Recall that hydrocarbons are compounds that contain carbon and hydrogen only

Describe crude oil as:

a) a complex mixture of hydrocarbons
b) containing molecules in which carbon atoms are in chains or rings (names, formulae and structures of specific ring molecules not required)
c) an important source of useful substances (fuels and feedstock for the petrochemical industry)
d) a finite resource

Describe and explain the separation of crude oil into simpler, more useful mixtures by the process of fractional distillation

Recall the names and uses of the following fractions:

a) gases, used in domestic heating and cooking
b) petrol, used as fuel for cars
c) kerosene, used as fuel for aircraft
d) diesel oil, used as fuel for some cars and trains
e) fuel oil, used as fuel for large ships and in some power stations
f) bitumen, used to surface roads and roofs

Explain how hydrocarbons in different fractions differ from each other in:

a) the number of carbon and hydrogen atoms their molecules contain
b) boiling points
c) ease of ignition
d) viscosity

and are mostly members of the alkane homologous series

Explain an homologous series as a series of compounds which:

a) have the same general formula
b) differ by CH₂ in molecular formulae from neighbouring compounds
c) show a gradual variation in physical properties, as exemplified by their boiling points
d) have similar chemical properties

Describe the complete combustion of hydrocarbon fuels as a reaction in which:

a) carbon dioxide and water are produced
b) energy is given out

Explain why the incomplete combustion of hydrocarbons can produce carbon and carbon monoxide

Explain how carbon monoxide behaves as a toxic gas

Describe the problems caused by incomplete combustion producing carbon monoxide and soot in appliances that use carbon compounds as fuels

Explain how impurities in some hydrocarbon fuels result in the production of sulfur dioxide

Explain some problems associated with acid rain caused when sulfur dioxide dissolves in rain water

Explain why, when fuels are burned in engines, oxygen and nitrogen can react together at high temperatures to produce oxides of nitrogen, which are pollutants

Evaluate the advantages and disadvantages of using hydrogen, rather than petrol, as a fuel in cars

Recall that petrol, kerosene and diesel oil are non-renewable fossil fuels obtained from crude oil and methane is a non-renewable fossil fuel found in natural gas

Explain how cracking involves the breaking down of larger, saturated hydrocarbon molecules (alkanes) into smaller, more useful ones, some of which are unsaturated (alkenes)

Explain why cracking is necessary