Name: ____________________________________ Partner: ___________________________________
Unit 4
Lab: Specific Heat Capacity
Introduction
As you have learned, each material has a characteristic specific heat capacity. In the Combustion Lab in Unit 3, you used
the specific heat capacity of water to determine the heat of combustion of candle wax. In this activity, you will use this same
property to identify an unknown metal sample. To accomplish this, you will investigate the transfer of thermal energy from
the hot metal sample to cool water. The quantity of thermal energy gained by the water is described by the following
formula:
Thermal energy gained by water (E) =
Mass of water (m) × Specific heat capacity of water (C) × Change in water temperature (∆T)
or
EH2O = qH2O = (m )(C )( ∆T )
H 2O
H 2O
H 2O
The thermal energy gained by the water is assumed to equal the thermal energy lost by the metal. To indicate the loss of
thermal energy, a negative sign is used:
Egained by water = − Elost by metal
or
(m )(C )( ∆T =(mmetal)(Cmetal)( ∆Tmetal)
H 2O
H 2O
H 2O
Remember that you are trying to find the specific heat capacity of the metal, Cmetal. All other values in the expression are
measured or are standard values that can be found in your textbook.
Before starting, read the procedure to learn what you will need to do, note safety precautions, and plan necessary data
collecting and observations.
Preliminary Work
Sketch to the right the calorimeter shown in Figure 4.42 (pg. 347 of your textbook):
You will use this sketch to assemble your calorimeter.
Procedure
1. Half-fill a 250- or 400-mL beaker with water. Place the beaker on a hot plate and start heating.
2. Obtain a metal sample and record a description of its appearance. Record in Data Table 1 on pg. 4 the number
written on the metal.
3. Determine and record the mass of the metal sample in the data table on pg. 4.
4. Carefully place the metal sample into the water that is heating in the beaker. (Caution: Do not drop the metal sample
into the beaker.) Allow the water to come to a boil, and keep boiling it for several minutes.
5. While the water is heating, obtain or assemble a calorimeter. Follow the sketch you made in the Preliminary
W ork section above.
6. Accurately measure a room-temperature water sample of about 160 mL. Record the exact volume(s) of water you
add to the calorimeter to the 0.1 mL place. Carefully pour the water into the calorimeter.
7. Measure and record the temperature of the water in the calorimeter.
8. Measure and record the temperature of the water boiling in the beaker on the hot plate.
9. After the water has boiled for 2 to 3 min, use tongs to remove the metal sample from the water, gently shake the
excess water from the metal, and quickly lower the sample into the calorimeter. (Caution: Do not drop the metal
sample into the calorimeter.)
10. Gently stir the water in the calorimeter, and record its temperature in Data Table 2 every 30 sec until it reaches a
maximum value and starts to drop. Record the maximum temperature in Data Table 1.
11. Repeat Steps 3 through 10 using the same metal sample and fresh water in the calorimeter.
12. Wash your hands thoroughly before leaving the laboratory.
Name: ____________________________________ Partner: ___________________________________
Data Analysis
1. Find the quantity of thermal energy absorbed by the water in the calorimeter. Calculate the energy absorbed for both
trials separately:
2. Assume that the thermal energy absorbed by the water equals the thermal energy released by the metal sample. In
addition, assume that the metal sample was initially at the temperature of the boiling water. Calculate the specific heat
capacity of the metal for both trials. Record each value to 3 places after the decimal point.
3. Average the calculated specific heat capacities for both trials. Record each answer to 3 places after the decimal point.
Show your work:
Questions
1. Using your calculated specific heat capacity value, as well as the data provided in Table 4.4 (page 345 of your
textbook), identify your metal sample [add tin (0.21 J/g • oC ) and magnesium (1.02 J/g • oC ) to the data
in the table]
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2. The extent of certainty you have about the actual identity of your metal sample depends in part on sources of error in
the laboratory procedure. List and explain several potential sources of error in the procedure that you followed. For
each, include whether the source of error is human or experimental.
a. ___________________________________________________________________________
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b. ___________________________________________________________________________
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c.
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d. ___________________________________________________________________________
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Name: ____________________________________ Partner: ___________________________________
3. Closely related to sources of error are any simplifying assumptions you made to complete your laboratory task and
calculations.
a. List some assumptions that you made in completing this investigation and its calculations.
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b. Evaluate at least one assumption in terms of how it could adversely affect your calculated result.
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4. A recycling company decides to separate the various metals it receives by using the different specific heat capacities of
the metals.
a. Do you think that this is a reasonable plan? Explain.
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b. Propose an alternative method for separating the metals.
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Name: ____________________________________ Partner: ___________________________________
Data
Description of metal sample:
Data T able 1
Trial One
Trial Two
Metal #:
Mass of the metal sample
Volume of water in the calorimeter
(to the 0.1 place)
Beginning temperature of water in
the calorimeter (to the 0.1 place)
Temperature of water on the hot
plate (Initial temperature of metal)
(to the 0.1 place)
Final temperature of the water in
the calorimeter (to the 0.1 place)
Temperature change of water in
calorimeter (to the 0.1 place)
Temperature change of metal (to
the 0.1 place)
Data T able 2
Time after emersion of metal in water
Water temperature (°C)
Trial One
Water temperature (°C)
Trial Two