NEETChemistryd and f Block Elements
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Iron(III) acts as a catalyst in the reaction between iodide ion and persulphate ion. Reason (R) : Fe ³⁺ catalyses the reaction by first oxidising persulphate ion to sulphate ion. In the light of the above statements, choose the most appropriate answer from the options given below :
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A).
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A).
- C(A) is correct but (R) is not correct.
- D(A) is not correct but (R) is correct.
Correct answer
C. (A) is correct but (R) is not correct.
Step-by-step solution
Assertion (A) is correct. Iron(III) ions ( Fe ³⁺ ) act as a catalyst in the reaction between iodide ion ( I ⁻ ) and persulphate ion ( S ₂ O ₈²⁻ ). Reason (R) is incorrect. In this catalytic cycle, Fe ³⁺ does not oxidise persulphate ion. Instead, Fe ³⁺ first oxidises iodide ion to iodine and gets reduced to Fe ²⁺ . The Fe ²⁺ ion is then oxidised back to Fe ³⁺ by the persulphate ion, which itself gets reduced to sulphate ion. The reactions involved are: 2 Fe ³⁺ + 2 I ⁻ 2 Fe ²⁺ + I ₂ 2 Fe ²⁺ + S ₂ O ₈²⁻ 2 Fe ³⁺ + 2 SO