Question #c44c2 Chemistry Thermochemistry Enthalpy 1 Answer Ernest Z. Apr 5, 2015 #w = "-2 kJ"# Start with the definitions. #H = U + PV#, so #ΔH = ΔU + Δ(PV)# If the pressure is constant, #ΔH = ΔU + PΔV# But #w = -PΔV#, so #ΔH = ΔU – w# #w = ΔU – ΔH = "-2045 kJ – (-2043 kJ)" = "-2 kJ"# Answer link Related questions How are enthalpy changes expressed in chemical equations? How can enthalpy change be determined for an aqueous solution? How does enthalpy change with pressure? How do you calculate standard molar enthalpy of formation? Why is enthalpy a state function? Why is the enthalpy of formation of oxygen zero? Why is enthalpy a state function? Why can enthalpy not be measured directly? How does pressure affect enthalpy? How does enthalpy relate to internal energy? See all questions in Enthalpy Impact of this question 1808 views around the world You can reuse this answer Creative Commons License