DP Chemistry (first assessment 2025)
Question 22M.1A.HL.TZ2.15
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.HL.TZ2.15 |
| Level | HL | Paper | 1A | Time zone | TZ2 |
| Command term | Apply | Question number | 15 | Adapted from | N/A |
15.
[Maximum mark: 1]
22M.1A.HL.TZ2.15
What are the signs of ΔH and ΔS for a reaction that is non-spontaneous at low temperatures but spontaneous at high temperatures?
[1]
Markscheme
D
Examiners report
Two-thirds of the candidates related information about the spontaneity of a reaction at different temperatures to the signs of ΔH and ΔS correctly. This question discriminated well between high-scoring and low-scoring candidates.
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.