10

6 (a) dissolved or solution in water [1]

NOT aqueous NOT soluble in water
l liquid and g gas [1]

(b) 6 electrons in bond between two nitrogen atoms [1]

2 electrons on each nitrogen [1]
ignore any coding of electrons with dots or crosses

(ii) concentration or number of effective collisions [1]

decreases [1]
used up or less chemical or less collisions etc [1] only

(iii) greater initial slope [1]

same final point [1]
as long as new curve touches the original curve near
the top allocate the mark

(iv) greater surface area [1]

TOTAL = [10]

PhysicsAndMathsTutor.com
1 Ammonia contains the elements nitrogen and hydrogen. It is manufactured from these elements
in the Haber process.

N2(g) + 3H2(g) 3(g)

The forward reaction is exothermic.

(a) (i) Nitrogen is obtained from liquid air by fractional distillation. Why does this technique
separate liquid oxygen and nitrogen?

...................................................................................................................................

(ii) Name two raw materials from which hydrogen is manufactured.

...............................................................................................................................[3]

(b) The table shows how the percentage of ammonia in the equilibrium mixture varies with
pressure at 600 °C.

percentage ammonia 8 12 15 20

pressure/atm 200 300 400 500

(i) Explain why the percentage of ammonia increases as the pressure increases.

...................................................................................................................................

...............................................................................................................................[2]

(ii) How would the percentage of ammonia change if the measurements had been made
at a lower temperature?
Explain your answer.

...................................................................................................................................

...............................................................................................................................[2]

(iii) State two of the reaction conditions used in the Haber Process.

...................................................................................................................................

...............................................................................................................................[2]

PhysicsAndMathsTutor.com
(c) Ammonia is a base.

(i) Name a particle that an ammonia molecule can accept from an acid.

...................................................................................................................................

(ii) Write an equation for ammonia acting as a base.

...............................................................................................................................[3]

(d) Given aqueous solutions, 0.1mol/dm3, of sodium hydroxide and ammonia, describe how
you could show that ammonia is the weaker base.

..........................................................................................................................................

......................................................................................................................................[2]

(e) Another compound that contains nitrogen and hydrogen is hydrazine, N2H4.

(i) Draw the structural formula of hydrazine. Hydrogen can form only one bond per
atom but nitrogen can form three.

(ii) Draw a diagram that shows the arrangement of the valency electrons in one
molecule of hydrazine. Hydrazine is a covalent compound.
Use x to represent an electron from a nitrogen atom.
Use o to represent an electron from a hydrogen atom.

[3]

PhysicsAndMathsTutor.com
2 This question is about compounds of nitrogen.

(a) (i) Describe the Haber Process giving reaction conditions and a chemical equation.
Reference to rate and yield is not required.

.............................................................................................................................................

....................................................................................................................................... [5]

(ii) Give one use of ammonia.

....................................................................................................................................... [1]

(b) The diagram shows the structure of a hydrazine molecule.

H H

N N

H H

Draw the electron arrangement of a hydrazine molecule. Show the outer shell electrons only.

[2]

(c) Hydrazine is a base.

(i) base.

....................................................................................................................................... [1]

(ii) Complete the chemical equation to show that hydrazine acts as a base when added to
water.

N2H4 + H2O → .............. + .............. [1]

PhysicsAndMathsTutor.com
(d) Nitrogen dioxide is an atmospheric pollutant.

(i) State one environmental problem caused by nitrogen dioxide.

....................................................................................................................................... [1]

(ii) Explain how oxides of nitrogen, such as nitrogen dioxide, are formed in car engines.

.............................................................................................................................................

....................................................................................................................................... [2]

[Total: 13]

PhysicsAndMathsTutor.com
3 The Atacama desert in Chile has deposits of the salt sodium nitrate. Very large amounts of this
salt were exported to Europe for use as a fertiliser. After the introduction of the Haber process in
1913, this trade rapidly diminished.

(a) (i) Explain why the introduction of the Haber process reduced the demand for
sodium nitrate.

.............................................................................................................................................

....................................................................................................................................... [2]

(ii) Suggest why surface deposits of sodium nitrate only occur in areas with very low rainfall
such as desert areas.

....................................................................................................................................... [1]

(iii) The desert has smaller surface deposits of potassium nitrate.

Suggest why potassium nitrate is a better fertiliser than the sodium salt.

....................................................................................................................................... [1]

(b) All nitrates decompose when heated. The extent to which a nitrate decomposes is
determined by the metal in the salt.

(i) Sodium nitrate decomposes to form sodium nitrite, NaNO2.

Write the equation for decomposition of sodium nitrate.

....................................................................................................................................... [2]

(ii) Sodium nitrite is a reducing agent.

What would be observed if an excess of sodium nitrite solution was added to a solution
of acidified potassium manganate(VII)?

....................................................................................................................................... [2]

(iii) Copper(II) nitrate decomposes to form copper(II) oxide, nitrogen dioxide and oxygen.

What is the relationship between the extent of decomposition and the reactivity of the
metal in the nitrate?

.............................................................................................................................................

....................................................................................................................................... [1]

PhysicsAndMathsTutor.com
(c) The equation for the decomposition of copper(II) nitrate is given below.

2Cu(NO3)2 → 2CuO + 4NO2 + O2

(i) Predict what you would observe when copper(II) nitrate is heated.

.............................................................................................................................................

....................................................................................................................................... [3]

(ii) Copper(II) nitrate forms a series of hydrates with the formula Cu(NO3)2.xH2O.
All these hydrates decompose to form copper(II) oxide.
1 mole of Cu(NO3)2.xH2O forms 1 mole of CuO.

What is meant by 1 mole of a substance?

.............................................................................................................................................

....................................................................................................................................... [2]

(iii) 7.26 g of a hydrate, Cu(NO3)2.xH2O, formed 2.4 g copper(II) oxide.

number of moles of CuO formed = ......................

number of moles of Cu(NO3)2.xH2O in 7.26 g = ......................

mass of 1 mole of Cu(NO3)2.xH2O = ...................... g

mass of 1 mole of Cu(NO3)2 is 188 g

the value of x in this hydrate = ......................

[4]

[Total: 18]

PhysicsAndMathsTutor.com
1 (a) (i) different boiling points [l]
(ii) methane or water or petroleum or named petroleum
fraction or alkane
Any T\VO [2]

( b) (i) volume decrease for forward reaction or fewer moles

of gas on products side [1]
favoured by increase in pressure [ 1]
or increase in pressure moves position of equilibrium to right
(ii) increase [1]
exothermic reaction favoured by lower temperature [l]

(iii) 300 to 600 QC

1 :3 volume ratio
iron (catalyst)
150 to 300 atm
AnyT\VO [2]

(c) (i) proton [2]

,_
hydrogen ion or H ONLY [1]
(ii) correct equation molecular or ionic [1]
NH3 + HCI = NH4CJ
NH3 + H' = NHt accept NH.OH

(d) measure pH or add universal indicator or pH meter [1]

ammonia has lower pH if numerical values given

must be appropriate that is above 7 with ammonia having the lower

value or correct colours, green and blue are acceptable [1]
OR measure conductivity [1]
ammonia has poorer conductivity [1]

(e) (i) correct structural formula [l]

H H
"N-N I
H
/ " H
(ii) 8e around nitrogen [1]
2e around each hydrogen [1]

H H
')CO
H .,c N H
0
�'I.

TOTAL = 17

PhysicsAndMathsTutor.com
Question Answer Marks

2(a)(i) pressure in range 150–300 atmospheres / atm; 5

temperature in range 370–470 °C;
iron (catalyst);
balanced equation: N2 + 3H2 → 2NH3;
equilibrium / reversible;
(a)(ii) manufacture of fertilisers / nylon / nitric acid / cleaning agent(allow oven cleaner) / hair dye / urea / refrigeration / explosives; 1
(b) 2

H H
N N
H H
M1 all shared electrons correct (5 bonds);
M2 exactly two non-bonding electrons on each N and no additional non-bonding electrons;
(c)(i) / H+ acceptor; 1
+
(c)(ii) 2H4 + H2O) → N2H5 + OH ; 1
or
(N2H4) + 2H2O → N2H62+ + 2OH ;
(d)(i) rain / effect of acid rain / (photochemical) smog / (producing) low level ozone; 1
(d)(ii) M1 nitrogen and oxygen (from the air) react / combine or word equation; 2
M2 at high temperature / spark / very hot;

PhysicsAndMathsTutor.com
Question Answer Marks Guidance

3(a)(i) (Haber process makes) ammonia / NH3 ;

(ammonia converted into) fertilisers / nitrates / ammonium salts or names or A 2 marks for ‘ammonia is a fertiliser’
formulae of examples e.g. ammonium nitrate / NH4NO3 / ammonium sulfate / A ammonia is used to make sodium nitrate
(NH4)2SO4 / calcium nitrate / Ca(NO3)2 / urea / CO(NH2)2 ; 2 Haber process used to make fertilisers gets
second mark only
(a)(ii) it (refers to sodium nitrate) / sodium nitrate would dissolve (in rain) / soluble (in A reacts with water
water) / wash away / leach / drain off; 1 I reference to fertiliser
R sodium reacts / dissolves
A because they are not dissolved by rainfall
(implication is in desert)
(a)(iii) potassium (is required by plants as well as nitrogen) / NPK; 1 comments about pH / better for soil / %N
higher / reactivity of potassium
I comments about what K does for plants e.g.
combat disease
(b)(i) 3 → 2NaNO2 + O2
species; A multiples
balancing; 2 I state symbols / word equation

PhysicsAndMathsTutor.com
Question Answer Marks Guidance

3(b)(ii) (colour changes) from pink / purple;

to colourless / decolourised; 2 I clear / discoloured / effervescence
I brown fumes / brown gas
NOTE: stays pink or purple gets first mark but
turns purple or pink is 0
(b)(iii) the more reactive the metal the lower rate of decomposition / more difficult the A less (extent the) decomposition
decomposition / more stable the nitrate / more energy needed to decompose / A reactive metals produce nitrates difficult to
decomposes at higher temperature ora; 1 decompose ora i.e. comparatives not essential
A the more reactive the metal the less it
decomposes is acceptable because we can
assume that it refers to the nitrate BOD
A inverse relationship with further qualification
A group 1 / reactive metals produce nitrite (and
oxygen) and less reactive metals produce
oxide (+ NO2 + O2) (both required for mark)
I less products (unqualified)
R less products / metals decompose
3(c)(i) (changes from) blue solid / blue crystals; R precipitate
black solid formed; A one mark out of the first two for changes
from blue to black (without solid or crystals)

brown gas / brown vapour / (pungent) smell; 3 I red / melt

I water / steam / condensation given off
I reference to glowing / burning splints /
colourless gas / effervescence
I names / formulae

PhysicsAndMathsTutor.com
Question Answer Marks Guidance

3(c)(ii) Avogadro(’s) number / constant / 6.02 × 1023; COND particles; A any values from 6 to 6.023 ×1023
A atoms / ions / molecules / electrons
OR
(the number of particles which is equal to the number of atoms in) 12 g of A one mark for reference to C12
carbon 12; COND atoms; A equivalent statement for any element or
compound e.g. 32 grams of oxygen(1) COND
OR molecules / O2 (1) e.g. 16 grams of oxygen (1)
the mass in grams which contains Avogadro(’s) Number; COND particles; COND atoms / O(1)

OR
(the amount of substance which has a mass equal to) its relative formula
mass / RFM / relative atomic mass / Ar / relative molecular mass / Mr / molar
mass; COND in grams;

OR A different volumes under different conditions

(the amount of substance which has a volume equal to) 24 dm3; COND of a e.g. 22.4 dm3 at STP or volumes in different
gas at RTP; 2 units e.g. 24 000 cm3 at RTP
(c)(iii)
(number of moles of CuO formed = ) 0.03;

M2
(number of moles of Cu(NO3)2.xH2O in 7.26 g = ) 0.03; ecf same as M1

M3
(mass of 1 mole of Cu(NO3)2.xH2O 7.26 ÷ 0.03 =) 242 (g); ecf 7.26 ÷ M2
(mass of 1 mole of Cu(NO3)2 is 188 g)

M4
the value of x = 3; 4 ecf M3 – 188 ÷ 18

PhysicsAndMathsTutor.com
1 Ammonia is manufactured by the Haber process. Nitrogen and hydrogen are passed over a catalyst
at a temperature of 450 °C and a pressure of 200 atmospheres.

The equation for the reaction is as follows.

N2 + 3H2 2NH3

The forward reaction is exothermic.

(a) State one use of ammonia.

.............................................................................................................................................. [1]

(b) What is the meaning of the symbol ?

.............................................................................................................................................. [1]

nitrogen ......................................................................................................................................

hydrogen ....................................................................................................................................
[2]

(d) Name the catalyst in the Haber process.

.............................................................................................................................................. [1]

(e)
e) If a temperature higher than 450 °C was used in the Haber process, what would happen to
the rate of the reaction? Give a reason for your answer.

.............................................................................................................................................

....................................................................................................................................... [2]

(ii) If a temperature higher than 450 °C was used in the Haber process, what would happen to
the yield of ammonia? Give a reason for your answer.

.............................................................................................................................................

....................................................................................................................................... [2]

PhysicsAndMathsTutor.com
(f)
f) If a pressur ocess, what would
happen to the yield of ammonia? Give a reason for your answer.

.............................................................................................................................................

....................................................................................................................................... [2]

(ii) Explain why the rate of reaction would be faster if the pressure was greater than
200 atmospheres.

.............................................................................................................................................

....................................................................................................................................... [1]

(iii) Suggest one reason why a pressure higher than 200 atmospheres is not used in the
Haber process.

.............................................................................................................................................

....................................................................................................................................... [1]

(g) Draw a dot-and-cross diagram to show the arrangement of the outer (valency) electrons in one
molecule of ammonia.

[2]

(h) Ammonia acts as a base when it reacts with sulfuric acid.

(i) What is a base?

....................................................................................................................................... [1]

(ii) Write a balanced equation for the reaction between ammonia and sulfuric acid.

....................................................................................................................................... [2]

[Total: 18]
PhysicsAndMathsTutor.com
2 Ammonia is made by the Haber process.

N2(g) + 3H2(g) 2NH3(g)

The forward reaction is exothermic.

The conditions in the reaction chamber are:

● a pressure of 200 atmospheres,

● a catalyst of finely divided iron,
● a temperature of 400 to 450 °C.

(a) What are the two advantages of using a high pressure? Give a reason for both.

advantage 1 ...............................................................................................................................

reason ........................................................................................................................................

....................................................................................................................................................

advantage 2 ...............................................................................................................................

reason ........................................................................................................................................

....................................................................................................................................................
[4]

(b) A higher temperature would give a faster reaction rate.

Why is a higher temperature not used?

....................................................................................................................................................

.............................................................................................................................................. [3]

.............................................................................................................................................

....................................................................................................................................... [1]

(ii) Give two reasons why a catalyst is used.

.............................................................................................................................................

....................................................................................................................................... [2]

PhysicsAndMathsTutor.com
(d) The equilibrium mixture leaving the reaction chamber contains 15% ammonia. Suggest how
the ammonia could be separated from the mixture.

boiling point / °C
hydrogen –253
nitrogen –196
ammonia –33

....................................................................................................................................................

.............................................................................................................................................. [2]

(e) Ammonia is used to make nitrogen trifluoride, NF3.

Nitrogen trifluoride is essential to the electronics industry. It is made by the following reaction.

F F H F
H N H + F F → F N F + H F
F F H F
H F

Determine if the above reaction is exothermic or endothermic using the following bond energies
and by completing the following table. The first line has been done as an example.
Bond energy is the amount of energy, in kJ / mole, needed to break or make one mole of the
bond.

bond bond energy in kJ / mole

N–H 390
F–F 155
N–F 280
H–F 565

bond energy change / kJ

N–H (3 × 390) = 1170
F–F
N–F
H–F

....................................................................................................................................................

.............................................................................................................................................. [4]

[Total: 16]

PhysicsAndMathsTutor.com
3 All metal nitrates decompose when heated. A few form a nitrite and oxygen. Most form the

metal oxide, oxygen and a brown gas called nitrogen dioxide.

(a) (i) Name a metal whose nitrate decomposes to form the metal nitrite and oxygen.

.............................................................................................................................. [1]

(ii) Complete the equation for the action of heat on lead(II) nitrate.

......Pb(NO3)2 → ......... + ......NO2 + O2 [2]

(iii) Suggest why the nitrate of the metal, named in (a)(i), decomposes less readily than
lead(II) nitrate.

....................................................................................................................................

.............................................................................................................................. [2]

PhysicsAndMathsTutor.com
(b) Almost all samples of nitrogen dioxide are an equilibrium mixture of nitrogen dioxide,
NO2, and dinitrogen tetroxide, N2O4.

forward reaction
2NO2(g) N2O4(g)
reverse reaction
dark brown colourless

In the forward reaction, a bond forms between the two nitrogen dioxide molecules.

NO2 + NO2 → O2N – NO2

(i) Explain the term equilibrium mixture.

....................................................................................................................................

.............................................................................................................................. [1]

(ii) The syringe contains a sample of the equilibrium mixture. The plunger was pulled
back reducing the pressure.
How would the colour of the gas inside the syringe change? Give an explanation for
your answer.

equilibrium mixture

sealed end

gas syringe

....................................................................................................................................

.............................................................................................................................. [3]

(iii) A sealed tube containing an equilibrium mixture of nitrogen dioxide and dinitrogen
tetroxide was placed in a beaker of ice cold water.
The colour of the mixture changed from brown to pale yellow.

Is the forward reaction exothermic or endothermic? Give an explanation for your

choice.

....................................................................................................................................

.............................................................................................................................. [2]

(iv) What other piece of information given in the equation supports your answer to (iii)?

NO2 + NO2 → O2N–NO2

.............................................................................................................................. [1]

[Total: 12]
PhysicsAndMathsTutor.com
4 Nitrogen dioxide is a brown gas. It can be made by heating certain metal nitrates.

2Pb(NO3)2 → 2PbO + 4NO2 + O2

(a)
a) Name another metal whose nitrate decomposes to give the metal oxide, nitrogen
dioxide and oxygen.

.............................................................................................................................. [1]

(ii) Complete the word equation for a metal whose nitrate does not give nitrogen dioxide
on decomposition.

metal nitrate → ..................................................... + oxygen

[1]

(b) At most temperatures, samples of nitrogen dioxide are equilibrium mixtures.

2NO2(g) N2O4(g)
dark brown pale yellow

(i) At 25 °C, the mixture contains 20 % of nitrogen dioxide. At 100 °C this has risen to
90 %. Is the forward reaction exothermic or endothermic?
Give a reason for your choice.

....................................................................................................................................

.............................................................................................................................. [2]

(ii) Explain why the colour of the equilibrium mixture becomes lighter when the pressure
on the mixture is increased.

....................................................................................................................................

.............................................................................................................................. [2]

PhysicsAndMathsTutor.com
(c) A 5.00 g sample of impure lead(II) nitrate was heated. The volume of oxygen formed was
0.16 dm3 measured at r.t.p. The impurities did not decompose.
Calculate the percentage of lead(II) nitrate in the sample.

2Pb(NO3)2 → 2PbO + 4NO2 + O2

Number of moles of O2 formed = .......................................

Number of moles of Pb(NO3)2 in the sample = .......................................

Mass of one mole of Pb(NO3)2 = 331 g

Mass of lead(II) nitrate in the sample = ....................................... g

Percentage of lead(II) nitrate in sample = ..................................... [4]

[Total: 10]

PhysicsAndMathsTutor.com
1 (a (making) fertilisers / nitric acid / nylon / explosives / urea
(for) cleaning products (allow oven cleaner) / refrigeration
efr

eve
(b) equilibrium / reversible

(c) (nitrogen)air / atmosphere [1]

(hydrogen) methane / water / steam / alkane / named alkane / hydrocarbon / crude oil
or petroleum / natural gas [1]

(d) iron [1]

ast
(e) (i) rate increases / faster

More (effective) collisions [1]

(ii) yield decreases [1]

(forward reaction) exothermic / reverse reaction endothermic / high temp

favours endothermic reaction [1]

(f) (i) yield increases [1]

less / fewer molecules or moles or volume on RHS ORA / high pressure

favours reaction which produces fewer molecules or moles or volume [1]

(ii) particles / molecules closer / more particles per unit area or volume / more
molecules per unit area or volume / more concentration / particles have less
space between them and more collisions [1]

(iii) safety issues / higher cost [1]

(g) 3 bond pairs between N & H [1]

Lone pair on N [1]

(h)
h) ( proton / H+ acceptor
cce

(ii) 2NH3 + H2SO4 → (NH4)2SO4 [2]

Formula of (NH4)2SO4 (1)

The rest (1)

[Total:18]

PhysicsAndMathsTutor.com
2 (a faster reaction rate (1)
higher collision rate (1)
greater yield or favour RHS (1)
pressure favours products because it has lower volume / fewer product molecules (1) [4]

(b) higher temperature favour endothermic reaction (1)

this is the back reaction / left hand side / reactants (1)
reduce yield (1) [3]

(ii) increase reaction rate (1)

can use a lower temperature to have an economic rate (1)
and not decrease yield (by increasing temperature). [2]

(d) lower the temperature (1)

only ammonia will liquefy (1)
OR
add water (1)
only ammonia will dissolve (1)
OR
increase pressure (1)
only ammonia will liquefy (1) [2]

(e) second line +3 × 155 = + 465

third line –3 × 280 = (–)840
fourth line –3 × 565 = (–)1695
all three correct (2)
two correct (1)

1170 + 465 = 1635

840 + 1695 = 2535
both numerically correct (1)
exothermic reaction with some reasoning (1) [4]

[Total: 16]

PhysicsAndMathsTutor.com
3 (a (i) any Group 1 metal [1]
ACCEPT: lithium

(ii) 2Pb(NO3)2 → 2PbO + 4NO2 + O2 [2]

PbO [1]
COND balancing [1]

(iii) the metal in a (i) is more reactive than lead [1]

more reactive metals have more stable compounds
OR has stronger (ionic) bonding [1]

(b) (i) speed / rate of forward reaction = speed / rate of back reaction [1]
OR macroscopic properties do not change / constant (with time)

(ii) goes darker OR goes brown [1]

COND lower pressure favours side with more moles [1]
COND this is NO2 side OR reactant side OR goes left [1]

(iii) exothermic [1]

low temperatures favour the exothermic reaction or

low temperatures moves equilibrium to right / product side / towards N2O4 [1]

(iv) forward reaction is bond forming [1]

PhysicsAndMathsTutor.com
4 (a (i) accept all metals excluding Group I (lithium is acceptable) [1]
not lead accept silver

(ii) M nitrite / nitrate(III) [1

not nitride

(b) (i) exothermic [1]

not reverse reaction is endothermic as the question asks about the forward reaction
cond forward reaction favoured by low temperature / reverse reaction favoured by
high temperature [1]
second mark only scores if exothermic is correct.

(ii) position of equilibrium to right / forwards / more products / more N2O4 / lighter colour [1]
because this side has smaller volume / fewer moles [1]

(c) if the final answer is between 86–89% award all 4

if the final answer is between 66–67% award 3 marks (Mr of 32 must have been used)
for all other answers marks can be awarded using the mark scheme as below and applying
ecf if necessary

number of moles of O2 formed = 0.16/24 = 0.0067/0.00667 or 1/150

number of moles of Pb(NO3)2 in the sample = 0.0133/0.013 or 1/75
mass of one mole of Pb(NO3)2 = 331 g
mass of lead(II) nitrate in the sample = 4.4(1) g
percentage of lead(II) nitrate in sample = 88.3% (allow 88–89) [4]

mark ecf in this question but not to simple integers

if mass of lead(II) nitrate > 5.00 only marks 1 and 2 available
If divides by 32 (not 24) only last 3 marks can score consequentially

PhysicsAndMathsTutor.com
1 The diagram shows some of the processes which determine the percentage of carbon dioxide
in the atmosphere.

carbon dioxide
in atmosphere

combustion respiration photosynthesis

(a) Explain how the following two processes alter the percentage of carbon dioxide in the
atmosphere.

(i) combustion

....................................................................................................................................

.............................................................................................................................. [3]

PhysicsAndMathsTutor.com
(ii) respiration

....................................................................................................................................

.............................................................................................................................. [3]

(b) Photosynthesis reduces the percentage of carbon dioxide in the atmosphere.

(i) Complete the word equation for photosynthesis.

carbon dioxide + water → ........................ + ........................ [2]

(ii) State two essential conditions for the above reaction to occur.

....................................................................................................................................

.............................................................................................................................. [2]

[Total: 10]

PhysicsAndMathsTutor.com
2 Two important greenhouse gases are methane and carbon dioxide.

(a) Methane is twenty times more effective as a greenhouse gas than carbon dioxide. The
methane in the atmosphere comes from both natural and industrial sources.

(i) Describe two natural sources of methane.

....................................................................................................................................

.............................................................................................................................. [2]

(ii) Although methane can persist in the atmosphere for up to 15 years, it is eventually
removed by oxidation.
What are the products of this oxidation?

.............................................................................................................................. [2]

(b) How do the processes of respiration, combustion and photosynthesis determine the
percentage of carbon dioxide in the atmosphere?

...........................................................................................................................................

..................................................................................................................................... [4]

[Total: 8]

PhysicsAndMathsTutor.com
3 The diagram shows part of the carbon cycle. This includes some of the processes which
determine the percentage of carbon dioxide in the atmosphere.