Page 1 – Separation of a Mixture
Heat Capacity of Various Metals
Background
Matter is all around us. Sometimes in things that we can see, and sometimes in things that we
cannot see but nevertheless know that they are there. Take air for instance. Even though you
cannot see it, you know that it is there, especially on a windy day. When the air is moving it is
also displaying another fundamental fact about the universe. Matter contains energy. It comes
in many forms. It can be energy of motion like the kinetic wind energy we just mentioned or
some other form like heat, light, electrical, or chemical energy.
The first law of thermodynamics states that energy can neither be created nor destroyed
although it can be changed from one form of energy into another. This law is often called the
law of conservation of energy for this reason. We say that energy flows through the universe
from place to place. On earth, this energy flow is often in the form of heat.
Heat energy can flow in one of two ways. First, heat energy can be transferred through the
motion of a fluid, such as air or water, in a process called convection. Hotter fluid particles
become less dense while colder fluid particles become denser. These density differences cause
hotter particles to rise in the fluid, while colder particles sink in the fluid. This has the effect of
transporting heat from one place to another within the fluid.
In solids, heat is transferred by the direct contact of two substances in a process called
conduction. You have experienced this if you have every accidentally touched a very hot object.
Temperature is a measure of energy in a substance. For instance, when the temperature of an
object gets hotter, we know that it has absorbed energy from its surroundings.
In this laboratory, you will investigate how heat can be transferred from metal objects (solids)
to water (a fluid). Just how much energy can be absorbed or released by these substances? Well
each substance is different depending on its chemical makeup. Some substances have a high
heat capacity, like water, and can absorb a large amount of heat energy without changing their
temperature. Other substances like some metals have low heat capacities and will get hot very
quickly when heat energy is applied to them.
It is important to keep in mind that this heat
capacity is a measure of energy that can be
absorbed or released by a certain amount of a
substance to change its temperature. Therefore,
each substance has a specific heat that it can
absorb. This specific heat is constant for all
matter of the same type. It is measured in
calories per gram degree Celsius (cal/g•°C) or
joules per gram degree Celsius (J/g•°C). The
specific heats of some common substances are
listed in Table 1.
Specific heat capacities of common
substances
Specific heat Specific heat
Substance
(cal/g•°C)
(J/g•°C)
Water
1.000
4.184
Aluminum
0.220
0.910
Copper
0.092
0.390
Carbon Steel
0.120
0.490
Page 2 – Separation of a Mixture
Objectives
In this experiment, you will
 Determine the specific heat capacities of various metal samples.
Pre-Lab Questions
1. Explain how heat energy flows between substances?
2. Describe the relationship between an object’s specific heat and its ability to resist
changes to its temperature?
3. How will you determine the specific heat of an unknown metal in this laboratory?
4. A substance’s specific heat is a physical property of the substance. What does this mean?
Materials
Computer with Vernier LoggerPro
LabPro interface
Temperature sensor
Electronic balance
Hot plate
Boiling stones
400 mL beaker
Graduated cylinder
Polystyrene foam cup(s)
Metal objects of various types
Beaker tongs
Safety Precautions
The materials in this lab activity are considered relatively nonhazardous. Observe all normal laboratory
safety procedures. Wear chemical splash goggles whenever working with chemicals, glassware, or heat in
the laboratory.
Procedure
1. Set up a boiling water bath for use in step 7. Half-fill a 250-mL beaker with water. Place the
beaker on a hot plate and add a few boiling stones. Set the hot plate on a high setting to heat
the water to boiling.
2. Connect the LabPro to the computer if it is not already done for you. Plug the temperature
sensor into the LabPro device. Ensure that the LabPro device is plugged in.
3.
Login to the computer. Open the LoggerPro 3.8.6.1 program from the Vernier software
folder under the Start menu. You should see a data recording box in the lower left portion of
the screen which displays the current temperature. If this does not occur, check the
connections of the LabPro to the computer to ensure that they are secure and that the
LabPro has power and is working.
4. Using the electronic balance find the weight (mass) of each metal sample. Record this
information in Data Table 1.
Page 3 – Separation of a Mixture
5. Place your metal samples in the boiling water bath for 5 minutes. While they are boiling,
complete steps 6-7.
6. Measure 100 mL of water using the graduated cylinder. Carefully pour this water into the
foam cup.
7. Place the end of the temperature sensor into the water in the foam cup and allow the
temperature reading to stabilize. Record the initial temperature in Data Table 1.
8. Using the tongs, remove one of the metal samples from the boiling water bath, quickly
shake off excess water, and place the metal into the foam cup of water. Ensure that the metal
sample is completely submerged and that it is not directly touching the temperature sensor.
9. Press the Collect button on the LoggerPro program. Wait until the temperature stabilizes
and record this value as your final temperature in Data Table 1.
10. Carefully remove the metal sample from the water and allow it to cool completely on your
benchtop. Be careful, it may still be warm to the touch. Pour out the water in the foam cup.
11. Repeat steps 6 through 10 for all metal samples to be tested.
12. When you have finished, save your temperature data as a file in your H:\drive. Log out of
the computer and clean any spills or mess from your lab station. Leave the equipment neat
and orderly as you found it.
Results
Data Table 1
Quantity
Unknown #1
Water
Metal #1
Unknown #2
Water
Metal #2
1.000
1.000
Mass (g)
Specific Heat
(cal/g•°C)
Initial temperature
(°C)
Final
temperature (°C)
Calculations:
Calculate the specific heat for each unknown metal sample. Use the equation Q = m • c • ΔT
where Q = heat energy, m = the mass of the substance, c = the specific heat of the substance, and
ΔT = the change in temperature of the substance.
Page 4 – Separation of a Mixture
Conclusion/Discussion Questions:
In your Discussion, you should address the following questions or topics:
1. Using your calculations of the specific heat of the metal samples, predict the metal used in
each sample. Use a chart of the known specific heats of metal samples like the one on the
front of this lab to assist you.
2. Discuss how you were able to use the law of conservation of energy to complete the
objective of this laboratory, namely to figure out the specific heat of unknown metals.
3. What might have been some sources of experimental error in your laboratory? Namely, how
might the design of the experiment prevented you from getting the correct answer.
4. What might have been some sources of personal error in your laboratory? Namely, were
you careless in any way that you conducted the experiment such that your answer may be
inaccurate. If so, how?
5. Where might the principles or techniques of this laboratory be used in everyday life? In
industry and manufacturing? In generating energy? In your home?
References:
McGuire, Saundra Y. Instructor Teaching Guide and Complete Solutions for Introductory
Chemistry, 3rd ed. Pearson Benjamin Cummings, 2007.