On the basis of the following thermochemical data `:` `(Delta_(f)G^(@)H_((aq.))^(+)=0)`
`H_(2)O_((l))rarr H_((aq.))^(+)+OH_((aq.))^(-),DeltaH=57.32kJ`
`H_(2(g))+(1)/(2)O_(2(g))rarrH_(2)O_((l)),DeltaH=-286.20kJ`
The value of enthalpy of formation of `OH^(-)` ion at `25^(@)C` is `:`

Options

A. `-22.88 kJ`
B. `-228.88 kJ`
C. `+228.88 kJ`
D. `-343.52 kJ`

Answer

B

Explanation

By adding the two given equations, we have
`H_(2(g))+(1)/(2)O_(2(g)) rarr H_((aq))^(+) +OH_((aq))^(-), Delta H =-228.88 kJ`
Here `Delta H_(f)^(@)" of "H_((aq))^(+) =0`
`therefore Delta H_(f)^(@)" of "OH^(-)=-228.88 kJ`