Question

For a reaction involving condensed phases, $\Delta H=\Delta U$.

• A. true
• B. false
• C. insufficient data
• D. none

Answer 1

Answer: (A)

true

The relationship between the enthalpy change and the change in internal energy is
$\Delta H=\Delta U+P\Delta V$.
For condensed phases, $\Delta V=0$. Hence, $P\Delta V=0$
Thus, for a reaction involving condensed phases, $\Delta H=\Delta U$.