ï temperature sensor

ï base and support rod

ï beaker, 400 mL

ï beaker, 50 mL

ï buret clamp

ï graduated cylinder, 10 mL

ï stirring rod

ï test tube

ï watch or clock

ï apron and safety goggles

ï salt

ï water

Follow all safety directives given by your teacher.

2. Connect the DIN plug of the temperature sensor into Analog Channel A of the interface.

3. Open the Science Workshop file titled as shown;

ï Note: For quick reference, see the Experiment Notes window. To bring a display to the top, click on its window or select the name of the display from the list at the end of the Display menu. Change the Experiment Setup window by clicking on the "Zoom" box or the Restore button in the upper right hand corner of that window.

4. The "Sampling OptionsÖ" for this experiment are: Periodic Samples = Slow at one measurement per 30 seconds and Stop Condition = Time at 900 seconds.

5. The vertical axis of the Graph is scaled from -20 to 30 C.

PART II: Sensor Calibration and Equipment Setup

ï You do not need to calibrate the temperature sensor. The temperature sensor produces a voltage that is proportional to temperature (10 mV = 1.0 Celsius). The default calibration is 110.000 C = 1.100 V and -10.000 C = -0.100 V. If you would like to calibrate the temperature sensor, please refer to the Operations section of the User's Guide.

1. Put about 100 mL of water and 5 to 6 ice cubes into a 400 mL beaker.

2. Put 5 mL of water into a test tube and use a buret clamp to fasten the test tube to a support rod. The test tube should be situated above the water bath. Place a temperature sensor into the water inside the test tube

PART IIIA: Data Recording for Freezing

1. When everything is ready, click on the "REC" button to begin data recording. Then lower the test tube into the ice-water bath. The computer will collect data for a total of 15 minutes.

2. Soon after lowering the test tube, add about 40 mL of salt to the beaker while stirring with a stirring rod. Continue to stir the ice-water bath during Part III.

3. Gently but continuously move the sensor during the first 10 minutes of Part IIIA.

ï Be careful to keep the sensor in, and not above, the ice as it forms.

4. When 10 minutes have gone by, stop moving the sensor and allow it to freeze into the ice. Add more ice cubes to the beaker as the original ice cubes get smaller.

5. Continue collecting data until the data monitoring stops automatically at 15 minutes.

ï "Run #1" will appear in the list under Data in the Experiment Setup window.

6. Keep the test tube submerged in the ice-water bath until step 2 in Part IIIB below.

2. Click on the "REC" button to begin data recording. Then raise the test tube and fasten it into position above the ice-water bath.

3. Do not move the temperature sensor during Part IIIB.

4. Dispose of the ice water as directed by your teacher.

5. Put 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.

6. When 15 minutes have passed, the data recording will automatically stop.

2. Both columns of the Table will show Run #2. Click on the DATA menu button for the first column and select Run #1 from the data menu.

3. Both plots in the Graph will show Run #2. Click on the top DATA menu button and select Run #1 for the top plot.

If desired, adjust the size of the Graph with the Autoscale button. Optional: Select "Print Active Display" from the File menu to print the Graph.

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2. According to your data and graph, what is the freezing temperature of water? (Hint: Try using the Smart Cursor. Click on the "Smart Cursor" button . The cursor becomes a crosshair which you can drag over the graph in order to more easily determine the coordinates at any particular point.) What seems to be the melting temperature? Express your answers to the nearest 0.1 C.

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3. How does the freezing temperature of water compare to its melting temperature?

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4. Tell if the kinetic energy of the water in the test tube increases, decreases, or remains the same in each of these time segments during the experiment.

a. when the temperature is changing at the beginning and end of Part IIIA

b. when the temperature remains constant in Part IIIA

c. when the temperature is changing at the beginning and end of Part IIIB

d. when the temperature remains constant in Part IIIB