Iron (III) catalyses the reaction between iodide and persulphate ions, in which Choose the most appropriate answer from the options given below:
- B and C only
- A only
- A and D only
- B only
Answer
(3) A and D only
Solution
Step 1: Fe3+ oxidises I- to I2, so A is correct
2Fe3+ + 2I- 2Fe2+ + I2
Step 2: Fe2+ reduces S2O82- and Fe(III) is regenerated, so D is correct
2Fe2+ + S2O82- 2Fe3+ + 2SO42-
B and C are wrong: S2O82- is itself an oxidant and I- cannot be reduced further.
Hence A and D only.
Answer: (3)