Calculate the enthalpy change when one mole of `HCl(g)` is dissolved in a very large amount of water at `25^(@)C`. The change in state is: `HCl(g)+arrarrH^(+)(aq)+Cl^(-)(aq)`
Given: `Delta_(f)H(HCl, g) -92 KJ mol^(-1)` and `Delta_(f)H^(@)(Cl^(-),aq)= -167 KJ mol^(-1)`

Explanation

For the reaction, `HCl(g)+aq rarrH^(+)(aq)+Cl^(-)(aq)`
we have `Delta H^(@)+Delta_(f)H^(@)(Cl^(-),aq)-Delta_(f)H^(@)(HCl,g)`
`Delta H^(@)=[-167-(-92)]KJ mol^(-1)= -75KJ mol^(-1)`