Question

Question #9ba07

Answer 1

`MnO_2(s) +3Ag^(+) + 2H_2O(l) rarr MnO_4^(-) + 3Ag(s)darr + 4H^(+)`

Are charge and mass balanced?

Explanation:

`"Oxidation: " Mn(IV) rarr Mn(VII)`

`MnO_2(s) +2H_2O(l) rarr MnO_4^(-) + 4H^(+)+3e^-` `(i)` `;E^@=-1.68V`

`"Reduction: " Mn(IV) rarr Mn(VII)`

`Ag^(+) + e^(-) rarr Ag(s)` `(ii)` `;E^@=0.80V`

`"Overall: "1xx(i)+3xx(ii)`,

`MnO_2(s) +3Ag^(+) + 2H_2O(l) rarr MnO_4^(-) + 3Ag(s)darr + 4H^(+)`
`;E^@=-0.78V`

I looked up the electrode potentials, and the reaction is NOT feasible. Reduction of `Ag^(2+)` would drive the reaction:

`Ag^(2+) + 2e^(-) rarr Ag(s)` `(iii)` `;E^@=1.99V`