1. The problem statement, all variables and given/known data Enthalpy of formation of a mole of atomic hydrogen = 218kJ. Enthalpy changes when a mole of atomic hydrogen is formed by dissociating half a mole of molecular hydrogen. Calculate ΔU of the process of molecular hydrogen dissociation. 2. Relevant equations ΔH = ΔU + Δ(PV) PV=nRT 3. The attempt at a solution ΔU = ΔH - Δ(PV) ΔU = ΔH - Δ(nRT) ΔU = 218kJ - (1/2 mol)(8.31 J/Kmol)(298K) ΔU = 216kJ I really don't think my answer is correct.