DP Chemistry (first assessment 2025)

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Question 22M.2.HL.TZ2.4d(i)

Date	May 2022	Marks available	[Maximum mark: 1]	Reference code	22M.2.HL.TZ2.4d(i)
Level	HL	Paper	2	Time zone	TZ2
Command term	Calculate	Question number	d(i)	Adapted from	N/A

d(i).

[Maximum mark: 1]

22M.2.HL.TZ2.4d(i)

(d(i))

Calculate the entropy change of reaction, ΔS^⦵, in J K⁻¹ mol⁻¹.

[1]

Markscheme

«Δ ${S^{⦵}}_{reaction}$ = 2 × 206.6 – (130.6 + 116.1) =» 166.5 «J K^–1 mol^–1» ✔

Examiners report

ΔS was well calculated in general except for some inverted calculations or failure to consider the ratios of the reactants.

Syllabus sections

Reactivity 1. What drives chemical reactions? » Reactivity 1.4—Entropy and spontaneity (Additional higher level) » Reactivity 1.4.1—Entropy, S, is a measure of the dispersal or distribution of matter and/or energy in a system. The more ways the energy can be distributed, the higher the entropy. Under the same conditions, the entropy of a gas is greater than that of a liquid, which in turn is greater than that of a solid. Predict whether a physical or chemical change will result in an increase or decrease in entropy of a system. Calculate standard entropy changes, ΔS⦵, from standard entropy values, S⦵.