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9.1 Fuels

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Question 16
H

Hexadecane, C16H34\mathrm{C_{16}H_{34}}C16​H34​, from the diesel oil fraction can be cracked to make octane for petrol and alkenes for making polymers.

C16H34→C8H18+2C3H6+X\mathrm{C_{16}H_{34}} \rightarrow \mathrm{C_{8}H_{18}} + \mathrm{2C_{3}H_{6}} + \mathrm{X}C16​H34​→C8​H18​+2C3​H6​+X

a.

Deduce the formula of X.

[1]
b.

Explain why C8H18\mathrm{C_{8}H_{18}}C8​H18​ is an alkane but C3H6\mathrm{C_{3}H_{6}}C3​H6​ is not.

[2]
c.

Calculate the maximum mass of octane that can be made by cracking 452 kg of hexadecane. Relative atomic masses: C = 12, H = 1

[4]
d.

Calculate the atom economy for making octane by this reaction.

[2]
e.

Suggest why the refinery considers this process worthwhile even though the atom economy for making octane is low.

[1]
Markscheme

9.1 Fuels Questions

  1. GCSE
  2. /Chemistry
  3. /9.1 Fuels

37 exam-style questions on Edexcel GCSE Chemistry 9.1 Fuels, covering 9.1.1 Hydrocarbons and crude oil, 9.1.2 Fractional distillation of crude oil and its fractions, 9.1.3 The alkanes as a homologous series, 9.1.4 Complete and incomplete combustion, 9.1.5 Pollutants from burning fuels, 9.1.6 Hydrogen as a fuel and non-renewable fossil fuels, and 9.1.7 Cracking of larger alkanes. Each one has a worked solution and a mark scheme showing where the marks go.

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