DP Chemistry (last assessment 2024)

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Question 22N.2.sl.TZ0.1f.ii

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Date November 2022 Marks available [Maximum mark: 2] Reference code 22N.2.sl.TZ0.1f.ii
Level sl Paper 2 Time zone TZ0
Command term Calculate Question number f.ii Adapted from N/A
f.ii.
[Maximum mark: 2]
22N.2.sl.TZ0.1f.ii

Ammonium nitrate, NH4NO3, is used as a high nitrogen fertilizer.

Solid ammonium nitrate can decompose to gaseous dinitrogen monoxide and liquid water.

(f.ii)

Calculate the volume of dinitrogen monoxide produced at STP when a 5.00 g sample of ammonium nitrate decomposes. Use section 2 of the data booklet.

[2]

Markscheme

«5.00 g ÷ 80.06 g mol−1 =» 0.0625 mol «NH4NO3» ✔

«1:1 mol ratio»

«0.0625 mol N2O×22.7 dm3mol=» 1.42 «dm3» ✔

 

Award [2] for correct final answer.

Accept range 1.36 – 1.43 «dm3».

Accept calculations based on PV=nRT.

Examiners report

This question was well answered though some candidates made silly mistakes. 60% of the candidates calculated the volume of gaseous product correctly. The majority used PV = nRT instead of the molar volume of 22.7 dm3. The question discriminated well between high achieving and low achieving candidates.

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