Question

During the evaporation of a liquid –

• A. The temperature of the liquid will rise.
• B. The temperature of the liquid will fall.
• C. May rise or fall depending on the nature.
• D. The temperature remains unaffected.

Answer 1

The correct option is B

The temperature of the liquid will fall.

Evaporation is the process where some molecules of a liquid at the surface are able to break away from the surrounding liquid molecules. This means that it becomes a gas.

Now breaking free requires some energy. Just like you need to use a lot of energy to break a brick. When a molecule at the surface gains enough energy it breaks away. Where does this energy come from?

It comes from the liquid itself! When this molecule breaks away, the liquid as a whole loses some energy. This is why we see that the temperature drops.

Note: Clay pots and coolers work on this principle.