DP Chemistry (first assessment 2025)
Question 21M.2.HL.TZ2.1b(i)
| Date | May 2021 | Marks available | [Maximum mark: 2] | Reference code | 21M.2.HL.TZ2.1b(i) |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Calculate | Question number | b(i) | Adapted from | N/A |
b(i).
[Maximum mark: 2]
21M.2.HL.TZ2.1b(i)
(b(i))
Calculate the enthalpy change of reaction, ΔH, in kJ, for the decomposition of calcium carbonate.
[2]
Markscheme
«ΔH =» (−635 «kJ» – 393.5 «kJ») – (−1207 «kJ») ✓
«ΔH = + » 179 «kJ» ✓
Award [2] for correct final answer.
Award [1 max] for −179 kJ.
Ignore an extra step to determine total enthalpy change in kJ: 179 kJ mol-1 x 5.55 mol = 993 kJ.
Award [2] for an answer in the range 990 - 993« kJ».
