Balance ionic equations (10分)

1)
Half equation of reduction :
MnO4⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H2O ......(*)

Half equation of oxidation :
AsO3³⁻ + H2O → AsO4³⁻ + 2H⁺ + 2e⁻ ...... (#)

(*)x2 + (#)x5, and cancel 10e⁻, 5H2O and 10H⁺ on the both sides :
2MnO4⁻ + 5AsO3³⁻ + 6H⁺ → 2Mn²⁺+ 5AsO4³⁻ + 3H2O


2)
Half equation of reduction :
Cr2O7²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H2O ......(*)

Half equation of oxidation :
SO3²⁻ + H2O → SO4²⁻ + 2H⁺ + 2e⁻ ...... (#)

(*) + (%)x3, and cancel 6e⁻, 6H⁺ and 3H2O on theboth sides :
Cr2O7²⁻ + 3SO3²⁻ + 8H⁺ → 2Cr³⁺ + 3SO4²⁻ + 4H2O