Download Specific Heat of a Metal

Grade 12 Chemistry Lab
Specific Heat of a Metal
Chemists identify substances on the basis of their chemical and physical properties.
One physical property of a substance is the amount of energy it will absorb per unit of
mass. This property can be measures quite accurately and is called specific heat
capacity (c). Specific heat capacity is the amount of energy, measured in joules,
needed to raise the temperature of one gram of the substance one Celsius degree.
Often applied to metallic elements, specific heat can be used as a basis for comparing
energy absorption and transfer.
To measure specific heat in the laboratory, a calorimeter of some kind must be used. A
calorimeter is a well-insulated container used in measuring energy changes. The
calorimeter is insulated to educe the loss or gain of energy to or from the surroundings.
Energy always flows from an object at a higher temperature to an object at a lower
temperature. The heat gained by the cooler substance equals the heat lost by the
warmer substance, if we assume no loss of heat to the surrounding environment.
Heat lost = Heat gained
In this experiment, you will determine the specific heat constant of a metal. The metal
sample will be heated to a high temperature then placed into a calorimeter containing a
known quantity of water at a lower temperature. Having measured the mass of the
water in the calorimeter, the temperature change of the water (T), and knowing the
specific heat of water (4.18 J/(g C)), the heat gained by the water (lost by the metal)
can be calculated using
q = mcT. The equation can then be rearranged to calculate
the specific heat of the metal.
Materials
beaker (600 – 800 mL),
Styrofoam calorimeter,
tongs
two different metals
thermometer burner with ring, ring stand and wire gauze.
Objective
In this experiment you will:
 Measure the mass and temperature of water in a calorimeter
 Heat a sample of known mass to a specific temperature
 Calculate the change in heat for the water when the hot metal has been added
 Calculate the specific heat for the metal sample
Grade 12 Chemistry Lab
PROCEDURE
1. Setup the equipment to heat a beaker 1/3 full of water.
2. Measure a sufficient volume of water, enough to cover the metal sample, into
each calorimeter.
3. While the water is heating find the mass of the metal samples and record the
initial temperature of the water in the calorimeters.
4. Using the tongs, carefully place the metal samples into the heating water. Once
the water starts to boil measure the temperature of the water.
5. Using the forceps, carefully remove the metal sample from the boiling water and
immediately place it into a calorimeter.
6. Gently stir the calorimeter water once the metal has been added. Record the
highest temperature of the water in each calorimeter.
7. Repeat the procedure for a second trial with the same metal.
8. Complete steps 1-7 for a second metal.
ANALYSIS – Use an equation to show your work for calculations.
1. Prepare an organized data table that displays the data collected.
2. Calculate the specific heat for each of the metal samples showing all work.
3. Write an appropriate conclusion. In the conclusion be sure to state the average
specific heat capacity of the metals that were found and also determine the
identity of the metals (if possible). In this section state any sources of error and
make reasonable suggestions as to how to improve the lab.
Questions
1. What physical properties, other than specific heat, could your use to help you
identify the samples used in this experiment?
2. Why was water an excellent material to use in the calorimeters?
3. Propose a method for determining the specific heat for a metal like sodium that
reacts with water?
4. Calculate the specific heat of a metallic element, if 314 joules of energy are
needed to raise the temperature of 50.0 g sample from 25C to 50.0C.
Due by your class Thursday, February 11
You must include: data table, calculations, answers to questions #1-4 and a conclusion.
Be sure to ask any questions you may have before Thursday.