rubbing alcohol?

Question

2 questions:
1.why does yor hand feel cool when the rubbing alcohol evaporated?
2. Why do humans sweat?

Answer 1

1) Heat - Cool are really a measure (reflection?) of the average kinetic energy of the molecules. In evaporation the higher energy molecules "jump off" first and the lower energy (cooler) molecules are left behind. The energy came from your hand. Your hand feels cooler because it has given-up heat energy.
2) Sweating is a rather unattractive form of temperature regulation. We get over-heated, we sweat, the sweat evaporates, evaporation is a cooling process... see 1), above.