Write a balanced half-reaction for the reduction of bismuth oxide ion to bismuth ion in acidic aqueous solution. be sure to add physical state symbols where appropriate.

BiO₃⁻ → Bi³⁺
+5           +3
Balance oxidation state:
BiO₃⁻ + 2 e⁻ → Bi³⁺ 
Balancing oxygen by adding water and balance H
BiO₃⁻ + 6 H⁺ + 2 e⁻ → Bi³⁺ + 3 H₂O
balance charge:
BiO₃⁻ + 6 H⁺ + 2 e⁻ → Bi³⁺ + 3 H₂O
      + 3                               + 3
Final:
BiO₃⁻ + 6 H⁺ + 2 e⁻ → Bi³⁺ + 3 H₂O