AQA GCSE Chemistry (8462), Higher tier · Organic chemistry › Carbon compounds as fuels and feedstock
Practise Fractional distillation and petrochemicals. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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The fractions from crude oil are processed to produce fuels and feedstock for the petrochemical industry. What is meant by feedstock?
A raw material used to make other chemicals.
Where in the fractionating column is the fraction with the lowest boiling points collected?
At the top
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy2 marks
(a) Which property mainly determines the height at which a hydrocarbon condenses inside a fractionating column? Tick (✓) one box.[1]
Its colour
Its boiling point
Its density as a solid
Its reactivity with bromine water
(b) Where in the fractionating column is the fraction with the lowest boiling points collected?[1]
Show the answer and mark scheme
(a)Answer: Its boiling point
(b)Answer: At the top
at the top (of the column)
Question 2Medium6 marks
The fractions from crude oil are processed to produce fuels and feedstock for the petrochemical industry.
(a) What is meant by feedstock?[1]
(b) Explain why there is a vast array of different carbon compounds.[2]
(c) Explain how modern life depends on the products from crude oil. Give examples in your answer.[3]
Show the answer and mark scheme
(a)Answer: A raw material used to make other chemicals.
a raw material used to make other chemicals / products
(b)Answer: Carbon atoms can bond to other carbon atoms, forming chains of different lengths and families of similar compounds.
carbon atoms can form (covalent) bonds with other carbon atoms
to make chains (or rings) of different lengths / families of similar compounds (homologous series)
(c)Answer: Fuels for transport (petrol, diesel oil, kerosene) and heating; polymers made from petrochemicals; solvents, lubricants and detergents.
fuels for transport, e.g. petrol, diesel oil or kerosene for aircraft
fuels for heating, cooking or power, e.g. liquefied petroleum gases or heavy fuel oil
polymers (plastics) made from petrochemicals
solvents, lubricants or detergents
Question 3Hard4 marks
A technician wants to separate a laboratory mixture of two miscible liquid hydrocarbons with different boiling points (hexane, boiling point 69 °C, and octane, boiling point 126 °C).
Describe how the technician could separate this mixture in a school or college laboratory. Name the apparatus needed.[4]
Show the answer and mark scheme
Answer: Set up fractional distillation apparatus: heat the mixture with an electric heater in a flask fitted with a fractionating column and a thermometer, leading to a condenser and a collecting vessel. Hexane (the lower-boiling liquid) distils over first and is collected while the thermometer reads about 69 °C; the collecting vessel is then changed, and octane is collected when the temperature reaches about 126 °C.
fractional distillation apparatus: a flask fitted with a fractionating column, a thermometer at the top of the column, a condenser and a collecting vessel
heat the mixture with an electric heater (not a naked flame, because hydrocarbons are flammable); hexane (the lower-boiling-point liquid) evaporates first
collect the liquid that distils over while the thermometer reads about 69 °C (hexane), then change the collecting vessel
continue heating and collect the second fraction when the temperature reaches about 126 °C (octane)