How much heat would have to be added to the 2000 g of water to completely vaporize it (turn all 2000 g of water at 100 °c to 2000 g of water vapor at 100 °c)? the heat of vaporization of water, dhvap = 40.7 kj/mol.

4520 kJ

Explanation:

To make a substance transition phases an energy must be applied, this is know as the latent heat.

Water has a latent heat of 40.7 KJ/mol to turn into vapor.

The molecule of water has a molecular weight of 18. This means that a mol of water weights 18 grams.

With this we can convert the latent heat to use grams instead of mols

Now, the heat needed to vaporize water is simply:

Q = m * DHvap = 2000 g * 2.26 kJ/g = 4520 kJ

the answer is b, have negligible mass

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