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Question 18M.3.sl.TZ1.10c.i

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.sl.TZ1.10c.i
Level sl Paper 3 Time zone TZ1
Command term Determine Question number c.i Adapted from N/A
c.i.
[Maximum mark: 2]
18M.3.sl.TZ1.10c.i

The increased concentration of carbon dioxide in the atmosphere is thought to result from the increased combustion of fossil fuels such as petroleum.

(c.i)

Determine the specific energy and energy density of petrol (gasoline), using data from sections 1 and 13 of the data booklet. Assume petrol is pure octane, C8H18. Octane: molar mass = 114.26 g mol−1, density = 0.703 g cm−3.

[2]

Markscheme

specific energy «= energy released mass consumed =  5470  kJ mo l − 1 114.26  g mo l − 1 » = 47.9 «kJ g–1»

energy density « energy released volume consumed = specific energy × density = 47.9 kJ g–1 × 0.703 g cm–3» = 33.7 «kJ cm–3 »

 

Do not accept “–47.9 «kJ g–1»”.

Do not accept “–33.7 «kJ cm–3»” unless “–47.9 «kJ g–1»” already penalized.

[2 marks]

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