Why is acetone so cold?

Question

I have a summer job as a custodian and one cleaner I use is called Goof Off, which is pretty much just acetone. Another is a disinfectant which is mostly water. How come whenever I put the acetone on my rag, it is always colder than when I use another cleaner or plain water? It also seems to retain its cold properties longer than water does too. Both cleaners are left in the open so they are both the same temperature. If you have acetone at home, try it yourself to see what I am talking about.

Answer 1

Acetone is a very volatile solvent, meaning that it evaporates quickly. So it's not that acetone is colder per se, but because evaporation is an endothermic phenomenon (endothermic meaning that it requires energy to happen), the acetone molecules absorb heat in order to evaporate. The heat is absorbed from whatever surface the acetone molecules are found on, and as they take heat from that surface and evaporate, the surface (your gloves, skin, etc), feels cold because it's lost energy in the form of heat.