The enthalpy of formation of `UF(g)` is `22kcal mol^(-1)` and that of `U(g)` is `128kcal mol^(-1)`.
The bond energy of the `F-F` bond is `37kcal mol^(-1)` . The bond dissociation energy of `UF(g)` is `(are):`

Options

A. `124.5 kcal mol^(-1)`
B. `131.1 kcal mol^(-1)`
C. `521 kJ mol^(-1)`
D. `623 kJ mol^(-1)`

Answer

A, C

Explanation

`U + 1/2 F_2 rarr UF " "Delta H_(f) = 22k cal//mol`
`DeltaH_(r)(UF) = DeltaH_(f) (U) + 1/2 B.D (F - F) - B.D (U -F)`
`22 + 128 + 1/2 (37.0) - 22 = 124.5 kcal//mol`
`implies 2 cal rarr 8.314 J`
`124.5 cal rarr (8.314)/2 xx 124.5 = 517.54 kJ//mol`