DP Chemistry (first assessment 2025)

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Question 21M.2.SL.TZ2.1a

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

Calcium carbonate is heated to produce calcium oxide, CaO.

CaCO3 (s) → CaO (s) + CO2 (g)

Calculate the volume of carbon dioxide produced at STP when 555 g of calcium carbonate decomposes. Use sections 2 and 6 of the data booklet.

[2]

Markscheme

«nCaCO3 = 555 g11.09 g mol-1=» 5.55 «mol» ✓

«V = 5.55 mol × 22.7 dm3 mol−1 =» 126 «dm3» ✓


Award [2] for correct final answer.

Accept method using pV = nRT to obtain the volume with p as either 100 kPa (126 dm3) or 101.3 kPa (125 dm3).

Do not penalize use of 22.4 dm3 mol–1 to obtain the volume (124 dm3).

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