DP Chemistry (last assessment 2024)
Question 22N.2.hl.TZ0.3f.vi
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.2.hl.TZ0.3f.vi |
| Level | hl | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate | Question number | f.vi | Adapted from | N/A |
f.vi.
[Maximum mark: 1]
22N.2.hl.TZ0.3f.vi
Consider the following reaction:
Cu2+ (aq) + Fe (s) → Fe2+ (aq) + Cu (s)
The diagram shows an unlabelled voltaic cell for the reaction:
Cu2+ (aq) + Fe (s) → Fe2+ (aq) + Cu (s)
(f.vi)
Calculate the standard free energy change, in kJ, for the cell. Use your answer in (f)(v) and sections 1 and 2 of the data booklet.
If you did not obtain an answer in (f)(v), use 0.68 V, although this is not the correct answer.
[1]
Markscheme
«ΔG⦵ = – nF E⦵ = – 2 mol × (9.65 x 104 C mol–1) × (0.79 V) =» –152 «kJ» ✔
Accept answers in the range 150 – 153.
Examiners report
Most correctly calculated the free energy change from the cell potential, however the value of "n" (the number of electrons transferred) and converting the result to kJ, as was required by the question, created difficulties for some.
