Asample of water at 100°c is converted to steam after absorbing 820 kj of heat. how grams of h2o are contained in the sample? assume that the molar heat of vaporization of water is 41 kj/mol.

Since water is already at 100°C all the energy is used to evaporate it. 
Now we can calculate how many mols of water are evaporated with 820kJ.

We calculated that we got 20 mols of water evaporated. Now, all we have to do is find how many grams is a mol of water. Molar mass of water is 20.16 g/mol.
The final answer is:

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