Physics

5.6 - Evaporation

2 min

note 1 of 2

Evaporation

Evaporation is when particles escape from the surface of a liquid and become gas particles.
Unlike boiling, evaporation:
- Happens only at the surface, with no bubbles forming.
- Can happen at temperatures below the boiling point of the substance.

Particles in a liquid move at different speeds, so some have more energy in their kinetic energy stores than others.
A particle near the surface can escape if:
- It is moving in the right direction (towards the surface).
- It has enough energy in its kinetic energy store to overcome the attractive forces holding it in the liquid.

note 2 of 2

The particles that escape from the surface are the ones with the most energy in their kinetic energy stores.
When these high-energy particles leave, the average energy in the kinetic energy stores of the remaining particles falls.
A lower average kinetic energy means a lower temperature, so the remaining liquid cools down.

key terms

TermDefinition

EvaporationThe process where particles escape from the surface of a liquid and become a gas.

end of notes

Evaporation

Evaporation is when particles escape from the surface of a liquid and become gas particles.

Unlike boiling, evaporation:

How particles escape

Particles in a liquid move at different speeds, so some have more energy in their kinetic energy stores than others.

A particle near the surface can escape if:

It is moving in the right direction (towards the surface).
It has enough energy in its kinetic energy store to overcome the attractive forces holding it in the liquid.

Evaporation cools the liquid left behind

The particles that escape from the surface are the ones with the most energy in their kinetic energy stores.

When these high-energy particles leave, the average energy in the kinetic energy stores of the remaining particles falls.

A lower average kinetic energy means a lower temperature, so the remaining liquid cools down.