An external emf of 2.2 V is required for the manufacture of `Cl_(2)` from brine - why ?

Explanation

`2Cl^(-)(aq)+2H_(2)O(l)rarr2OH^(-)(aq)+H_(2)(g)+Cl_(2)(g).`
`DeltaG^(@)` of this reaction is `+422kJ`. Now, from the equation `DeltaG^(@)=-nFE^(@)`, we get, `E^(@)=-2.2V`. For this reason, the manufacture of chlorine from brine requires an external emf more than 2.2V.