PASCO TD-8557 Basic Calorimetry Set - Manual (Page 12)

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B a s i c C a l o r i m e t r y S e t
10
Experiment 4: Latent Heat of Fusion
Equipment Needed
• Calorimeter
• Thermometer
• Ice in water (at melting point)
• Warm water
Introduction
Just as steam has a higher internal energy content than water, so water has a higher internal
energy content than ice. It takes a certain amount of energy for the water molecules to
break free of the forces that hold them together in the crystalline formation of ice. This
same amount of energy is released when the water molecules come together and bond to
form the ice crystal.
In this experiment, you will measure the difference in internal energy between one gram
of ice at 0° C and one gram of water at 0° C. This difference in energy is called the latent
heat of fusion of water.
Procedure
1. Measure T
rm
, the room temperature.
2. Determine M
cal
, the mass of the empty, dry calorimeter.
3. Fill the calorimeter approximately 1/2 full of warm water about 15° C above room
temperature.
4. Measure M
cal + water
, the mass of the calorimeter and water.
5. Measure T
initial
, the initial temperature of the warm water.
6. Add small chunks of ice to the warm water, wiping the excess water from each piece
of ice immediately before adding. Add the ice slowly, stirring continuously with the
thermometer until each chunk melts.
7. When the temperature of the mixture is as much below room temperature as the warm
water was initially above room temperature and all the ice is melted, measure the final
temperature of the water (T
final
).
8. Immediately after measuring T
final
, weigh the calorimeter and water to determine
M
final
.
Suggested Additional Experiment
Repeat the above experiment, but, instead of ordinary ice, use the material which is pack-
aged in metal or plastic containers to be frozen and used in picnic coolers.
Data
T
rm
= ________________
M
cal
= ________________
M
cal + water
= ________________
T
initial
= ________________