DP Chemistry (first assessment 2025)
Question 21N.2.HL.TZ0.c(ii)
| Date | November 2021 | Marks available | [Maximum mark: 1] | Reference code | 21N.2.HL.TZ0.c(ii) |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate | Question number | c(ii) | Adapted from | N/A |
c(ii).
[Maximum mark: 1]
21N.2.HL.TZ0.c(ii)
Calculate the entropy change, ΔS, in J K−1 mol−1, for this reaction.
Chemistry 2e, Chpt. 21 Nuclear Chemistry, Appendix G: Standard Thermodynamic Properties for Selected Substances https://openstax.org/books/chemistry-2e/pages/g-standard-thermodynamic-properties-for- selectedsubstances# page_667adccf-f900-4d86-a13d-409c014086ea © 1999-2021, Rice University. Except where otherwise noted, textbooks on this site are licensed under a Creative Commons Attribution 4.0 International License. (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/.
[1]
Markscheme
«ΔS = 364.5 J K–1 mol–1 – (311.7 J K–1 mol–1 + 223.0 J K–1 mol–1)=» –170.2 «J K–1 mol–1» ✔
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⦵.