DP Chemistry (last assessment 2024)

Question 22M.2.sl.TZ2.1b(ii)

Date	May 2022	Marks available	[Maximum mark: 2]	Reference code	22M.2.sl.TZ2.1b(ii)
Level	sl	Paper	2	Time zone	TZ2
Command term	Calculate	Question number	b(ii)	Adapted from	N/A

b(ii).

[Maximum mark: 2]

22M.2.sl.TZ2.1b(ii)

Lithium reacts with water to form an alkaline solution.

A 0.200 g piece of lithium was placed in 500.0 cm³ of water.

(b(ii))

Calculate the volume of hydrogen gas produced, in cm³, if the temperature was 22.5 °C and the pressure was 103 kPa. Use sections 1 and 2 of the data booklet.

[2]

Markscheme

$« n_{H_{2}} = \frac{1}{2} \times 0.0288 m o l = 0.0144 m o l »$

$« V = \frac{n R T}{P} = » (\frac{0.0144 m o l \times 8.31 J K^{- 1} m o l^{- 1} \times (22.5 + 273) K}{103 k P a}) « \times 10^{3} »$ ✔

$V = 343 « {cm}^{3} »$ ✔

Award [2] for correct final answer.

Accept answers in the range 334 – 344 cm³.

Award [1 max] for 0.343 «cm³/dm³/m³».

Award [1 max] for 26.1 cm³ obtained by using 22.5 K.

Award [1 max] for 687 cm³ obtained by using 0.0288 mol.

Syllabus sections

Core

Core » Topic 1: Stoichiometric relationships » 1.3 Reacting masses and volumes

Core » Topic 1: Stoichiometric relationships

Question 22M.2.sl.TZ2.1b(ii)

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