Ethalpies of solution of `BaCI_(2)(s)` and `BaCI_(2).2H_(2)O(s)` are `-20.0kJ mol^(-1)` and `8.0 kJ mol^(-1)`, respectively. Calculate `Delta_(hyd)H^(Theta)` of `BaCI_(2)` to `BaCI_(2).2H_(2)O`.

Explanation

Hydration of `BaCI_(2)` is given as
`BaCI_(2)(s)rarr 2H_(2)O(l)rarr BaCI_(2).2H_(2)O(aq),DeltaH^(Theta) = ?`
Ethalpies of solution are
a. `BaCI_(2)(s) +aq +2H_(2)O(l) rarr BaCI_(2),2H_(2)O(aq),DeltaH^(Theta) =- 20.0 kJ`
b. `BaCI_(2).2H_(2)(s)aq rarr BaCI_(2).2H_(2)O(aq),DeltaH^(Theta) = 8.0 kJ`
Subtract equation (ii) from (i), we get
`BaCI_(2)(s) +2H_(2)O(l)rarr BaCI_(2).2H_(2)O(s),DeltaH^(Theta) =- 20.0 - 8.0 =- 28.0 kJ`