DP Chemistry (first assessment 2025)

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Question 22M.2.HL.TZ1.3c(iii)

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Date May 2022 Marks available [Maximum mark: 2] Reference code 22M.2.HL.TZ1.3c(iii)
Level HL Paper 2 Time zone TZ1
Command term Calculate Question number c(iii) Adapted from N/A
c(iii).
[Maximum mark: 2]
22M.2.HL.TZ1.3c(iii)
(c(iii))

Calculate the entropy change for the Haber–Bosch process, in J mol–1 K–1 at 298 K. Use your answer to (b)(i) and section 1 of the data booklet.

[2]

Markscheme

ΔG = «ΔH – TΔS =» –93000 «J» – 298«K» × ΔS = –33000 ✔

ΔS = 〈〈-93000 J --33000 J298 K〉〉 = –201 «J mol–1 K–1» ✔

 

Do not penalize failure to convert kJ to J in both (c)(ii) and (c)(iii).

Award [2] for correct final answer

Award [1 max] for (+) 201 «J mol–1 K–1».

Award [2] for –101 or –100.5 «J mol–1 K–1».

Examiners report

Very good performance; since the unit for S is J mol˗1 K˗1, ΔG and ΔH needed to be converted from kJ to J, but that was not done in some cases.

Syllabus sections