Lab Activity
Heating and Cooling Curves
Total Energy
Name:__________________
Date:______________
Purpose: To observe the temperature of water over a period of time. To determine the shape
of a heating/cooling curve. To learn more about heat transfer during changes of state.
Materials: Ice, water, stirring rod, thermometer, beaker, hot plate, scale
Method:
1. Collect the necessary materials. Find the mass of the beaker. Fill the beaker with an icewater mixture (about half of the mixture should be ice and half water). The beaker
should be about 2/3 of the way full. Mass the beaker again and determine the mass of
the water.
2. Place the beaker on the hot plate. Before turning on the hot plate, determine the initial
temperature of the mixture and record it in the table at time zero.
3. Begin stirring the mixture and turn on the hot plate. Do not stop stirring until the
experiment is finished.
4. Take the temperature every 30 seconds and record it in the table. Also record any
observations you may have, for example the state of the mixture, solid, liquid or gas or a
mixture of these.
5. When the water boils continue to take measurements for another five minutes. Then
turn off the hot plate and clean your station. Rinse, dry and return the beaker and
thermometer. Ensure the hot plate is unplugged and wipe off your bench with a damp
cloth.
Observations:
Record your observations on the table attached.
Analysis:
1. Plot a temperature (y axis) versus time (x axis) graph. Use best fit line segments for each
part of the graph where the dots are in a line. Do not connect the dots, and do not do
one best fit line for the entire graph.
2. Why is this graph called both a HEATING and a COOLING curve? How would you draw a
cooling curve?
3.
What happened to the temperature when the ice was melting? How would you
calculate the change in energy at this stage of the experiment? What happened to the
temperature after all the ice had melted? How would you calculate the change in energy
at this stage of the experiment? What happened to the temperature when the water
was boiling? How would you calculate the change in energy at the stage?
4. Give an explanation for what happened to the temperature as you described it in
question 3.
5. Calculate the amount of energy during each step of the curve.
6. Find the total amount of energy changed during your experiment.
7. The melting point of ethanol is -115oC and the boiling point is 78oC. Sketch a heating
curve and calculate the total energy required for 3.5 g of ethanol being heated from 125oC to 95oC.
Table 1.0
Time (min)
0
0:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
5:30
6:00
6:30
7:00
7:30
8:00
8:30
9:00
9:30
10:00
10:30
11:00
11:30
12:00
12:30
13:00
13:30
14:00
14:30
15:00
15:30
16:00
16:30
17:00
17:30
18:00
18:30
19:00
19:30
20:00
20:30
21:00
21:30
22:00
22:30
23:00
23:30
Temperature (oC)
Comments
Time (min)
24:00
24:30
25:00
25:30
26:00
26:30
27:00
27:30
28:00
28:30
29:00
29:30
30:00
30:30
31:00
31:30
32:00
32:30
33:00
33:30
34:00
34:30
35:00
35:30
36:00
36:30
37:00
37:30
38:00
38:30
39:00
39:30
40:00
40:30
41:00
41:30
42:00
42:30
43:00
43:30
44:00
44:30
45:00
45:30
46:00
46:30
47:00
47:30
Temperature (oC)
Comments