DP Chemistry (last assessment 2024)
Question 22M.2.hl.TZ2.c(ii)
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.hl.TZ2.c(ii) |
| Level | hl | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | c(ii) | Adapted from | N/A |
c(ii).
[Maximum mark: 2]
22M.2.hl.TZ2.c(ii)
Sulfur trioxide is produced from sulfur dioxide.
2SO2 (g) + O2 (g) 2SO3 (g) ΔH = −196 kJ mol−1
Explain the electron domain geometry of SO3.
[2]
Markscheme
three electron domains «attached to the central atom» ✔
repel/as far away as possible /120° «apart» ✔
Examiners report
Most were focussed on the shape itself instead of explaining what led them to suggest that shape; number of electron domains allowed most candidates to get one mark and eventually a mention of bond angles resulted in only 35% getting both marks. In general, students were not able to provide clear explanations for the shape (not a language issue) but rather were happy to state the molecular geometry which they knew, but wasn't what was actually required for the mark.
