Question

For which of the following reaction, ΔH = ΔU?

Options

• \[\ce{2CO_{(g)} + O_{2(g)} -> 2 CO_{2(g)}}\]

• \[\ce{H2O_{(l)} ->[\Delta] H2O_{2(g)}}\]

• \[\ce{H_{2(g)} + Br_{2(g)} -> 2 HBr_{(g)}}\]

• \[\ce{PCl_{5(g)} ->[\Delta] PCl_{3(g)} + Cl_{2(g)}}\]

Answer 1

\[\ce{H_{2(g)} + Br_{2(g)} -> 2 HBr_{(g)}}\]

Explanation:

Since, ΔH = ΔU + Δn_gRT

For the reaction,

\[\ce{H_{2(g)} + Br_{2(g)} -> 2 HBr_{(g)}}\]

Δn_g = 2 - 2 = 0

∴ ΔH = ΔU