DP Chemistry (last assessment 2024)

Question 22N.2.hl.TZ0.1d.ii

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

d.ii.

[Maximum mark: 2]

22N.2.hl.TZ0.1d.ii

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

Cold packs contain ammonium nitrate and water separated by a membrane.

(d.ii)

Determine the mass of ammonium nitrate in the cold pack using your answer obtained in (d)(i) and and sections 6 and 19 of the data booklet.

If you did not obtain an answer in (d)(i), use 3.11 × 10³ J, although this is not the correct answer.

[2]

Markscheme

« $2.58 \times 10^{3} J \times \frac{1 k J}{1000 J} \times \frac{1 m o l}{25.69 k J} =$ » $0.100$ «mol» ✔

« $0.100$ mol $\times 80.06$ g mol⁻¹ =» 8.01 «g» ✔

Award [2] for the correct final answer.

Accept range of $8.0 - 8.1$ g.

If $3.11 \times 10^{3}$ J used then answer is $9.69$ g.

Examiners report

Almost ¾ of students managed to combine the previous answer with the enthalpy change of solution, from the data booklet, to calculate the amount, and hence the mass, of solute that had dissolved.

Syllabus sections

Core

Core » Topic 5: Energetics/thermochemistry » 5.1 Measuring energy changes

Core » Topic 5: Energetics/thermochemistry

Question 22N.2.hl.TZ0.1d.ii

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