Date __________
Lab Time ______
Name ___________________________
Specific Heat
Objective
Students learn the value of careful laboratory techniques while determining the specific heat,
C, of a solid such as copper, aluminum, or lead. The lab introduces the concept of specific
heat and uses conservation of energy for determination of C.
Background
Doesn’t it seem rather odd that on 90-degree days in June the local lake temperature is still
many degrees cooler? While a complete explanation of this phenomenon is rather
complicated, one important factor is the material (water) under consideration. Measurements
confirm that for a given amount of matter, water does not experience as large a temperature
increase for a given energy input, as other liquids (ethanol and acetone) and solids (copper,
silver, and glass). A measure of this property of the material is called its specific heat.
The lab experiment uses a concept (conservation of energy) that is discussed in a previous
exercise in order to determine C. As a review, conservation of energy means that the energy
content of a particular isolated system is fixed. In other words, the energy of the isolated
system cannot be gained or lost to the “outside” world. In the lab experiment the “system” is
the combination of cool water and a hot object immersed in it. From your experience, cool
water “warms up” and a hot object “cools down” when the two come into contact.
Eventually the two arrive at a common final temperature, and by conservation of energy, the
energy lost by the hot object is gained by the water.
Now how do we get specific heat from conservation of energy? The amount of energy that an
object absorbs (or releases) depends on the following factors: the mass of the material, the
temperature change of the material, and the composition of the material, characterized by its
specific heat. From these facts, a very simple equation follows:
Q = mC∆T
where Q is the energy (heat) absorbed or released, m is the mass of the material, C is the
specific heat, and ∆T is the temperature change. Equating Q lost by the hot object to Q
gained by the water and solving for C (solid) gives its specific heat, provided the other
factors are known.
Materials needed
Styrofoam cup, cardboard cover, electronic balance, 400 mL beaker, hot plate, specimen,
wire hook, and thermometer
___________
Specific Heat
1
Date __________
Lab Time ______
Name ___________________________
Procedure
Part I.
Derive the Equation for Csolid that will allow you to calculate the specific heat of a specimen
in Parts II and III. (NOTE: This can be done while you are heating your specimen)
Qlost (by specimen) = Qgained (by water )
Part II.
1. Weigh and record the mass of the specimen (solid).
2. Heat specimen in water bath for several at least 20 minutes. Assume temperature of
specimen after being heated to be that of boiling water (100 oC).
3. Record the Mass of the Styrofoam cup while empty.
4. Once the specimen’s have been heating long enough, add about 150 mL of cold water
from the tap into the empty Styrofoam cup. Determine the exact amount of water by
“weighing” (Measure the mass of the water and the Styrofoam together and then subtract
the mass of the Empty Styrofoam cup). Record the mass and temperature of the water.
5. With the wire hook place the specimen in the Styrofoam cup after shaking off any excess
hot water. Quickly place cardboard cover over the cup and insert the thermometer.
6. After the temperature stops increasing, record the final temperature of the water.
7. Calculate the specific heat of the specimen.
Part III.
Repeat the above procedure for a second specimen.
___________
Specific Heat
2
Date __________
Lab Time ______
Name ___________________________
Report Sheet – Data Analysis
Part II.
Type of Material of Specimen ___________________
Specific Heat (in cal/g oC)
Mass of specimen ____________ g
H2O (Water) - 1.0
Al (Aluminum) - .22
Cu (Copper) - .093
Pb (Lead) - .031
Zn (Zinc) - .094
Sn (Tin) - .055
Initial temperature of the Specimen __________oC
Mass of the Empty Styrofoam Cup ________________ g
Mass of Styrofoam Cup + Water ________________ g
Mass of water _______________ g
Initial temperature of water in Styrofoam cup __________oC
Final temperature of system __________oC
Specific heat of specimen ___________cal/goC
Calculations:
Part III.
Type of Material of Specimen ___________________
Mass of specimen ____________ g
Initial temperature of the Specimen __________oC
Mass of the Empty Styrofoam Cup ________________ g
Mass of Styrofoam Cup + Water ________________ g
Mass of water _______________ g
Initial temperature of water in Styrofoam cup __________oC
Final temperature of system __________oC
Specific heat of specimen ___________cal/goC
Calculations:
___________
Specific Heat
3
Date __________
Lab Time ______
Name ___________________________
Post lab questions:
1. How did your determined value of specific heat in Part I compare to the known value for
the specimen’s specific heat?
(Comment on your accuracy by calculating the Percent Error between your value and the actual
value of the specific heat.)
2. Where might the knowledge of the specific heat of materials be useful?
3. Where were the most probable sources for error in the experiment?
Summary/Conclusions:
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Specific Heat
4