Question

Which among the following reactions exhibits $\Delta H=\Delta U$?

• A. $H_{2(g)}+Br_{2(g)}\rightarrow2HBr_{(g)}$
• B. $2CO_{(g)}+O_{2(g)}\rightarrow2CO_{2(g)}$
• C. $PCl_{5(g)}\rightarrow PCl_{3(g)}+Cl_{2(g)}$
• D. $C_{(s)}+2H_{2}O_{(g)}\rightarrow2H_{2(g)}+CO_{2(g)}$

Hint:

Logic Tip: Whenever you are asked to relate $\Delta H$ and $\Delta U$ for a reaction, solely focus on counting the coefficients of the species marked with a $(g)$ state symbol. If the sum of gas coefficients on both sides matches, the enthalpy change equals the internal energy change.

Answer 1

The Correct Option is A