Question

# Under which of the following conditions is the relation, Δ H = Δ U + PΔ V valid for a closed system?

A

Constant pressure

B

Constant temperature

C

Constant temperature and pressure

D

Constant temperature, pressure and composition

Solution

## The correct option is D Constant temperature and pressure We know that H = U + PV Δ H = Δ U + Δ PV Δ H = ΔU+PΔV+VΔP At constant pressure Δ H = Δ U + PΔV But PΔV = Δng RT Δ H = Δ U + Δng RT At constant temperature ∴ At constant pressure & temperature

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