Question about Evaporation at low temp.?

Question

I'm just wondering...

Evaporation is when a molecule moving fast enough departs from liquid and enters the air as gas- correct? But, molecules gain speed by picking up heat from other substances...??

If you leave a glass of water out at room temperature it evaporates.. but if its room temperature molecules don't move fast do they.. because the waters temperature isn't hot...??

can somebody explain why it evaporates. thanks =]

Answer 1

By chance, some of the molecules are moving faster than others and manage to escape.

So the more slowly moving molecules are left behind.  This is one way of looking at the fact that evaporation leads to cooling.  Wet your finger in your mouth and wave it around and you will see what I mean.