DP Chemistry (last assessment 2024)

Question 22M.2.sl.TZ1.2d(ii)

Date	May 2022	Marks available	[Maximum mark: 1]	Reference code	22M.2.sl.TZ1.2d(ii)
Level	sl	Paper	2	Time zone	TZ1
Command term	Calculate	Question number	d(ii)	Adapted from	N/A

d(ii).

[Maximum mark: 1]

22M.2.sl.TZ1.2d(ii)

Ammonia, NH₃, is industrially important for the manufacture of fertilizers, explosives and plastics.

The effect of temperature on the position of equilibrium depends on the enthalpy change of the reaction.

(d(ii))

Calculate the enthalpy change, ΔH^⦵, for the Haber–Bosch process, in kJ, using the following data.

$∆ H_{f}^{⦵} ({NH}_{3}) = - 46.2 kJ {mol}^{- 1}$ .

[1]

Markscheme

–92.4 «kJ» ✔

Examiners report

Very few students could determine the enthalpy change from enthalpy of formation data, with many being baffled by the absence of values for the elemental reactants and more than half who overcame this obstacle failed to note that 2 moles of ammonia are produced.

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Core

Core » Topic 5: Energetics/thermochemistry » 5.2 Hess’s Law

Core » Topic 5: Energetics/thermochemistry

Question 22M.2.sl.TZ1.2d(ii)

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