This is the amount of energy that must be added to a liquid to overcome the intermolecular forces holding it together and allow it to transform into a gas.

Here are some key points to remember:

* Heat of vaporization is a specific value for each substance. Different liquids require different amounts of energy to vaporize.

* It's an endothermic process. This means that energy is absorbed by the substance during the phase change.

* The opposite process (condensation) releases the same amount of energy.

Let me know if you have any other questions!