Edexcel Igcse Chemistry Notes

Front 1

Edexcel IGCSE Chemistry notes

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1. C1

2. C2

3. C3

4. C4

5. C5

Front 2

C1 revision notes

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Front 3

1.1 understand the arrangement, movement and energy of the particles in each of the three states of matter: solid, liquid and gas

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Solids:

- Low energy

- Very restricted movement (can only vibrate)

- Strong bonds

Liquids:

- Medium energy

- Free to move around each other

- Weaker bonds

Gases:

- High energy

- Free movement anywhere

- No bonds

Front 4

1.2 understand how the interconversions of solids, liquids and gases are achieved and recall the names used for these interconversions

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Solid > liquid

Process called melting. Heat is applied

Liquid > solid

Called freezing/ solidifying. Heat energy is taken away

Liquid > gas

Heat is added process is called evaporation

Gas > liquid

Removing heat. Process is called condensing

Front 5

C5 revision notes

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Front 6

5.6 understand that crude oil is a mixture of hydrocarbons

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Crude oil is a mixture of different molecules that are only made of hydrogen and carbon

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5.7 describe and explain how the industrial process of fractional distillation separates crude oil into fractions

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-There are many different hydrocarbons in crude oil and

- Each has a different boiling point so will condense at different temperatures

- Each fraction is a different hydrocarbon

Front 8

1.7 describe experimental techniques for the separation of mixtures, including fracti onal distillation

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Fractional distillation

The mixture is evaporated and rises up the tube.Different substances have different boiling points and so will condense at different temperatures; as the mixture travels up the tube the temperature decreases, substances begin to condense at different places (due to the change in temperature) and are collected. This separates the mixture into its different parts.

Front 9

5.8 recall the names and uses of the main fractions obtained from crude oil: refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

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Bitumen: roads, roofs

Fuel: ships, power stations

Diesel: cars, ferries, busses

Kerosine: aircrafts

Naphtha: making chemicals

Gasoline: cars

Refinery gases: bottled gas

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5.9 describe the trend in boiling point and viscosity of the main fractions

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- Fractions with low boiling point are less viscous (less thick)

-Fractions with a high boiling point are more viscous (more thick)

Front 11

3.1 explain the terms homologous series, hydrocarbon, saturated, unsaturated, general formula and isomerism.

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Compounds

- same homologous series have the same general formula and similar chemical properties.

Hydrocarbon

- compound made up only of hydrogen and carbon

Saturated

- Something has bonded as many time as possible.

Unsaturated

- More bonds can be made

General formula

- Most simplified the ratio of molecules can be.Isomers have the same general formula but different structures.

Front 12

3.2 recall that alkanes have the general formula CnH2n +2

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- Alkanes is a homologous series with the formula CnH2n +2

- This means that for every one carbon there are two times the amount of hydrogens plus two more hydrogens

Front 13

3.3 draw displayed formulae for alkanes with up to five carbon atoms in a molecule, and name the straight-chain isomers

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Methane: CH4

Ethane: C2H6

Propane: C3H8

Butane: C4H10

Pentane: C5H12

Front 14

3.4 recall the products of the complete and incomplete combustion of alkanes

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Products of incomplete combustion are:

- Carbon monoxide

- Water

Front 15

5.10 understand that incomplete combustion of fuels may produce carbon monoxide and explain that carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen

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- Carbon monoxide combines with haemoglobin in red blood cells meaning they can't carry oxygen around the body

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2.24 understand that carbon dioxide is a greenhouse gas and may contribute to climate change

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Carbon dioxide prevents heat leaving the earth's atmosphere

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5.13 understand that fractional distillation of crude oil produces more long-chain hydrocarbons than can be used directly and fewer short-chain hydrocarbons than required and explain why this makes cracking necessary

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- Long chain hydrocarbons are less flammable and more viscous.

- Short chain hydrocarbons burn well and flow well

- Long chain hydrocarbons can be cracked which breaks them up into short chain ones.

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5.14 describe how long-chain alkanes are converted to alkenes and shorter-chain alkanes by catalytic cracking, using silica or alumina as the catalyst and a temperature in the range of 600–700C.

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- Long chain hydrocarbons are passed over a hot catalyst (silica or alumina at 600-700 degrees) - This causes them to break down into smaller molecules

- As some atoms are lost from molecules, they become unsaturated and can therefore form a double bond

- This is how you get alkenes from the process as well as shorter chain alkanes.

Front 19

3.6 recall that alkenes have the general formula CnH2n

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All compounds in the homologous group alkenes have the general formula CnH2n.

Front 20

3.7 draw displayed formulae for alkenes with up to four carbon atoms in a molecule, and name the straight-chain isomers.

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- Every alkene there is one double bond between two carbons

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3.8 describe the addition reaction of alkenes with bromine, including the decolourising of bromine water as a test for alkenes

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Bromine water is a dilute solution of bromine that is normally orange-brown in colour,

- Becomes colourless when shaken with an alkene

- Alkenes can de-colour bromine water, while alkanes cannot

- C2H4(g) + Br2 (aq) → C2H4Br2 (aq)

Front 22

3.5 describe the substitution reaction of methane with bromine to form bromomethane in the presence of UV light.

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- In UV light bromine and methane will form bromomethane:

- CH4 + Br2CH3Br + HBr

Front 23

5.15 understand that an addition polymer is formed by joining up many small molecules called monomers

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- Monomer is a molecule that can be bonded to other identical molecules to form a polymer

- Alkene with double bond and if the bond is broken there can be other things bonded to it

- If a carbon from another monomer is bonded in then a chain can be created to eventually form a polymer

Front 24

5.16 draw the repeat unit of addition polymers, including poly(ethene), poly(propene) and poly(chloroethene)

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Front 25

5.17 deduce the structure of a monomer from the repeat unit of an addition polymer

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- Structure of a monomer can be deduced from a polymer

- This is because instead of having floating bonds either side it has a double bond between the two carbons

Front 26

5.18 describe some uses for polymers, including poly(ethene), poly(propene) and poly(chloroethene)

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Polyethene: plastic carrier bags, plastic bottles

Polypropene: crates, ropes

Polychloroethene: piping, cable insulation

Front 27

5.19 explain that addition polymers are hard to dispose of as their inertness means that they do not easily biodegrade

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- Polymers are saturated so the don't react much - This means that they don't decompose easily

Front 28

5.20 understand that some polymers, such as nylon, form by a different process called condensation polymerisation

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Front 29

5.21 understand that condensation polymerisation produces a small molecule, such as water, as well as the polymer

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Front 30

3.9 describe the manufacture of ethanol by passing ethene and steam over a phosphoric acid catalyst at a temperature of about 300°C and a pressure of about 60–70 atm

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Front 31

3.10 describe the manufacture of ethanol by the fermentation of sugars, for example glucose, at a temperature of about 30°C

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Front 32

3.11 evaluate the factors relevant to the choice of method used in the manufacture of ethanol, for example the relative availability of sugar cane and crude oil

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Front 33

3.12 describe the dehydration of ethanol to ethene, using aluminium oxide.

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Front 34

4.10 understand that chemical reactions in which heat energy is given out are described as exothermic and those in which heat energy is taken in are endothermic

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- In an exothermic reaction heat is given out because bonds are made which gives out energy

- In an endothermic reaction energy is taken in because bonds are being broken

Front 35

4.13 understand the use of ΔH to represent enthalpy change for exothermic and endothermic reactions

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- ΔH is the symbol that represents the amount of energy lost or gained in a reaction

- +ΔH is endothermic (because it gains heat)

- -ΔH is exothermic (because it looses heat)

Front 36

4.14 represent exothermic and endothermic reactions on a simple energy level diagram

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- Exothermic: lower energy level at end

- Endothermic: high energy level at end

Front 37

4.11 describe simple calorimetry experiments for reactions such as combustion, displacement, dissolving and neutralisation in which heat energy changes can be calculated from measured temperature changes

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1. Measure the required amount of each substance

2. Record the temperature of any liquids before mixing

3. Mix the reactants in a polystyrene cup

4. Measure the temperature

5. How ever much heat has gone up or down is the calorimetry of the reaction

HEAT GOES UP = EXOTHERMIC

HEAT GOES DOWN = ENDOTHERMIC

Front 38

4.12 calculate molar enthalpy change from heat energy change

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Front 39

4.15 understand that the breaking of bonds is endothermic and that the making of bonds is exothermic

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- Breaking bonds requires energy, this takes in heat so there for it is endothermic

- Making bonds releases energy, this gives out heat so therefore it is exothermic.

Front 40

4.16 use average bond energies to calculate the enthalpy change during a simple chemical reaction

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