Name______Date ______Period ______

Phase Change Lab

1. Problem/Purpose: What are the effects of the addition of thermal (heat) energy on a substance on the temperature of the substance while it is going through a change in state?

2. Research: Temperature is a measure of the average kinetic energy of the molecules in a substance. We will be using a thermometer to gather information about the energy transfer that occurs as ice melts and water heats up and comes to a boil. Remember that 0oC is the same as 32oF and 100oC is the same as 212oF.

3. Hypothesis: If thermal energy is added to ice (H2O), then the temperature will increase/decrease/stay the same (circle one) when the ice is changing state.

4. Experiment:

Materials- beaker, thermometer, ice, tap water, hot plate, and stop watch

Independent (Manipulated) Variable =______

Dependent (Responding) Variable = ______

1. Fill a beaker half-full with ice and then add tap water to cover the ice.

2. Use the stirring rod, not the thermometer, to gently stir the ice water.

3. Place the thermometer in the ice. It should not touch the bottom or the sides of the beaker.

4. Start the stopwatch.

5. After one minute has passed, record the temperature of the ice. Continue to read and record the temperature every minute. Do NOT stop the stop watch at any time during the experiment.

6. Once the first measurement has been taken, one person in the lab group should turn the hot plate on high. Continue taking temperature measurements each minute for 15 minutes.

7. After all of the water starts to boil, take three more temperature measurements (time for three additional minutes).

8. Turn off the hot plate. After the beaker cools, carefully dump the hot water in the sink and set the hot plate, beaker, thermometer, and stirring rod in the center of the lab table.

5. Data/Observations

Data Table

Time (minutes) / Temperature (◦C) / Observations
1
2
3
4
5
6
7
8
9
10
11
12
13
14
*15
16
17
18

Graph: Convert your data table into graphical form. Make sure you give your graph a title, choose the correct type of graph, label your axes appropriately, choose an appropriate scale for both axes, and plot your points correctly. I would also like for you to label which part of the graph shows the H2O in solid (ice) form, liquid form, and gas (vapor) form.


Title:

6. Conclusions

*Where did the energy that was added to the beaker of ice water come from?

The energy that was added to the beaker of ice water came from ______

______.

*Was this process an endothermic or exothermic process? (Look this up if you have never heard of it before.)

This process is an example of an ______process.

*What happened to the temperature while the ice was melting and the water was boiling?

The temperature ______while the ice melted and the water boiled.

*Where did the energy that was added to the system go while the ice was melting and the water was boiling?

The energy that was added to the system went ______while the ice was melting and the water was boiling.