DP Chemistry (first assessment 2025)

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Question 19M.1A.HL.TZ1.16

Date	May 2019	Marks available	[Maximum mark: 1]	Reference code	19M.1A.HL.TZ1.16
Level	HL	Paper	1A	Time zone	TZ1
Command term		Question number	16	Adapted from	N/A

16.

[Maximum mark: 1]

19M.1A.HL.TZ1.16

Which is correct for the reaction H₂O (g) → H₂O (l) ?

A. Enthalpy increases and entropy increases.

B. Enthalpy decreases and entropy increases.

C. Enthalpy increases and entropy decreases.

D. Enthalpy decreases and entropy decreases.

[1]

Markscheme

D

Examiners report

Higher scoring candidates had more success understanding enthalpy and entropy decreases.

Syllabus sections

Reactivity 1. What drives chemical reactions? » Reactivity 1.4—Entropy and spontaneity (Additional higher level) » Reactivity 1.4.2—Change in Gibbs energy, ΔG, relates the energy that can be obtained from a chemical reaction to the change in enthalpy, ΔH, change in entropy, ΔS, and absolute temperature, T. Apply the equation ΔG⦵ = ΔH⦵ − TΔS⦵ to calculate unknown values of these terms.