Evaporation

Chapter 3, Topic 5

In Progress

Chapter Progress

0% Complete

Molecules of a liquid have different kinetic energies.
When they constantly collide with each other, energy is being transferred.
At the surface of the liquid, the most energetic molecules can overcome the downward attractive forces of other liquid molecules and the atmospheric pressure to escape from the surface of the liquid, hence evaporation occurs.
As the less energetic molecules are left behind, the average kinetic energy of the molecules in the liquid decreases, hence the temperature of the liquid decreases.

Boiling	Evaporation
Occurs only at boiling point.	Occurs at any temperature
Relatively fast	Relatively slow
Takes place throughout the liquid	Takes place only at the surface
Temperature remains constant	Temperature usually decreases
Bubbles are formed in the liquid	No bubbles are formed in the liquid
External thermal energy source needed	External thermal energy source not needed

[O] Pure Chemistry Smart Guides