Why is an external emf of more than `2.2V` required for the extraction of `CI_(2)` from brine?

Explanation

For the reaction, ` 2 Cl ^(-) (aq) + 2 H_ 2 O (l) to 2 O H ^(-) (aq) + H _ 2 ((g ) + Cl _ 2 (g ) `
` Delta G^(@) ` for this reaction is ` + 422 kJ `
Using the equation, ` Delta G^(@) = -nFE^(@) `, the value of ` E ^(@) ` comes out to be ` - 2.2 V ` ,i.e,
` 422 xx 1000 J = - 2 xx 96500 xx E^(@) or E ^(@) = - 2*18 V or - 2*2 V `
Therefore, extraction of ` Cl _ 2 ` from brine will require an external emf of greater than ` 2 * 2 ` V.