How much heat is released when 75.0 g of steam at 100.0°C is cooled to ice at -15.0°C? The enthalpy of vaporization of water is 40.67 kJ/mol, the enthalpy of fusion for water is 6.01 kJ/mol, the molar heat capacity of liquid water is 75.4 J/(mol °C), and the molar heat capacity of ice is 36.4 J/(mol °C).

Question

How much heat is released when 75.0 g of steam at 100.0°C is cooled to ice at -15.0°C? The enthalpy of vaporization of water is 40.67 kJ/mol, the enthalpy of fusion for water is 6.01 kJ/mol, the molar heat capacity of liquid water is 75.4 J/(mol  °C), and the molar heat capacity of ice is 36.4 J/(mol  °C).

DrBob222 · Answer

From the last problem you know how to handle the two different kinds of heat transfer; i.e., one kind at changing T when in just one state, the second when change state. Therefore, I will leave this to you except to point out the transitions that must be made.
q1 = heat released when steam condenses.
q2 = heat released moving from 100 C to 0 c.
q3 = heat released freezing liquid water at zero C to ice at zero C.
q4 = heat released moving ice from zero to -15 C.
Total heat released = q1 + q2 + q3 + q4.

Anonymous · Answer

0.987