Lesson: Heat of Vaporization

In this lesson, we will learn how to relate the mass conversion between liquid and gas states to net heating and the latent heat of vaporization.

Sample Question Videos

  • 04:57
  • 03:35

Worksheet: 10 Questions • 2 Videos

Q1:

How much heat transfer is required to produce the temperature and phase changes from the initial to the final temperatures and phases?

A stage of the heating of the ice is defined to mean either a time interval in which the ice’s temperature increases while its phase does not change or a time interval in which the ice’s temperature does not change but its phase does change. How long is the third stage?

Q2:

An aluminum pan has a mass of 0.810 kg and is at a temperature of 1 1 2 . 0 C . A 0.500 kg mass of water with an initial temperature of 2 5 . 0 C is poured into the pan. If 8.00 g of the water evaporates, determine the equilibrium temperature of the pan and the water, assuming that heat loss by processes other than evaporation is negligible and that the change in mass of water due to evaporation has a negligible effect on the cooling rate of the water. Use a value of 4 1 8 4 / J k g C for the specific heat capacity of water, 2 2 3 0 J/g for the specific latent heat of vaporization of water, and 9 0 0 / J k g C for the specific heat capacity of aluminum.

Q3:

A glass cup has a mass of 80.0 g. The cup contains a 275 g mass of coffee that cools from a temperature of 7 0 . 0 C to 3 5 . 0 C . Determine how many grams of coffee must evaporate to produce this temperature change, assuming that cooling from all other processes is negligible and that the change in the mass of coffee due to evaporation negligibly affects its cooling rate. Use a value of 2 3 4 0 kJ/kg for the coffee’s heat of vaporization, 4 1 8 4 / J k g C for the specific heat capacity of coffee, and 8 4 0 / J k g C for the specific heat capacity of glass.

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