Question

Why is enthalpy change approximately equal to internal energy for liquid and solid?

Answer 1

Answer:

Because the reaction is run at constant pressure, the change in the enthalpy that occurs during the reaction is equal to the change in the internal energy of the system plus the product of the constant pressure times the change in the volume of the system.

Answer 2

because the reaction occur at constant pressure so change in entholpy will be equal to change in internal and plus product of pressure and volume.