DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ2.b

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.hl.TZ2.b
Level hl Paper 3 Time zone TZ2
Command term Determine Question number b Adapted from N/A
b.
[Maximum mark: 2]
19M.3.hl.TZ2.b

This question is about fuel for engines.

Determine the specific energy, in kJ g−1, and energy density, in kJ cm−3, of hexane, C6H14. Give both answers to three significant figures.

Hexane: Mr = 86.2; ΔHc = −4163 kJ mol−1; density = 0.660 g cm−3

Specific energy:

Energy density:

[2]

Markscheme

specific energy = «  4163  kJ mo l − 1 86.2  g mo l − 1 =» 48.3 «kJ g–1»  [✔]

energy density = «48.3 kJ g–1 × 0.660 g cm–3 =» 31.9 «kJ cm–3»  [✔]

 

Note: Award [1 max] if either or both answers not expressed to three significant figures.

Examiners report

This part was very well answered by most candidates with the correct number of significant digits as specified in the question.

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