Which of the following reaction has `Delta H = Delta U`?

Options

A. `2 SO_(2) (g) + O_(2) (g) rarr 2 SO_(2) (g)`
B. `H_(2) (g) + Cl_(2) (g) rarr 2 HCl (g)`
C. `2 NH_(4) NO_(3) (s) rarr 2 N_(2) (g) + 4 H_(2) O (g) + O_(2) (g)`
D. `C_(2) H_(5) OH (l) + 3 O_(2) (g) rarr 2 CO_(2) (g) + 3 H_(2) O (l)`

Answer

B

Explanation

For any reaction.
`Delta H = Delta U + Delta n_(g) Rt`
`Delta H = Delta U` only when `Delta n_(g) = 0`, this is true for the second reaction.
`Delta n = [ 2 mol HCl (G)] - [1 mol H_(2) (g) + 1 mol Cl_(2) (g)]`
` 2 mol - 2 mol = 0 mol`