DP Chemistry (last assessment 2024)

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Question 21M.2.hl.TZ2.1b(ii)

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Date May 2021 Marks available [Maximum mark: 1] Reference code 21M.2.hl.TZ2.1b(ii)
Level hl Paper 2 Time zone TZ2
Command term Calculate Question number b(ii) Adapted from N/A
b(ii).
[Maximum mark: 1]
21M.2.hl.TZ2.1b(ii)

Limestone can be converted into a variety of useful commercial products through the lime cycle. Limestone contains high percentages of calcium carbonate, CaCO3.

Thermodynamic data for the decomposition of calcium carbonate is given.

(b(ii))

Calculate the change in entropy, ΔS, in J K−1, for the decomposition of calcium carbonate.

[1]

Markscheme

«ΔS = (40 J K−1 + 214 J K−1) − (93 J K−1) =» 161 «J K−1» ✓


Ignore an extra step to determine total entropy change in JK–1: 161 J mol–1K–1 x 5.55 mol = 894 «J mol–1K–1»

Award [1] for 894 «J mol–1K–1».

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