Hence (because 1 Pa m3 = 1 J), ΔHm − ΔUm = −0.28 J mol−1, which is only 0.1 per
cent of the value of ΔUm. We see that it is usually justifiable to ignore the difference
between the molar enthalpy and internal energy of condensed phases, except at
very high pressures, when pΔVm is no longer negligible.