How much energy (in kilojoules) is released when 12.3g of steam at 121.5degree C is condensed to give liquid water at 64.5 degree C? The heat of vaporization of liquid water is 40.67 kj/mol, and the molar heat capacity is 75.3 J/(K mol) for the liquid and 33.6 J/(K mol) for the vapor

Answer 1

The easiest way to do this is to do it in steps.
q1 = heat to move steam from 121.5 to 100.
q1 = mass x specific heat steam x delta T.

q2 = heat to condense steam at 100 C to liquid water at 100.
q2 = mass x heat vaporization.

q3 = heat to move liquid water at 100 C to liquid water at 64.5 C.
q3 = mass x specific heat water x delta T.

Total heat removed = q1 + q2 + q3.

Answer 2

34.1kJ