Heating:

* Volume: Liquids generally expand when heated. This is because the added heat energy causes the molecules within the liquid to move faster and spread further apart.

* Mass: The mass of the liquid remains the same. Heating adds energy, not matter, so the total amount of substance doesn't change.

Cooling:

* Volume: Liquids generally contract when cooled. The molecules slow down, move closer together, and take up less space.

* Mass: The mass of the liquid remains the same. Cooling removes energy, but the total amount of substance is unchanged.

Important Notes:

* Exceptions: While most liquids follow these general rules, there are exceptions. Water is a well-known example. Water expands when it freezes (turns into ice).

* Density: Density is calculated by dividing mass by volume. As a liquid expands when heated, its density decreases. Conversely, as a liquid contracts when cooled, its density increases.

Let me know if you'd like more details on a specific liquid or aspect of this process!