The standard electrode potentials `(E^(@)) " for " Ocl^(-)//Cl^(-) " and " Cl^(-)//(1)/(2) Cl_(2)` respectively are 0.94 V and `-1.36 V`. The `E^(@)` value for `Ocl^(-)// (1)/(2) Cl^(2)` will be:

Options

A. `-0.42 V `
B. `0.52 V `
C. `-2.20 V `
D. `1.04` V

Answer

B

Explanation

The given half cell reactions may be written as
(i) `O Cl^(-) + H_(2)O + 2 e^(-) to Cl^(-) + 2 OH^(-) , E_(1) ^(@) = 0.94` V
(ii) `Cl^(-) to (1)/(2) Cl_(2) + e^(-) , E_(2)^(@) = -13.6` V
(iii) `O Cl^(-) + H_(2)O + e^(-) to (1)/(2) Cl_(2) + 2 OH^(-) , E_(3)^(@) = `?
Eqn. (iii) obtained by adding eqns(i) and (ii) .
Hence , their free energies , `(DeltaG^(@) = -n FE^(@))`
`DeltaG_(3)^(@) = DeltaG_(1)^(@) + Delta G_(2)^(@) - 1 xx F xx E_(3)^(@) = -2 xx F xx (0.94) - 1 xx F (-1.36) or E_(3)^(@) = 2 xx 0.94 - 1.36 = 0.52` V