Water becomes steam at 100 celcius degrees and how this happens?

Question

Water becomes steam at 100 celcius degrees and how this happens? I forgot all physics.

If you put some water on floor and after sometimes, it evaporates. how it happens? How can water evaporate at room temperature. Thanks!

Answer 1

When you heat up the water, you give all the molecules enough energy to break their bonds with the other molecules and they become steam (i.e. gaseous phase).

Evaporation is a little different. Temperature is only an expression of the average amount of kinetic energy each molecule has. So in a body of water at room temperature, some molecules are moving slowly and other molecules are moving very quickly. If a fast-moving molecule hits the surface, it can have enough energy to break free and escape the puddle; it is now a gaseous molecule.

Since in evaporation it is the fast-moving molecules with more than the average energy that are lost to the environment, evaporation has a cooling effect. This is why we sweat when we are hot; as it evaporates it cools us down. The same principle is used in evaporative air conditioners.