Question #9ba07

1 Answer
Oct 18, 2016

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