Name: _______________________________
Identification of an Unknown Metal
Purpose: In this lab you will use two physical properties, specific heat capacity, to try to identify an unknown
metal.
Introduction (Background Information): Like density, specific heat capacity is an intrinsic or intensive
property that can be used to characterize or even identify a substance. Specific heat capacity, often simply
called specific heat, is the amount of heat energy needed to raise the temperature of one gram of a substance by
1 C. In the metric system, its units are J/gC and is calculated according to the formula, q = mcT, where q is
the heat in Joules, m is the mass of the sample being heated in grams, and T represents the temperature change
in degrees Celsius. The specific heat capacity of water is 4.184 J/gC. In this lab you will be measuring the
specific heat of an unknown metal by measuring the amount of heat it transfers to a known amount of water. To
do this you will use a calorimeter.
Safety Precautions:
Goggles must be worn. Please do not stir things with the thermometers. Use a stirring rod.
Known values for reference
Metal
Specific Heat Capacity
(J/g·ºC)
Lead
0.1276
Tin
0.2274
Silver
0.23502
Copper
0.38452
Nickel
0.4442
Zinc
0.39
Aluminum
0.9025
Magnesium
1.024
Part I: Specific Heat
Materials
3-5 pieces of unknown metal (be sure to dry it off if it is wet)
Balance
Hot Plate
Beaker (250 mL or larger)
Calorimeter
Thermometer
Tongs
Tap water
Procedure:
Heating the metal:
Find and record the mass of the metal pieces.
Place the metal pieces in a beaker and add approximately 100 mL of tap water. Heat on a hot plate (set the
hot plate to about 5). When the water is boiling, measure and record the temperature of the water. Do not let
the thermometer rest on the bottom of the beaker, and don’t assume that the boiling temperature is exactly
100.0C! Remove the thermometer and let it cool.
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Keep the metal in the boiling water for at least 3 more minutes.
Preparing the calorimeter:
While the water is heating, zero the balance with the empty Styrofoam cup. Then add tap water to the
Styrofoam cup so that the water level looks about 1 inch deep. Record the mass of the water.
Measure and record the temperature of the tap water.
Using the calorimeter – measuring specific heat:
After the metal piece has been in the boiling water for at least 3 minutes, remove the hot metal using tongs and
quickly drop the metal into the Styrofoam cup. Immediately put the thermometer back in to the cup to monitor
the water temperature. The temperature will rise quickly and then level off. Record the water’s highest
temperature.
Table I. Specific heat data
Mass of metal
Temperature of boiling water
Initial temperature of hot metal
Initial temperature of water in cup
Final temperature of water + metal
Mass of tap water in cup
Specific Heat Capacity of water
4.18 J/g·ºC
Change in tap water temperature
(use the absolute value of the difference)
Change in metal temperature
(use the absolute value of the difference)
1. Using the formula q=mc∆T, calculate the heat (q) absorbed by the water. Show your work!
(Think….should you use the mass of the water here or the mass of the metal? Which change in temperature
should you use? The specific heat of water is given above.)
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2. How much heat was lost by the metal? Explain how you know.
3. Using your rearranged formula, calculate the specific heat of your unknown metal. Show your work!
(Think….. should you use the mass of the water here or the mass of the metal? Which change in temperature
should you use?)
Analysis Questions
4. What do you believe is the identity of your unknown metal? Discuss your conclusion and how certain you
feel. Use full sentences and compare your experimental values with the theoretical, “accepted values” listed
on the first page.
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5. Which metal would cause the greatest increase in the temperature of the water in the calorimeter: the one
with the higher specific heat, or the one with the lower specific heat? Explain.
6. If equal masses of two metals are heated to a temperature of 100 °C, which would cause a more severe burn
– the one with the higher specific heat or the one with the lower specific heat? Explain.
7. Calculate the percent error for your specific heat measurement based on what metal you think you have.
Please show your work!
 "true" value - average experimental value 
% Error=
×100%
"true" value


8. No experiment is perfect. What might be a source of error in this experiment and how would it have affected
your results? (In others word explain why the source of error would make your experimental results larger
or smaller in magnitude than the theoretical answer.)
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