The heat of vaporization of water at 100°C is 40.66 kJ/mol.Calculate the quantity of heat that is absorbed/released when 9.00 g of steam condenses to liquid water at 100°C.
A)20.3 kJ of heat are absorbed.
B)20.3 kJ of heat are released.
C)81.3 kJ of heat are absorbed.
D)81.3 kJ of heat are released.

Question

Quizplus · Accepted Answer

The heat of vaporization is the energy required to convert liquid to gas, and the same amount is released when gas condenses to liquid. First, convert 9.00 g of steam to moles (9.00 g / 18.02 g/mol = 0.499 moles). Then, multiply by the heat of vaporization (0.499 moles * 40.66 kJ/mol = 20.3 kJ). Since condensation releases heat, 20.3 kJ of heat are released.

The Heat of Vaporization of Water at 100°C Is 40