Question 22M.2.hl.TZ2.a(ii)
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.2.hl.TZ2.a(ii) |
| Level | hl | Paper | 2 | Time zone | TZ2 |
| Command term | Determine, Justify | Question number | a(ii) | Adapted from | N/A |
Standard electrode potential values, E⦵, can be used to predict spontaneity.
Determine, giving a reason, if iodine will also oxidize iron(II).
[1]
«2Fe2+ (aq) + 2 (s) → 2Fe3+ (aq) + 2– (aq) »
no/non-spontaneous AND «= 0.54 – 0.77 »= –0.23 «V»/
OR
no AND reduction potential of 2 lower «than Fe3+ »/ 0.54 <0.77 ✔
Accept “standard electrode potential of 2 lower /less positive than iron”.
Only 10% were able to correctly justify the feasibility of the reaction with I2; the MS showed the best answer using the E(v) values but also allowed simpler explanations referring to E0 of iron; even then many candidates wrote Fe+2 instead of Fe+3, understandably perhaps as this was mentioned in the question. However, it also revealed some difficulty in using and understanding data from the E0 table in the data booklet.
