Question

the enthalpy of dissolution of `BaCl _(2) (s) and BaCl_(2). 2H_(2)O(s) are - 20 . 6 and 8.8 kJ // mol ` respectively. The enthalpy of hydration for
`BaCl_(2)(s) + 2H_(2)O to BaCl_(2) . 2H_(2)O(s)` is
A. 29. 4 kJ
B. `-29 . 4 kJ`
C. `-11.8 kJ`
D. 38.2 kJ

Answer 1

Correct Answer - b
`BaCl_(2)(s)+(aq) to BaCl_(2)(aq) , DeltaH =-20.6 kJ`
`BaCl_(2). 2H_(2)O(s)+(aq) to BaCl_(2)(aq),DeltaH=+8.8 kJ` ltbr gt Eq.(i) can be split as
`BaCl_(2)(S)+2H_(2)O(l)to BaCl_(2).2H_(2)O(s),DeltaH=H_(1)`
`BaCl_(2).2H_(2)O(s)+aqto BaCl_(2)(aq),`
`DeltaH=H_(1)+H_(2)+ =-20.6, H_(1) = 8.8 kJ`
` H_(2)=-20.6-8.8 =-29.4 kJ`