LAB ACT 7 Calorimetry

Name: ___________________________
Calorimetry: Determination of the

Specific Heat of a Metal
LABORATORY ACTIVITY NO. 7
Introduction
Any chemical or physical change involves a change in energy. Heat is a form of

energy that can be observed as a flow of energy. Heat can pass spontaneously from an
object at a high temperature to an object at a lower temperature. Two objects in contact at
different temperatures, given enough time, will eventually reach the same temperature.
The flow of heat energy can also be either into or out of a system under study.
The amount of heat can be measured in a device called a calorimeter. A

calorimeter is a container with insulated walls. The insulation prevents a rapid heat
exchange between the contents of the calorimeter and the surroundings. In the closed
environment of the system, there is no loss or gain of heat. Since the change in
temperature of the contents of the calorimeter is used to measure the magnitude of the
heat flow, a thermometer is included with the calorimeter. The specific heat of any
substance can be determined in a calorimeter.
The specific heat is an intensive physical property of a substance and is the

quantity of heat (in calories) necessary to raise the temperature of one gram of substance
by one degree Celsius.
Objectives:
1. To construct a simple calorimeter.

2. To measure the heat capacity of the calorimeter.
3. To measure the specific heat of a metal.
Materials:
1. Metal pellets 2. Styrofoam cups (2) 3. Lid for Styrofoam cups 4. Metal
stirring loop 5. Thermometers, 110C (2) 6. Latex rubber ring 7. Volumetric
pipet, 50-mL 8. Thermometer clamp
Procedure:
Determination of the Heat Capacity of the Calorimeter
1. Construct a calorimeter. The two dry 8-oz. Styrofoam cups are inserted one into the
other, supported in a 250-mL beaker. The plastic lid should fit tightly on the cup. With a
suitable-sized cork borer, make two holes in the lid; one hole should be near the center
for the thermometer and one hole to the side for the stirring wire. In order to keep the
thermometer bulb 2 cm above the bottom of the inner cup, fit rubber ring (cut from latex
rubber tubing) around the thermometer and adjust the ring by moving it up or down the
thermometer.
Figure 7.1 The Styrofoam calorimeter.
2. Since the density of water is nearly 1.00 g/mL over the temperature range for this
experiment, the amount of water used in the calorimeter will be measured by volume.
With a volumetric pipet, place 50.0 mL of cold water in the calorimeter cup; determine
and record the mass (1). Cover the cup with the lid-thermometer-stirrer assembly. Stir the
water for 5 min., observing the temperature during the time; record the temperature at 1-
min. intervals on the Data Sheet. When the system is at equilibrium, record the
temperature to the nearest 0.20C.
3. With a volumetric pipet, place 50.0 mL of water in a clean, dry 150-mL beaker;
determine and record the mass (2). Heat the water with a low flame until the temperature
of the water is about 700C. Allow the hot water to stand for a few minutes, stirring
occasionally during this time period. Quickly record the temperature to the nearest 0.20C
(4) and pour the water completely into the calorimeter that has been assembled and has
reached equilibrium (Fig. 7.1).
4. Replace the cover assembly and stir the contents gently. O ,kjbserve the temperature
for 5 min. and record the temperature on the Data Sheetevery 30 sec. during that 5-min.
period. Plot the temperature as a function of time, as shown in Figure 7.2. (Use the graph
paper). Determine from your curve the maximum temperature by extrapolation and
record it.j
Figure 7.2. Plot of temperature (Y) vs. time (x).
(5). Determine the T (change in temperature). From the data, calculate the heat capacity
of the calorimeter according to the calculations on the Report Sheet.
Determination of the Specific Heat of a Metal
1. Dry thme Styrofoam cups used for the calorimeter calibration. Reassemble the
apparatus as in Fig. 7.1.
2. With a volumetric pipet, place 50.0 mL of cold water in the calorimeter cup; record the
mass (1).
3. Obtain an unknown metal sample from your instructor. Record the number of the
unknown on the Report Sheet.
4. Weigh a clean, dry 50-mL beaker to the nearest 0.01 g (2). Place about 40 g of your
unknown sample in the beaker and reweigh to the nearest 0.01 g (3). Determine the mass
of the metal by subtraction (4). Pour the sample into a 16 150 mm clean, dry test tube.
5. Place the test tube in the water bath as shown in Fig. 7.3. Be sure that all of the metal
in the test tube is below the surface of the water. Heat the water to a gentle boil and keep
the test tube in the bath for 10 min. Make certain that water does not splash into the test
tube.
Figure 7.3 Assembly for heating the metal.

6. While the metal is heating, follow the temperature of the cold water in the calorimeter
for 5 min.; record the temperature on the Data Sheet at 1-min. intervals. After 5 min.,
record the temperature on the Report Sheet of the cold water to the nearest 0.20C (5).
7. After 10 min. of heating the metal, observe and record the temperature on the Report
Sheet of the boiling water in the beaker to the nearest 0.2 0C (6). Obtain and use another
thermometer for the calorimeter.
8. All steps must be done quickly and carefully at this point. Remove the test tube from
the boiling water; dry the outside glass with a paper towel; remove the lid on the
calorimeter; add the hot metal to the calorimeter. Be careful no water is added to or lost
from the calorimeter on the transfer.
9. Record the calorimeter temperature on the Data Sheet as soon as the apparatus has
been reassembled. Note the time when the temperature is determined. Stir the water.
Continue to follow the temperature, recording the temperature on the Data Sheet every 30
sec. for the next 4 min. 10. Plot the temperature as a function of time, as shown in Fig.
7.2. (Use the graph paper). Determine from your curve the maximum temperature; record
the
temperature on the Report Sheet (7). Determine the T. From the data, determine the
specific heat and the atomic mass of the metal.
Conclusions:
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Applications:
1. What is a calorimeter?
,
2. A student has a hot iron rod and thrusts it into a container of cold water. Explain what
will happen in terms of heat flow.
3. Why is water a better coolant than ethyl alcohol?
4. Would a tin cup be a good container for a calorimetry experiment (versus a Styrofoam
cup)? Explain. (Think about hot coffee in a tin cup vs. a Styrofoam cup.)
5. Does this experiment violate the Principle of Conservation of Energy? Explain.
Specific Heat Values for Some Common Substance
Specific Heat (cal/g 0C)

Lead (Pb) 0.038 Glass 0.12 Tin (Sn) 0.052 Table salt (NaCl) 0.21 Silver (Ag) 0.056
Aluminum (Al) 0.22 Copper (Cu) 0.092 Wood 0.42 Zinc (Zn) 0.093 Ethyl alcohol
(C2H6O) 0.59 Iron (Fe) 0.11 Water (H2O) 1.00
6. If 20 g of water is heated, and its temperature rises from 200 to 250C, then how much cal
have been absorbed.
7. An unknown hot metal at 100.00C with a mass of 50.03 g was mixed with 40.11 g of
water at a temperature of 21.50C. A final temperature of 30.60C was reached. The heat
gained by the water is …….
8. The specific heat from Problem 7 is 0.11 cal/g 0C (to two significant figures). The
approximate atomic weight is calculated to be…..
9. The temperature of 50.0 mL of warm water is 36.9 0C. The temperature of 50.0 mL of
cold water in a calorimeter is 19.90C. When the two were mixed together in the
calorimeter, the temperature after mixing was 28.10C. What is the heat capacity of the
calorimeter? (assume the density of water is 1.00 g/mL).
Enrichment:
https://www.youtube.com/watch?v=XfyTBxrq1ic
https://www.youtube.com/watch?v=wZZ9UTlgMZQ
https://www.youtube.com/watch?v=28dNPDqk0L4
https://www.youtube.com/watch?v=28dNPDqk0L4
https://www.coursera.org/lecture/physical-chemistry/introduction-to-experiment-D0c8q

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Name: ___________________________

Calorimetry: Determination of the

Any chemical or physical change involves a change in energy. Heat is a form of

The amount of heat can be measured in a device called a calorimeter. A

The speciﬁc heat is an intensive physical property of a substance and is the

1. To construct a simple calorimeter.

Determination of the Heat Capacity of the Calorimeter

Figure 7.1 The Styrofoam calorimeter.

Determination of the Speciﬁc Heat of a Metal

Figure 7.3 Assembly for heating the metal.

3. Why is water a better coolant than ethyl alcohol?

5. Does this experiment violate the Principle of Conservation of Energy? Explain.

Speciﬁc Heat Values for Some Common Substance

Speciﬁc Heat (cal/g 0C)

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