FREEZING POINT OF WATER
Name: ________________
OBJECTIVES:
In this experiment, you will
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MATERIALS
Macintosh Computers
Temperature Probe
Logger pro Software
Ring Stand
Burette Clamp
Test tube
water
400- mL beaker
10 mL graduated cylinder
ice
salt
spoon
SETUP:
FIGURE 1
PROCEDURE
1. Check all the necessary connections - especially the connection of the temperature probe to the
computer.
2. Open the file “14 Freezing Water.xmbl” as per teacher’s directions. Make sure that the computer
identifies the temperature probe.
3. Put approximately 100 mL of water and 6 - 8 ice cubes into a 400-mL beaker as shown in Figure 1.
4. Measure and put 5 mL of water into the test tube and use a burette clamp to fasten the test tube to a ring
stand. Place the Temperature Probe into the water inside the test tube.
5. When everything is ready, go to Experiment at the top menu and click Start Collection to begin data
collection. Then lower the test tube into the ice-water bath.
6. Soon after lowering the test tube, add 5 spoons of salt to the beaker and stir with a spoon. Continue to
stir the ice-water bath.
7. Another person in the group should slightly, but continuously, move the temperature probe during the
first 10 minutes of data collection. Be careful to keep the probe in, and not above, the ice as it forms.
8. Study the graph on the screen as the water freezes.
9. When 10 minutes have gone by, stop moving the probe and allow it to freeze into the ice. Continue to
stir the ice-water bath. Add more ice cubes as the original ice cubes get smaller.
10. Write at least three observations about the experiment so far.
11. When 15 minutes have passed, data collection will stop.
12. Feel the outside of the beaker and the test tube. Observe the appearance of the beaker and the test tube.
Make and record observations as the water freezes.
13. Copy the graph shown on the computer screen below. Pay attention to the numbers on the axis.
14. On the displayed graph, analyze the flat part of the curve to determine the freezing temperature of
water. Highlight and select the flat part of the graph. Click on the Statistics button from the top of the
screen. The mean temperature value for the selected data will appear in the statistics box on the
graph. This is your value for the freezing temperature of water.
Record this number as the freezing point of water: ___________
15. Put a thermometer in the salt-water bath, record its temperature: ______________
16. Do NOT attempt to remove the Temperature Probe from the ice! Remove the test tube from the water
bath and let it melt in an empty beaker. Quit the Logger Pro file and do NOT save. Rinse the beaker
and carefully move the set up to the side. Clean up your tables.
FREEZING POINT OF WATER (HW)
Name:
Due date:
1. Label the different parts of the equipment, such as the ring stand, temperature probe, burette clamp etc.
2. Define freezing: ______________________________________________________________________
3. Is freezing an endothermic (adding energy) or exothermic (removing energy) change of state? Explain.
4. What happened to the temperature of the water during freezing?
6. The outside of the beaker and test tube became cloudy. What change of state do you think caused the
beaker to become cloudy? Explain.
7. I was surprised when… (complete the sentence and explain.)
8. Phenyl Salicylate has a freezing temperature of 41.5 degrees Celsius. Sketch and label a freezing curve for
Phenyl Salicylate. Be sure to label the axis and where the freezing occurs.
9. How did the temperature of the salt-water bath compare to the ice? Give a possible explanation.