Assume each reaction is carried out in an open container. For which reaction will be `Delta H = Delta U` ?

Options

A. `C(s) + 2H_(2)O(g) rarr 2H_(2)(g) + CO_(2)(g)`
B. `PCl_(5)(g) rarr PCl_(3)(g) + Cl_(2)(g)`
C. `2CO(g) + O_(2)(g) rarr CO_(2)(g)`
D. `H_(2)(g) + Br_(2)(g) rarr 2HBr(g)`

Answer

D

Explanation

`Delta U = Delta E + Delta n_(g) RT`
For the reaction
`H_(2)(g) + Br_(2)(g) rarr 2HBr(g)`
`Delta n_(g) = 2 - (1 + 1) = 0`
:. `Delta H = Delta U`