Purpose:
The purpose of this lab is to calculate the specific heat of
aluminum using calorimetry.
Background:
The specific heat capacity of a substance is the amount of energy
required to raise the temperature of one gram of that substance 1˚C. The
specific heat capacity of liquid water is 4.184J/g˚C. Mathematically, for
systems at constant pressure, with no volume changes, q = mC∆T, where
q=change in heat content
C=specific heat constant
M=mass of the substance
∆T=change in temperature
In this experiment, a known mass of a metal is mixed at a high
temperature with a known mass of water at room temperature in a
coffee-cup calorimeter. By measuring the initial temperature of each
substance and the final temperature of the system, the specific heat of the
metal can be determined. The formula used is:
qwater = -qmetal
mwaterCwater∆Twater = -mmetalCmetal∆Tmetal
Materials:
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500mL beaker
Hot plate
Celsius thermometer
Test tube, stopper, and
clamp
Analytical balance
Aluminum sample
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3 Styrofoam cups
Graduated cylinder
Distilled water
Calculator
Blow dryer
Procedure:
1) Fill a 500mL beaker about ¾ full of tap water, and heat the beaker on the
hot plate until the water is boiling.
2) Obtain a metal sample of aluminum, mass the sample using the analytical
balance, and record the measurement.
3) Put the massed metal sample into a dry test tube. Clamp the test tube in
the beaker of boiling water, making sure that the test tube does not
touch the bottom of the beaker. The water level in the beaker should be
above the level of the metal in the test tube. Put the thermometer in the
test tube through the stopper so that it makes maximum contact with the
aluminum pieces.
4) Take a dry Styrofoam cup and place it in another. Cut the top of a 3 rd one
to form the lid of the calorimeter. Insert the thermometer through the top
of the “coffee-cup” calorimeter.
5) Mass 60.0g of water into the calorimeter, and record the temperature.
This is the initial temperature of the water.
6) When the temperature of the aluminum pieces reaches above 90 degrees
Celsius, carry out the following operation as quickly as possible:
a. Record the temperature of the aluminum. This is the T initial of the
aluminum.
b. Dump the hot metal into the calorimeter.
c. Record the maximum temperature reached. This is T final for both
the water and the aluminum.
7) Repeat steps 5-10 at least twice. The metal need not be reweighed, but it
must be thoroughly dried before reheating. Use the blow dryer. The
calorimeter must be dried and a fresh 60.0mL of distilled water should be
used each time. If the tap water level in the heating beaker drops below
the level of the metal, add more tap water as required and continue to
heat.
8) Dry the metal sample thoroughly and return it to its original location.
9) Calculate the specific heat of the metal from each trial, and subsequently
the average specific heat of the metal.
Conclusion:
The specific heat content of aluminum is 0.08J/g°