According to first law of thermodynamics, q= ΔU + PΔV If the process is carried out at constant volume , ΔV=0 qv = ΔU where v indicates constant volume. Internal energy change is the heat absorbed or evolved at constant volume. ΔU is a state function, therefore qv ,is also a state function. If the process is carried out at constant pressure, the work of … [Read more...] about Enthalpy