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Revised: Jan. 22, 2002
EXPERIMENT 3:
AN EXPERIMENT WITH ICE CUBES AND WATER
Purpose
To get students to understand the relationship between heat and temperature.
Equipment needed
two 2-liter soda bottles
two temperature probes and a computer to read the data or two thermometers
three or more ice cubes (all about the same size)
a stirring rod
Procedure
Place 1.5 liters of hot water (at about 100˚F) in each bottle. Place
one temperature probe (or thermometer) in each. Clip the probe wires to
the bottle with a rubber band so that they stay in place.
Stir the water and let the temperature readings stabilize.
a. After the readings have stabilized, record
the two temperature readings.
b. Put one ice cube in one of the jars, and stir
the water until the cube has entirely melted. Keep stirring the water
in the other jar also.
c. Record the water temperature in the two jars.
d. Repeat b and c for as many ice cubes as you
wish, recording the temperatures in the two jars each time.
Calculate the temperature differences between the two jars in step c
for each ice cube that you have added in b above. Since each ice cube
requires the same amount of heat to melt it (they are all the same size
and temperature), and since that heat comes from the water in the bottle,
we expect that the temperature drop with each ice cube should be the same
as all the others. Actually, the ice cubes aren’t exactly the same
size, so the temperature drop will show some variation; also, each ice
cube adds volume to the bottle that slightly reduces the effect of newly-added
ice cubes. As you add more and more ice cubes, the temperature reduction
as each melts is slightly less.
You may notice that the water temperature in both jars keeps dropping
(even in the one with no added ice cubes). That is because both jars are
losing heat to the air in the room. That is the reason for the two jars;
the jar with no ice cubes acts as a reference to correct for heat loss
to the room.
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