The change in enthalpy and the change in internal energy of a system always will be equal when ________

Question

Quizplus · Accepted Answer

The change in enthalpy (ΔH) and the change in internal energy (ΔU) of a system will be equal when the volume is constant. This is because enthalpy is defined as H = U + PV, where H is enthalpy, U is internal energy, P is pressure, and V is volume. When volume is constant, there is no work done by expansion or compression (W = PΔV = 0), so the only energy change in the system is due to changes in internal energy, making ΔH = ΔU.

The Change in Enthalpy and the Change in Internal Energy