Redox Reactions

Chlorine undergoes disproportionation in alkaline medium as shown below : aCl2(g) + bOH-(aq) cClO-(aq) + dCl-(aq) + eH2O(l) The values of a, b, c and d in a balanced redox reaction are respectively :

1. 3, 4, 4 and 2
2. 1, 2, 1 and 1
3. 2, 4, 1 and 3
4. 2, 2, 1 and 3

Answer

(2) 1, 2, 1 and 1

Solution

Cl: 0 → +1 in ClO- (loss of 1 e) and 0 → −1 in Cl- (gain of 1 e)

⇒ electrons lost = electrons gained ⇒ ClO- : Cl- = 1 : 1

Balancing O and H with OH- / H2O:

Cl2 + 2OH- ClO- + Cl- + H2O

∴ a = 1, b = 2, c = 1, d = 1

Answer: (2)