Evaporation And Boiling

What is the Difference between EVAPORATION and BOILING?

Evaporation and boiling are both processes that change the state

of a substance from a liquid to a gas.

 

Both evaporation and boiling involve the particles of a liquid gaining enough kinetic energy so that they move fast enough to escape from the liquid and become gas particles.

 

During evaporation this only happens at the surface of a liquid and can happen at any temperature.

 

Boiling happens at a certain temperature. For a particular liquid this temperature is called the liquid’s boiling temperature.

In this case the particles can escape from all places in the liquid and

Boiling is identified with particles of gas moving upwards through the liquid.
Why does evaporation lead to cooling?

The easy way:
To change from a liquid to a gas needs energy to break the bonds. This energy is taken from the surroundings, so when some water evaporates, the rest is cooled.

Better:
Evaporation involves the fastest moving molecules near the surface escaping. Whe the faster molecules escape, the average speed of the remaining molecules goes down. Since temperature is a measure of average speed, then temperature goes down.

 

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