Question

For the following half-cell reactions, Eº values are also given : Mn2+ + 2H2O MnO2 + 4H+ + 2e–, Eº = – 1.23 V + 4H+ + 3e– MnO2 + 2H2O, Eº = + 1.70 V Select correct statement(s) : A Mn2+ reacts with in acid solution to form MnO2 B Mn(MnO4)2 is stable in acid solution C MnO2 disproportionates to Mn2+ and in acid solution D None is correct

Answer 1

Standard electrode potential of reaction will not change due to multiply the half-cell reactions with some numbers,

To get the main eq we have to reverse 2nd equation and add them

So E

3

=E

2

+E

1

E

3

=−1.18+(−1.51)

E

3

=−2.69V

The reaction is not possible as the ΔG will come +ve for this case and that indicates reaction is non-spontaneous.

Answer 2

Answer:

ANSWER

Standard electrode potential of reaction will not change due to multiply the half-cell reactions with some numbers,

To get the main eq we have to reverse 2nd equation and add them

So E

3

=E

2

+E

1

_______________

E

3

=−1.18+(−1.51)

________________

E

3

=−2.69V

__________________

The reaction is not possible as the ΔG will come +ve for this case and that indicates reaction is non-spontaneous