DP Chemistry (first assessment 2025)
Question 22M.2.HL.TZ1.c(iv)
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.2.HL.TZ1.c(iv) |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | c(iv) | Adapted from | N/A |
c(iv).
[Maximum mark: 1]
22M.2.HL.TZ1.c(iv)
Outline, with reference to the reaction equation, why this sign for the entropy change is expected.
[1]
Markscheme
«forward reaction involves» decrease in number of moles «of gas» ✔
Examiners report
Average performance for sign of the entropy change expected for the reaction. Some answers were based on ΔG value rather than in terms of decrease in number of moles of gas or had no idea how to address the question.
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⦵.