Answer:
This is a balanced redox reaction.
The oxidation state of arsenic (As) changes from +3 to +5, while the oxidation state of manganese (Mn) changes from +7 to +2.
To balance the equation, you need to add 5 electrons (e-) to the left side to balance the oxidation half-reaction and 10 hydrogen ions (H+) to the right side to balance the reduction half-reaction.
The balanced equation is:
5H3AsO3 + 2MnO4- + 6H+ → 5H3AsO4 + 2Mn2+ + 3H2O
Oxidation half-reaction:
5H3AsO3 → 5H3AsO4 + 5e-
Reduction half-reaction:
2MnO4- + 5e- + 6H+ → 2Mn2+ + 3H2O
Overall reaction:
5H3AsO3 + 2MnO4- + 6H+ → 5H3AsO4 + 2Mn2+ + 3H2O