How much heat is removed from the skin by the evaporation of 190 g (about 1/2 cup) of isopropyl alcohol?

The amount of heat removed from the skin is equal to the energy needed by the alcohol to evaporate, which is known as the latent heat of vaporization.

So, you need to know and use the specific latent heat of vaporization of the isopropyl alcohol.

The specific latent heat of vaporization dependes on temperature, but you can use the value of 159 cal / g, which is found in similar problems.

So, now you just need to multiply this specific heat by the amount of alcohol to find the total heat:

Total heat = 190 g * 159 cal / g = 30,210 cal.

Depending on the units you need you likely will have to make a conversion. For example, if you want it in joules you have to diviide by 4.18 cal/joule.

It’s the energy source of stars