Question

Sweat evaporates off your arm. Endothermic or exothermic and why?

Answer 1

Endothermic

Explanation:

Think of what happens at the molecular level -- the water molecules absorb heat, and eventually break their intermolecular forces to achieve the gas phase. Hence, the system takes in heat, which is the very definition of endothermic.

Also, just think of it practically -- the purpose behind sweating is to cool your body down. If the process didn't lead to heat being absorbed, it wouldn't do much good.

Hope that helped :)