University of Virginia
Physics Department

## Change of State

A Physical Science Activity

### Student Activity

Materials

• Glass beaker, 600 mL
• 5-10 ice cubes
• 200 mL water
• Thermometer
• Hot plate
• Clock or wristwatch timer
• Graph paper
• Small clamp

Procedure

1. Fill a 600 mL beaker about half full with ice.
2. Pour 200 mL water in the beaker along with 5-8 ice cubes. Wait several minutes, and measure the temperature of the mixture.
3. Turn on the hot plate to medium. Place the beaker with the ice and water on the hot plate and warm it slowly.
4. Every minute read the temperature of the mixture and record it. Use the small clamp to hold the thermometer off the bottm of the beaker.
5. Watch the mixture and record the time and temperature. Describe the mixture and note when all the ice has melted.
6. Continue to heat the water and record its temperature.
7. Note the time and temperature at which the water boils. Continue to record the temperature each minute for five minutes after it begins boiling. Stop before all of the water has boiled. Do not let the thermometer rest on the bottom of the beaker.
8. Plot your results on a sheet of graph paper. Label the x-axis "Time" and the y-axis "Temperature". Label what happened at various points on the graph.

Data Sheet

 Temperature of Water Description of Mixture Time (minutes) Temperature of Water Description of Mixture Time (minutes)

1. Using your graph, describe how the temperature of the water changed over time.

2. Explain any horizontal portions of your plot. At what temperature did they occur?

3. At what temperature did the ice completely melt? At what temperature did the water begin to boil?

4. What was the maximum temperature reached by the water? Explain this limit.

5. At what temperature did the added energy contribute to the heat of fusion? The heat of vaporization?