Question

Under what conditions ΔH = ΔU?

Answer 1

ΔH = ΔU + PΔV

1. For reactions involving solids and liquids, ΔV is negligibly small. Hence, ΔH = ΔU
2. For isochoric process, ΔV = 0. Hence, ΔH = ΔU
3. For a chemical reaction, ΔH = ΔU + Δn_sRT

In a chemical reaction, in which number of moles of gaseous reactants and products are equal Δn_s = 0 and ΔH = ΔU