Question

A 250 gram sample of water at the boiling point had 45.0 kj of heat added. how many grams of water were vaporized? heat of vaporization for water is 40.6 kj/mole.

Answer 1

You have 45 kJ of heat added and for every 40.6 kJ added, one mole is able to be vaporized. Find how many moles you can vaporize.

45 kJ / 40.6 kJ = 1.1 moles

Water is roughly 18 g per mole so 1.1 moles x 18 g per mol = 19.95 grams vaporized

Hope I helped!