EXERCISE 2


As mentioned in Exercise 1 above, liquid water has a heat capacity of 1 calorie
per gram per degree K.

(a) The heat of fusion for water is 80 calories per gram.  If I have one liter of
liquid water at 20 deg C, and want to make the water into ice cubes at 0 deg C
(the freezing point of water at Earth's surface), how much heat energy will my
freezer have to take out of that water?  Express your answer in Joules.

(b) The heat of vaporization for water is 540 calories per gram.  If I have one
liter of liquid water at 20 deg C, and want to make it all into steam at 100 deg
C (the boiling point of water at Earth's surface), how much heat energy will my
stove have to put into that water?  Express your answer in Joules.

(c) What cools beverages more effectively, ice cubes at 0 deg C or cold water at
0 deg C?  What cooks food more effectively, hot water at 100 deg C or steam at
100 deg C?  Explain your answers.