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Old Sep 24th 2013, 10:23 AM   #1
sy416
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How much liquid water evaporated?

Water at 0 Celsius was placed in a dish inside a vessel maintained at low pressure by a vacuum pump. After a quantity of water evaporated, the remainder froze. If 9.31 g of ice at 0 Celsius was obtained, how much liquid water must have evaporated? The heat of fusion of water is 6.01 kJj/mol and its heat of vaporization is 44.9 kJ/mol at 0 Celsius.

So..

9.31 g x [1 mol / 18g ] = 0.517 mol H2O

0.517 mol x [6.01 kJ /mol] = 3.11 kJ


Now I am stuck...
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Old Sep 24th 2013, 01:17 PM   #2
bjhopper
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Originally Posted by sy416 View Post
Water at 0 Celsius was placed in a dish inside a vessel maintained at low pressure by a vacuum pump. After a quantity of water evaporated, the remainder froze. If 9.31 g of ice at 0 Celsius was obtained, how much liquid water must have evaporated? The heat of fusion of water is 6.01 kJj/mol and its heat of vaporization is 44.9 kJ/mol at 0 Celsius.

So..

9.31 g x [1 mol / 18g ] = 0.517 mol H2O

0.517 mol x [6.01 kJ /mol] = 3.11 kJ


Now I am stuck...
heat of fusion must equal heat of evaporation.Set up equation with x equal to mol water evaporated
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