DP Chemistry (last assessment 2024)

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Question 18M.2.sl.TZ1.3b.iii

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.2.sl.TZ1.3b.iii
Level sl Paper 2 Time zone TZ1
Command term Explain, Justify Question number b.iii Adapted from N/A
b.iii.
[Maximum mark: 2]
18M.2.sl.TZ1.3b.iii

This question is about ethene, C2H4, and ethyne, C2H2.

(b.iii)

Explain, giving two reasons, the difference in the values for (b)(i) and (ii). If you did not obtain answers, use −475 kJ for (i) and −600 kJ for (ii).

[2]

Markscheme

ΔHf values are specific to the compound

OR

bond enthalpy values are averages «from many different compounds»

 

condensation from gas to liquid is exothermic

 

Accept “benzene is in two different states «one liquid the other gas»“ for M2.

[2 marks]

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