PASCO ET-8499 Energy Transfer Calorimeter - Manual (Page 10)

Energy Transfer Calorimeter Experiment 1: Heat of Fusion of Ice
8 ®
In this experiment, the water and the inner aluminum Calorimeter cup lose energy and cool down,
while the ice gains energy first in melting, and then in warming that melted ice-water up to the
final equilibrium temperature of the system. The water and cup undergo the same temperature
change, but the melted ice-water undergoes a different temperature change. It is assumed that the
initial temperature of the ice is 0°C.
Setup
This experiment requires a source of ice that is not crushed, preferrably small chunks of about 5
grams. Some care must be taken with the ice. Ice that is taken from the freezer will be much
colder than 0°C and cannot be used immediately straight out of the freezer. You must wait until
the ice has warmed up to 0°C and is melting. On the other hand, if the ice sits around the lab for a
hour in an icy water bath, there will be pockets of water within the ice that have already melted.
The ideal is to take a chunk of ice out of the freezer, place it on napkin, and wait until it is
melting.
Procedure
1. Measure the ambient temperature of the room.
2. Measure the mass of the inner aluminum cup from the Calorimeter. Only the inner cup
changes temperature and is part of the experiment. The outer (bigger) cup acts only as a
holder, and due to the air gap in between, helps to insulate the inner cup.
3. Prepare some water that is about 8°C above room temperature. Add about 40 g of this water
to the inner cup. Measure the combined mass of the cup and water to determine the exact
mass of the water. After the cup and water have come to equilibrium and you are ready to
start the experiment, you will want the temperature to be at least 5°C above room
temperature.
4. Measure the mass of the cup plus water, and calculate the mass of the water.
5. Assemble the Calorimeter, using the spacer to suspend the inner cup inside the bigger cup.
Put on the lid, and use the one-hole stopper in the lid to hold the thermometer.
6. Prepare about 5 grams of ice. It must be a solid chunk, not crushed. If you take the ice cube
directly from the freezer, you must wait a few minutes for it to warm up and start to melt. You
do not need to know the exact mass now, but it should be about 5 grams.
7. Check the temperature of the water again. If the water is not about 5°C above room
temperature, you can place the cup and water in a water bath to change the temperature
slightly. Wipe off any moisture on the cup before placing it back into the outer cup. Gently
swirl the cup to stir the water and wait for equilibrium before adding the ice.
8. Record the initial temperature of the water and cup to a resolution of at least 0.1°C