to
begin data collection. Then lower the test tube into the ice-water bath. Phase Change Activity with Vernier
PROCEDURE
Part I Freezing
1. Fill a 400 mL beaker 1/3 full with ice, then add 100 mL of water.
2. Put 5 mL of water into a test tube and use a utility clamp to fasten the test tube to a ring stand. The test tube should be clamped above the water bath. Place the Temperature Probe into the water inside the test tube.
3. Connect the Temperature Probe to the computer interface. Prepare the computer for data collection by opening the file “03 Freezing and Melting” from the Physical Science w Computers folder.
4. When everything is ready, click
to
begin data collection. Then lower the test tube into the ice-water bath.
5. 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 during Part I.
6. Slightly, but continuously, move the probe during the first 10 minutes of Part I. Be careful to keep the probe in, and not above, the ice as it forms. When 10 minutes have gone by, stop moving the probe and allow it to freeze into the ice. Add more ice cubes to the ice-water bath as the original ice cubes get smaller.
7. When 15 minutes have passed, data collection will stop. Keep the test tube submerged in the ice-water bath until Step 10.
8. On the displayed graph, analyze the flat part of the curve to determine the freezing temperature of water:
• Move the mouse pointer to the beginning of the graph’s flat part. Press the mouse button and hold it down as you drag across the flat part to select it.
•
Click on the Statistics button,
.
The mean temperature value for the selected data is listed in the statistics box
on the graph. Record this value as the freezing temperature in your data table.
• Remove the statistics box.
Part II Melting
9. Store your data by choosing Store Latest Run from
the Experiment menu. This stores the data so it can be used later. To hide the
curve of your first data run, click the Temperature vertical-axis label of the
graph, click on More, and uncheck Run 1 Temperature. Click
.
10. Click
to
begin data collection. Then raise the test tube and fasten it in a position
above the ice-water bath. Do not move the Temperature Probe during Part II.
11. Dispose of the ice water as directed by your teacher. Obtain 250 mL of warm tap water in the beaker. When 12 minutes have passed, lower the test tube and its contents into this warm‑water bath on a hotplate turned to level 2.
12. When 15 minutes have passed, data collection will stop.
13. On the displayed graph, analyze the flat part of the curve to determine the melting temperature of water:
• Move the mouse pointer to the beginning of the graph’s flat part. Press the mouse button and hold it down as you drag across the flat part to select it.
•
Click the Statistics button, .
The mean temperature value for the selected data is listed in the statistics box
on the graph. Record this value as the melting temperature in your data table.
• To remove the statistics box, click on the upper-right corner of the box.
14. Print a graph of temperature vs. time showing both data runs:
•
Click the Temperature vertical-axis label of the graph. To display both
temperature runs, click on More, and check the Run 1 and Latest Temperature
boxes. Click .
• Label both curves by choosing Text Annotation from the Insert menu, and typing “Freezing Curve” (or “Melting Curve”) in the edit box. Then drag each box and its arrow to clearly identify each curve.
• Print copies of the graph as directed by your teacher.
Part II Boiling
15. Store your
data by choosing Store Latest Run from the Experiment menu. This stores the data
so it can be used later. To hide the curve of your first data run, click the
Temperature vertical-axis label of the graph, click on More, and uncheck Run 1
Temperature. Click .
16. Turned
level of the hotplate to 5. Click to
begin data collection. After 5 minutes, turn the hotplate up to level 8, and
then 5 minutes later up to 10.
17. When 15 minutes have passed, data collection will stop.
18. On the displayed graph, analyze the flat part of the curve to determine the boiling temperature of water:
• Move the mouse pointer to the beginning of the graph’s flat part. Press the mouse button and hold it down as you drag across the flat part to select it.
•
Click the Statistics button, .
The mean temperature value for the selected data is listed in the statistics box
on the graph. Record this value as the boiling temperature in your data table.
• To remove the statistics box, click on the upper-right corner of the box.