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Lab Partners:
Date:
Lab # 5: Which is Your Metal? Specific Heat Capacity and Calorimetry
Accelerated Chemistry 1
Problem
You are told that your “unknown” metal is a precious metal worth hundreds of dollars; you are not so
sure. Your goal is to use physical properties, such as heat capacity, to determine if your metal sample
is really precious.
Introduction
The specific heat capacity is the amount of energy required to change the temperature of one gram of a
substance by one degree Celsius. Each substance has a unique specific heat capacity due to the
arrangement of its atoms. In this lab, you will use a determination of the specific heat capacity to
identify an “unknown” metal.
Specific Heat Capacities (J/g°C)
Au: 0.130
Al: 0.8910
Zn: 0.3882
Ag: 0.230
Cu: 0.3844
Ni: 0.444
Pb: 0.128
Fe: 0.450
brass: 0.380
Prelab Assignment: Read the entire lab; then answer the following questions.
1. How do you know the final temperature of the metal?
2. Why do you use a boiling water bath to heat the metal?
Materials
calorimeter
ring stand
iron ring
wire gauze
graduated cylinder
Bunsen burner
thermometer
metal sample
Procedure
1. Set up the ring-stand, iron ring and wire gauze for heating as
demonstrated by your teacher. Adjust the height of the iron ring so the
tip of the inner blue flame from the Bunsen burner will just touch the
wire gauze.
2. Add about 100 mL of water to the beaker to a 250-mL beaker. Place the
250-mL beaker with water on the wire gauze. Light the Bunsen burner
as demonstrated by your teacher and bring the water to a rolling boil.
3. While the water bath is heating to a boil, record your sample letter.
Determine the sample’s mass by placing it in a tared weigh boat. Tie a
loop of strong thread to your sample as demonstrated by your teacher.
4. Measure 75.0 mL (~room temperature) water by pouring it into a tared
weigh boat on the electronic balance to determine its mass. Pour this water sample into your
calorimeter. Record the temperature of the water.
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5. GENTLY place the metal sample in the boiling water using crucible tongs. Do not allow the metal
to fall into the beaker and break the beaker.
6. Allow the metal to remain in the boiling water for at least two minutes. Record the temperature
of the boiling water.
7. Using the loop of thread, quickly transfer the metal from the boiling water to the calorimeter. Dab
some of the hot water off the metal before placing it into the calorimeter, but do this quickly and
deliberately. Cover the calorimeter.
8. Gently stir the water in the calorimeter for several seconds. DO NOT POKE A HOLE IN THE
CALORIMETER. STIR GENTLY!
9. Record the equilibrium temperature reached by the water/metal system in the calorimeter.
10. Repeat these steps at least once more. You do not have to refill the calorimeter. Simply measure
the initial temperature of the water before inserting the hot metal for another trial.
Clean Up
1. Turn off the Bunsen burner and put away.
2. Remove the metal sample from the calorimeter. Wipe it with a paper towel and place it in the
white bin on your desk.
3. Put one digital thermometer back in desk drawer. Leave the other in the white bin.
4. Pour the water out of the calorimeter. Take out the paper cup and set the calorimeter and cup to the
side along the back of the lab bench to dry.
5. Use beaker tongs to remove the 100-mL of water from the wire mesh. Pour down the drain.
When the apparatus is cool, take it apart and put the pieces back in the proper drawers. If it does
not cool in time simply pick up the apparatus from the top of the ring stand and move it to the back
of the lab bench.
6. Wash hands thoroughly before leaving the lab.
Data/Observations
Metal Code:
Trial 1
mass of metal
initial temp. of hot metal
(boiling temp of the water
bath)
mass of water
(calorimeter)
initial temp. of water
(calorimeter)
final temp. of water
(calorimeter)
AccelLab5-SpecificHeatCapacity
Trial 2
Trial 3
Same
Same
Same
Same
2
Analysis and Conclusions
1. Calculate the heat, q, absorbed by the water in the calorimeter in each trial. (q=m∆TCp)
Trial 1
Trial 2
Trial 3
2. How does the heat transferred to the water in the calorimeter compare to the heat transferred
from the metal in the calorimeter? Why?
3. Calculate the specific heat capacity of your metal in each trial.
Trial 1
Trial 2
Trial 3
4. Calculate the average specific heat capacity of your metal.
5. What is the identity of your metal?
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6. Assuming the identity of your metal is correct, what is your percent error in the specific heat
capacity?
7. Both of the following errors would cause a change in the calculated specific heat capacity for your
metal. Tell if the change would be to raise or lower your calculated value of the specific heat
capacity. Explain. Think about how you performed each calculation and how the following would change
your measurements and observations. Perform example calculations if necessary.
a. A significant amount of water is transferred with the hot metal.
b. The metal “cools off” as you transfer it from the hot water to the calorimeter because you
didn’t move quickly enough.
c. The calorimeter loses heat to the surroundings as you are stirring because you kept removing
the lid.
8. Supposed that instead of heating your metal in boiling water, you cooled it in ice water before
adding it to the calorimeter. Compared to the way you actually did the experiment, will the amount
of heat gained by the calorimeter water in the new procedure be greater or less? How will this
affect your percent error (higher, lower, or the same)? Explain.
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