Ethyl alcohol has a heat of vaporization of 850. J/g. What mass of ethyl alcohol can be boiled using 15000 J of energy?

The amount of heat, H, needed to boil off certain mass, m, of the substance is given by the equation,

H = mHv

where Hv is the heat of vaporization. Manipulating the equation, the mass is calculated by,

m = H/Hv

Substituting the known values,

m = 15000 J / (850 J/g) = 17.65 g

Thus, the mass of ethyl alcohol is approximately 17.65 g.