As fuels
4 marks · NormalThe table below shows information about some fractions obtained from crude oil.
| Fraction | Approximate Boiling Point (°C) | Main Use |
|---|---|---|
| Refinery gas | < 40 | Bottled gas |
| Gasoline | 40–100 | Fuel for cars |
| Diesel oil | 250–350 | Fuel for lorries |
| Bitumen | > 350 | Road surfacing |
Identify the fraction with the lowest boiling point and state its main use.
Which fraction is most likely to contain the largest hydrocarbon molecules? Explain your answer using data from the table.
Suggest why bitumen is not used as a fuel.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Refinery gas; used as bottled gas · must show refinery gas, bottled gas
(b) Bitumen; because it has the highest boiling point, so it contains the largest hydrocarbon molecules. · must show bitumen, reason based on largest molecule/high boiling point
(c) It is a solid or very thick liquid and does not burn easily. · must show not burn easily, solid/very thick
Common mistakes: confusing position of fractions with boiling points
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Names refinery gas and its main use as bottled gas.
B2 (b) · 1 mark · Identifies bitumen as the fraction with the largest molecules.
M1 (b) · 1 mark · Links largest molecules to highest boiling point using data from the table.
B3 (c) · 1 mark · States bitumen is not used as a fuel because it is a solid/very thick liquid and doesn't burn easily.
Worked solution
a) The fraction with the lowest boiling point is refinery gas; its main use is as bottled gas.
b) Bitumen contains the largest hydrocarbon molecules, because it has the highest boiling point according to the data in the table.
c) Bitumen is not used as a fuel because it is a solid or very thick liquid that does not burn easily.