How does enthalpy change with temperature?

1 Answer
Sep 30, 2015

Enthalpy will change depending on the temperature.


When we calculate enthalpy, the sum of internal energy and the product of pressure and volume, we calculate it for a specific temperature.

If you were to increase the temperature, you would also increase the energy of the molecules, meaning those molecules interact with each other at a greater rate. Thus, you have increased your internal energy. Therefore, you would also expect your enthalpy to increase (because enthalpy is internal energy+(pressure*volume)).

If you were to keep increasing the temperature, the substance might eventually undergo a phase change (for example, heat up enough water and it becomes steam). At the critical point, where the phase change occurs, you would see a decrease in temperature and enthalpy of the substance, as shown below.