DP Chemistry (first assessment 2025)
Question 22N.1A.HL.TZ0.17
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.HL.TZ0.17 |
| Level | HL | Paper | 1A | Time zone | TZ0 |
| Command term | State | Question number | 17 | Adapted from | N/A |
17.
[Maximum mark: 1]
22N.1A.HL.TZ0.17
At which temperature could ΔH, ΔS, and ΔG all be positive?
A. High temperatures
B. Low temperatures
C. Any temperature
D. No temperature
[1]
Markscheme
B
Examiners report
Nearly 70% of the candidates managed to deduce that ΔH, ΔS, and ΔG can only all be positive at low temperatures, when the contribution of entropy to free energy is minimal. The distractors were all about equally favoured.
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.