posted by michelle on .
is the molar mass value of a volatile liquid, such as ethanol, high or small?
Usually small, but there are exceptions. The ability to be volatile means that the attractive forces between molecules in the liquid and vapor have to be small, so non polar molecules are the rule. Also, to get motion to escape the surface of the liquid, thermal energy can move smaller masses faster (KE= 1/2 mass*velocity^2). Lighter molecules can escape easier.