ClO₂^–(aq) + Fe(s) → Fe(OH)₃(s) + ClO^–(aq)

basic environment

[ClO₂^–(aq) + 2 H⁺(aq) + 2 e^– → ClO^–(aq) + H₂O(l)] ×3

[Fe(s) + 3 H₂O(l) → Fe(OH)₃(s) + 3 H⁺(aq) + 3 e^–]× 2

sum and eliminate common species

3 ClO₂^–(aq) + 2 Fe(s) + 3 H₂O(l) → 2 Fe(OH)₃(s) + 3 ClO^–(aq)

No H⁺(aq) to worry about.