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Key points of Chemistry 5070

Kamal Ahmed Ansari

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Kamal Ahmed Ansari

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Acid-Base Indicators
Indicators Neutral Acid Base

Universal Green Red Blue/Purple

Litmus Yellow Red Blue
Methyl Orange Orange Red Yellow
thymolphthalein Colorless Colorless Blue

Redox Agents

Change of Colors
Potassium dichromate (VI) Orange to green
Potassium manganate (VII) Purple to colorless
Potassium Iodide Colorless to brown

Test Of Gases

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Collection of gases:
The table below shows the density and solubility of various common gases.
Gas Colour Density Solubility
(compare to air) (in water)
Ammonia Colourless Lighter Extremely soluble
Carbon dioxide Colourless Heavier Slightly soluble
Chlorine Green/yellow Much heavier Soluble
Hydrogen Colourless Much lighter Insoluble
Hydrogen chloride Colourless Slightly heavier Very soluble
oxygen Colourless About the same Slightly soluble
Note
1. Gases which are lighter than air (hydrogen, ammonia) can be collected by upward delivery or downward
displacement of air.
2. Gases which are heavier than air (carbon dioxide, chlorine) can be collected by downward delivery or
upward displacement of air.

Gases are insoluble in water collected over the water like Oxygen

Purification:

Method of purification Applications

Filtration Separating soluble and insoluble solid
Evaporation Separating a soluble solid
Crystallization Separating a solid either cooling or its
molten solution
Simple distillation Separating liquid from a solution
Fractional distillation Separating a mixture of miscible liquid
Sublimation Separating ammonia and iodine salt
chromatography Separating color, dyes and amino acid

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Solubility of salts

Test Of Cat ions

Ions NaOH few drops NaOH NH4OH few drops NH4OH excess
excess
Ca+2 White ppts Insoluble No reaction No reaction
Al+3 White ppts Dissolve White ppts Insoluble
Zn+2 White ppts Dissolve White ppts Dissolve
Fe+2 Dirty green ppts Insoluble Dirty green ppts Insoluble
Fe+3 Red-Brown ppts Insoluble Red-Brown ppts Insoluble
Cu+2 Blue ppts Insoluble Blue ppts Dissolve (deep blue
solution)
NH4 +1 Damp red litmus paper turns blue No reaction No reaction
and ammonia gas is released.

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Test Of An ions

Anion Test What happens is anion is

present?
Carbonate Add dilute hydrochloric acid Anion is present if bubbles
give off gas that turns
limewater milky
Chloride Add dilute nitric acid and Chloride ions will form a
aqueous silver nitrate white precipitate.
solution
Iodine Iodide ions will form a
yellow precipitate.

Nitrate Add sodium hydroxide, Damp red litmus paper turns

pieces of aluminium and blue and ammonia gas is
warm. released.
Sulfate Add dilute nitric acid and White precipitate will form if
aqueous Barium Nitrate Sulfate ions are present.
solution.
Flame Test Colors
Li+ Deep red (crimson)
Na+ Yellow
K+ Violet
Ca2+ Orange-red
Sr2+ Red
Ba2+ Green
Cu2+ Blue-green

Aqueous Ion Colors

Cu1+ Green
Cu2+ Blue
Fe Yellow to red-orange (depending on anion and charge of Fe); in
rare cases, can form complex ion with a deep blue color
Fe2+ yellow-green (depending on the anion)
Fe3+ orange-red (depending on the anion)
Co2+ Pink
Cr3+ Violet (Cr(NO3)3 to Green (CrCl3)
Ni2+ Green
Mn2+ Pink
Pb3+ blue-green (Pb2+ and Pb4+ are colorless)
V2+ violet
V3+ blue-green
MnO4- Purple (Mn w/ +7 oxidation state is purple)
CrO42- Yellow
Cr2O72- Orange
Cu(NH3)42+ Dark Blue; produced when ammonia is added to Cu2+ solutions
CoCl42- Blue (Co2+ with HCl will form a CoCl42- complex that is blue)

 Al, K, Li, Mg, Na, Ca, Ba, Sr, Zn are colorless aqueous ions and most of their solid salts are white.
 Transition element ions with partially filled d orbitals tend to release colored light.

Kamal Ahmed Ansari

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O Level Chemistry 5070 (Process and conditions)

Process Raw material Condition Equation
Haber process Nitrogen and hydrogen 450˚C, 200-300 atm and Iran N2 + 3H2 → 2NH3
catalyst
Contact process Sulphur, air and water 450˚C. 2-3atm and 2SO2+ + O2 → 2SO3
Vanadium(V)oxide catalyst
Extraction of Iron Haematite ore, cock, - C + O2 → CO2
lime stone and air CO2+C → 2CO
Fe2O3 + 3CO → 2Fe +
3CO3
CaCO3 + SiO2 → CaSiO3
+ CO2
Extraction of Aluminum Bauxite ore, sodium - Al2O3( s) +NaOH →
hydroxide, cryolite and Al(OH)3++ Heat → Al2O3
-3 -2
graphite electrodes (aq) → 2Al + 3O
Al-3 + 3e → Al
2O-2 → 4e + O2
C + O2 → CO2
Fermentation of Glucose Sugar and yeast 18-32˚C , yeast catalyst and C6H12O6 → 2C2H5OH +
in the absence of oxygen 2CO2
Industrial preparation of Alkene and steam 200-300˚C , high pressure C2H4 + H2O → C2H5OH
alcohol and phosphoric acid/ dil
sulphuric acid catalyst
Formation of margarine Alkene and hydrogen 180 ˚C and nickel catalyst C2H4 + H2 → C2H6
Cracking of Alkane Crude oil 400˚C and Silico (IV) oxide C4H10 → C2H4 + C2H6
or aluminum oxide catalyst
Preparation of carboxylic Alcohol and air Dil sulphuric acid and C2H5OH + O2 → CH-
acid potassium manganate (VII) or 3COOH + H2 O
( oxidation of alcohol) potassium dichromate (VI)
oxidizing agent
Esterification Alcohol and carboxylic Warm up and concentrated C2H5OH + CH3COOH →
acid sulphuric acid CH3COOC2H5 + H2O
Hydrolysis of ester Ester and water Sodium hydroxide CH3COOC2H5 + H2O →
C2H5OH + CH3COOH
Hydrolysis of Fats Fats and water Boiled with sodium -
(Formation of Fatty acid hydroxide and enzyme
and glycerol)
Hydrolysis of Proteins Protein and water Acidic medium and enzyme -
( Formation of amino
acid)
Hydrolysis of Carbohydrates and Boiled with hydrochloric acid -
carbohydrates (Formation water and enzyme
of sugar or glucose)

Kamal Ahmed Ansari 03350126177

Kamal Ahmed Ansari

 Reactivity series

Metal Reaction with cold water Reaction with steam

Potassium 2K(s) + 2H2O(l) -> 2KOH(aq) +H2(g) React explosively

Sodium 2Na(s) + 2H2O(l) -> 2NaOH(aq) +H2(g)

Calcium Ca(s) + 2H2O(l) -> Ca(OH)2(aq) + H2(g)

Magnesium Mg(s) + 2H2O(l) -> Mg(OH)2(s) +H2(g) Mg(s) + H2O(g) -> MgO(s) + H2(g)

Zinc No reaction Zn(s) + H2O(s) + H2O(g) -> ZnO(s) +H2(g)

Zinc oxide is yellow when hot and white when
cold
Iron No reaction (except rusting) 3Fe(s) + 4H2O(g) -> Fe3O4(g)
Reacts slowly, iron must be heated constantly

Lead No reaction No reaction

Copper
Silver

Most reactive to least reactive

K Na Ca Mg Zn Fe Pb H Cu Ag

A more reactive metal can displace a less reactive metal from its salt solution (redox reaction)
A more reactive metal can reduce the oxide of a less reactive metal

Action of heat on metal carbonates

Metal carbonate Observation
Potassium carbonate Unaffected by heat
Sodium carbonate
Calcium carbonate Decompose into metal oxide and carbon dioxide
Magnesium carbonate on heating
Zinc carbonate
Iron (II) carbonate
Lead(II) carbonate
Copper(II) carbonate
Silver carbonate Decomposes into silver and carbon dioxide on
heating
 Hardest to discharge to easiest to discharge
K+ Na+ Ca2+ MG2+ Zn2+ Fe2+ Pb2+ H+ Cu2+ Ag+

Hardest to discharge to easiest to discharge

SO42- NO3- Cl- Br- I- OH-

Manufacturing ammonia by Haber process

Nitrogen + hydrogen ⇌ ammonia (added in the ratio 1:3)
N2(g) + 3H2(g) -⇌ 2NH3(g)
Conditions: 250atm, 450°C, iron as catalyst
Only about 10-15% of nitrogen and hydrogen concerted to ammonia (ammonia gas cooled to liquid)

SO2 + H2O -> H2SO3 sulfurous acid

Sulfurous acid can be oxidized in air to form sulfuric acid
4NO2 + 2H2O + O2 -> 4HNO3

Reducing pollution
Catalytic converters
2CO(g) + O2(g) -> 2CO2(g)
2NO(g) + 2CO(g) -> N2(g) + 2CO2(g)
2C8H18(l) + 25O2(g) -> 16CO2(g) + 18H2O(g)

Flue Gas Desulfurisation (remove sulfur dioxide pollution)

CaCO3(s) + SO2(g) -> CaSO3(S) + CO2
2CaSO3(s) + O2(g) -> 2CaSO4(s)
CaO(s) + SO2(g) -> CaSO3(s)

Alkanes
Combustion
Alkane + oxygen -> carbon dioxide + water vapour
Substitution (under ultraviolet light)
E.g. methane + chlorine -> chloromethane + hydrogen chloride

Alkenes
Combustion
Alkene + oxygen -> carbon dioxide + water vapour
As alkenes have higher percentage of carbon than alkanes, alkenes will burn with a sootier flame

Alkenes can also undergo substitution reaction under UV light

An Addition reaction is a reaction in which an unsaturated organic compound combines with another
substance to form a single new compound
 Addition of hydrogen
Ethene + hydrogen -> ethane
Conditions: 200°C, nickel as catalyst
Convert vegetable oils to solid margarine
 Addition of bromine
Ethene + bromine -> 1,2-dibromooethane
Serve as a chemical test to distinguish between alkane and alkene
 Addition of steam
Ethene + steam -> ethanol
Conditions: 300°C, 60 atm, phosphoric (V) acid as catalyst
 Addition polymerization
Ethene -> poly(ethene)
Conditions: High temperature and pressure and catalyst

Alcohol
 Combustion
Alcohol + oxygen -> carbon dioxide + water vapour
Can be used as a fuel
Burnt on some food such as fruit cake to give it a distinct flavor

 Oxidation
Alcohol + oxidizing agent -> carboxylic acid + water
C2H5OH + 2[O] -> CH3COOH +H2O
(2 ways oxidation by acidified potassium manganate (VII) and oxidation by atmospheric oxygen)
Breathalyzer contains an oxidizing agent that has a colour agent when high level of alcohol detected

Producing ethanol
 From catalytic addition of steam to ethene
 Alcohol fermentation Glucose -> ethanol + carbon dioxide

Carboxylic acids
Are weak acids
Reaction with reactive metals (salts of ethanoic acid are known as ethanoates)
Reaction with carbonates
Reaction with bases
Reaction with alcohols to produce ester and water (esterification)

Ester
An ester is a colourless liquid that is insoluble in water
Ethanoic acid + methanol -> methyl ethanoate (concentrated sulfuric acid as catalyst)
First part of name from alcohol
Functional group

Polymerization
Additional polymerization occurs when unsaturated monomers join together without losing any
molecules or atoms.

Condensation polymerization occurs when monomers combine to form a polymer with the removal of a
small molecule such as water.
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Organic Compounds Reactions:

1. Alkane …………Alkene (Cracking/SiO2/Al2O3)

2. Alkene …………. Alkane (Hydrogenation or formation of margarine/Ni)
3. Alkene …………… Alcohol (Addition of water/H3PO4)
4. Alcohol ………… Carboxylic acid ( Oxidation / K2Cr2O7)
5.Alcohol + carboxylic acid ……………. Ester (Esterfication/H2SO4)

Fraction of Crude oil

Papa ne kha purana diesel lao beta

Pa Petroleum gases

Pa Petrol

Ne Naptha

Kaha Kerosene
Purana Paraffine
Deisel Deisel

Lao Lubricating oil

Beta Bitumen

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Reactivity series of metals (Cations) And Anions

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Soluble salts Insoluble salts

Without condition
Titration Precipitation
Condition: Condition:
Alkali +Acid Two soluble substances
Soluble salts Insoluble salts

With condition

Condition: Condition:
Metal oxide = Excess Metal oxide = limit
Acid = Limit Acid = Excess

Air Pollution
CO Incomplete combustion Reduces efficiency of - Install catalytic converters in
Forest fire hemoglobin to transport cars
Exhaust fumes oxygen. Cells then die. - Reduce number of cars on
road
SO2 Combustion of fossil fuels Lung irritant, Prevent using fuels containing
containing sulphur eye irritant, sulphur impurities
impurities; volcanic acid rain Desulphurization by using
eruptions CaCO3
NO/NO2 Lightning activity; Eutrophication, Install catalytic converters in
forest fires; lung damage, cars
internal combustion acid rain
CH4 Decomposition of It is highly flammable, Cattle and other ruminant
vegetable matter; greenhouse gas animals should be given
improved diet
Unburnt Internal combustion Carcinogenic, Install catalytic converters in
hydrocarbons engunes; forms photochemical cars
incomplete combustion of smog - Reduce number of cars on
hydrocarbons road
Ozone It’s created by reaction of It reacts with unburnt - Don’t use CFCs/replace it with
nitrogen oxides with hydrocarbons to form HCFCs which destroys faster
volatile organic photochemical smog that
compounds in presence causes headache, eye, nose
of UV radiation. and throat irritation.
Lead Combustion of leaded Causes lead poisoning Install catalytic converters in
compounds petrol in car engines which leads to brain cars
damage - Reduce number of cars on
road

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Increase the rate of reactions:

1.Temperature
2.Surface area of reactants
3.Concentration
4.Pressure (only for gases)
5.Catalyst
Note: double the factor = double the rate of reaction = half the tim

Reversible reactions increase the yield:

1. Temperature:
Exo thermic = decreases
Endo thermic = increases

2. Pressure
No of mole of reactants less then products = increases
No of mole of reactants more then products = decreases
No of mole of reactants = no of mole of products = no change

3. Concentration
Concentration of reactants increases = yield increases
Concentration of products increases = yield decreases

Kamal Ahmed Ansari