Answer to Question #163337 in General Chemistry for mike

Question

Balance the following half-equations

(i). MnO4–(aq)     →     MnO2(s)

(ii). SO42-(aq)     →     SO32-(aq)

(iii). AsH3(s)    →    H3AsO3(s)

Answer 1

1) MnO₄^- + 4H⁺ + 3e^- $\to$ MnO₂ + 2H₂O

2) SO$_4^{2-}$ (aq) + 2H⁺ + 2e^- $\to$ SO$_3^{2-}$ + H₂O

3) AsH₃ (s) + 3H₂O $\to$ H₃AsO₃ + 6H⁺ + 6e^-