Evaporation：Evaporation

You wouldn’t know it, but this water contains about ten tablespoons of salt. The soluble salt has dissolved into the water to make a salty solution. Luckily, I know how to get my salt back, using a process called evaporation!

See, in this salt solution there are water molecules and salt particles all mixed together. The particles in a liquid are constantly jiggling around, and the warmer the liquid is, the faster they’ll move.

Sometimes, near the top of the glass, the water particles will be going fast enough to escape into the air.

This is evaporation, when a liquid changes state to become a gas.

As weve just seen, the rate of evaporation can be increased by heating the solution. So, if I left some of the salt solution on a sunny windowsill, the heat from the sun would warm up the water and slowly it would evaporate into the air.

But if I didn’t want to wait that long, I could speed up the evaporation even more by heating it.

I’ll put the salt so...