DP Chemistry (last assessment 2024)

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Question 22N.2.hl.TZ0.d.v

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

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

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

Calculate the standard entropy change, ΔS⦵, for the dissolution of ammonium nitrate.

S⦵NH4NO3 (s) = 151.1 J mol−1 K−1

S⦵NH4NO3 (aq) = 259.8 J mol−1 K−1

[1]

Markscheme

«ΔS°=259.8 J mol-1 K-1-151.1 J mol-1 K-1=» 108.7 «J mol−1 K−1» ✔

Examiners report

Almost all students managed to combine the standard entropies of the reactant and product to determine the increase in entropy, though a handful managed to end up with a negative sign.

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