DP Chemistry (first assessment 2025)
Question 22M.2.SL.TZ1.3b(ii)
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.2.SL.TZ1.3b(ii) |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | b(ii) | Adapted from | N/A |
b(ii).
[Maximum mark: 1]
22M.2.SL.TZ1.3b(ii)
(b(ii))
Outline why the value obtained in (b)(i) might differ from a value calculated using ΔHf data.
[1]
Markscheme
«N-H» bond enthalpy is an average «and may not be the precise value in NH3» ✔
Accept ΔHf data are more accurate / are not average values.
Examiners report
Outlining why ΔHrxn based on BE values differ due to being average compared to using ΔHf values was generally done well.
