Explanation:
In system enclosed so as to prevent the mass transfer, for such processes, at constant pressure, heat absorbed/released equals change in enthalpy.
If there is a closed system , which means that there is no exchange of heat and energy, there will be no heat absorbed/ gained. So, the enthalpy of the system is only the internal energy possessed by the system.
On the other hand, if there is change in volume at constant pressure in the system , the enthalpy is equal to the internal energy plus the product of pressure and change in volume.
