Q.

Given below are half-cell reactions:

MnO4-+8H++5e-Mn2++4H2O ; EMn2+/MnO4-=-1.510 V

12O2+2H++2e-H2O ; EO2/H2O=+1.223 V

Will the permanganate ion, MnO4- liberate O2 from water in the presence of an acid             [2022]

1 Yes, because Ecell=+0.287 V  
2 No, because Ecell=-0.287 V  
3 Yes, because Ecell=+2.733 V  
4 No, because Ecell=-2.733 V  

Ans.

(1)

Ecell=Ecathode-Eanode =+1.510-1.223=+0.287 V

As Ecell is positive, hence the reaction is feasible.