[lilywhitedaisy]

I am dying here! I am really struggling with how to set up word problems with Mastering Chemistry. I don't know how to figure out the steps in this problem:

How many kilocalories are needed to vaporize 18.0  of H2O?

[Fluorine]

How many kilocalories are needed to vaporize 18.0  of H2O?

What is the unit for 18.0; moles, milligrams, liters, etc.? Without it I don't see how it's possible to solve. After applying the appropriate unit given in the question try solving it again.

Hint:
1) 40.65 kilojoules/mol is the heat of vaporization for water.
2) 1cal equals 4.1868 joules.