EXPERIMENT 12 – SPECIFIC HEAT OF A METAL
Name__________________Per _____
OBJECTIVE:
To determine the specific heat of lead.
MATERIALS:
safety goggles
1 250 mL beaker
balance
1 glass stir rod
Watch glass
1 foam cup
1 large test tube
lead shot, Pb
PROCEDURE:
As you perform the experiment, record your data in Table 1.
Glove
Hot water bath
1 small plastic cup
1 100 mL graduated cylinder
Windows PC
Temperature probe
LabQuest Interface
1. Turn on the computer and Lab Quest. Open Logger Pro 3.8.4. Click on file, open, Chemistry with Vernier,
01 Endo-Exothermic. Change sensor to direct-connect temp, click Connect.
2. Tare out the mass of a small plastic cup. Add between 80 and 120 grams of lead shot, Pb, to the cup.
Record the mass of the lead to the nearest 0.01 g in Table 1.
3. Construct a paper funnel from your lab sheet. Use the funnel to carefully transfer the lead
shot to a large, dry test tube. Be careful to pour the lead shot into the tube slowly so that the bottom
of the test tube is not broken in this process. Place the test tube in the water bath, making sure that
the lead shot is below the level of boiling water in the beaker (See Figure 1). Allow the test tube to
remain in the boiling water bath for at least 10 minutes. Proceed to Step 4 while the lead shot is
heating.
4. Carefully measure out 100 mL of tap water in a graduated cylinder, and pour out the water into the foam
cup. Place the cup in a 250 mL beaker for support (See Figure 2). Insert the temperature probe.
About one minute before the time has elapsed for heating the lead shot, hit the COLLECT button.
5. Assume the lead is the same temperature as that of the boiling water and that the water is boiling at
100°C. Record this temperature in the data table.
6. When time has elapsed, remove the probe from the foam cup and carry the beaker and cup over to the
hot plate. Remove the test tube from the bath, using the orange glove(s). Carefully, but quickly,
pour the lead shot into the water in the foam cup. At the lab station, replace the probe and hold the
probe so that the probe DOES NOT TOUCH THE LEAD SHOT. Use a stirring rod to
continuously and gently stir the lead shot.
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EXPERIMENT 12 – SPECIFIC HEAT OF A METAL
7. Observe as the temperature is being recorded. Once the temperature has reached a maximum, hit the STOP
button. Using the STAT button, determine the minimum temperature (the initial temperature of water in the
foam cup) and the maximum temperature (the temperature of the water and the lead). After recording these
two temperatures, select Data on the toolbar and choose Clear all Data.
8. Using the watch glass, pour the water off the lead shot into a basin provided by your teacher. Return the
metal to be dried.
9. Repeat steps 2-8 for the second trial. Remember to clear all data. Do not save changes. Exit Logger Pro.
DATA TABLE 1
TRIAL 1
TRIAL 2
MASS OF LEAD SHOT, g
VOLUME OF WATER IN FOAM CUP, mL
INITIAL TEMPERATURE OF WATER IN CUP, °C (STEP 7)
INITIAL TEMPERATURE OF LEAD, °C (TEMPERATURE OF BOILING
WATER FROM STEP 5)
MAXIMUM TEMPERATURE OF LEAD AND WATER, °C (END OF STEP 7)
ANALYSIS:
1.
Show all work, including units for each trial.
Calculate the mass of water in the foam cup. The density of water is 1.0 g/mL.
mass = density x volume
TRIAL 1
2.
Calculate the change in temperature of the water in the foam cup. (ΔTwater) for each trial.
TRIAL 1
3.
TRIAL 2
TRIAL 2
Calculate the change in temperature of the lead shot when placed on the foam cup (ΔTlead).
TRIAL 1
TRIAL 2
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EXPERIMENT 12 – SPECIFIC HEAT OF A METAL
4.
Calculate the heat gained by the water in the cup. The amount of heat energy gained by the water in the
cup will be calculated by the following equation.
(Cwater= 1cal/g x oC)
heat gained water= specific heatwaterx masswaterx ΔTwater
TRIAL 1
5.
TRIAL 2
Remembering that heat gainedwater= heat lostlead, calculate the specific heat of lead. The specific heat of
lead can be calculated by rearranging the following equation.
heat gainedwater= specific heatlead x masslead x ΔTlead
TRIAL 1
6.
TRIAL 2
Calculate the average specific heat of lead for the two trials.
AVERAGE SPECIFIC HEAT _____________
CONCLUSIONS: Show all work or answer in complete sentences.
1.
The accepted value for the specific heat of lead is 0.038 cal/g•°C. Calculate the percent error in the
specific heat value that you determined experimentally.
percent error = [accepted value — experimental value] X 100%
accepted value
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EXPERIMENT 12 – SPECIFIC HEAT OF A METAL
2. Compare your value for the specific heat of lead to the values obtained by your classmates. Obviously, this
procedure allows for many assumptions that lead to sources of error. List two assumptions made (not
measurement error) that may account for the relatively large sources of error obtained by you or your classmates.
a._______________________________________________________________________
________________________________________________________________________
b.__________________________________________________________________________
____________________________________________________________________________
3. Specific Heat is a physical property. Explain what this means.
_____________________________________________________________________________
______________________________________________________________________________
_____________________________________________________________________________
4. Two 40 gram samples of metals are heated. Sample A has a specific heat equal to
0.049 cal/g x oC and Sample B is lead. Both samples are initially at 25oC. After each sample has absorbed
100 kilojoules of energy, will the final temperatures of the samples be the same?
Explain.__________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
*5. Energy is conserved. Therefore,
heat lostPb = - heat gainedwater
qPb = - qwater
CPb x mPb x (tf -ti)Pb = - Cwater x mwater x (tf - ti)water
In the space below, SOLVE directly for CPb from Trial 1 using this equation. Your answer should be
equal to solution #5 in the Analysis section on the previous page. How do they compare?___________
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