Question

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 `:`
A. `-22.88kJ`
B. `-228.88kJ`
C. `-228.88kJ`
D. `-343.53kJ`

Answer 1

Correct Answer - B
The equation for the formation of `OH^(-)(aq)` is:
`H_(2)(g)+(1)/(2)O_(2)gtoH^(+)(aq.)+OH^(-)(aq)` ltbr. It is obtained by adding the two given equations:
`DeltaH=57.32+(-286.2)=-228.88kJ`