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IB Physics Practical 6:
Topic 3
Specific Heat Capacity
PART A : Mixing Temperatures
Aim:
To observe temperature changes when substances at different initial temperatures are mixed.
Method:
1. (a) Collect equal volume of hot water and tap water in two small plastic beakers. Measure and
record the volume and temperature of each.
(b) Predict the final temperature of a mixture of the two samples. Record your prediction with
reasons for the prediction.
(c) Mix the two samples of water into a larger beaker and record the final temperature reached.
(d) Was your prediction correct? Explain the result.
2. (a) Find and record the mass of a brass cube and measure out an equal mass of tap water into a
small plastic beaker (don’t put water onto the electric balance - think about the volume needed!).
Record the temperature of the water in the beaker.
(b) Collect some hot water in a small plastic beaker and place the brass cube in it. After a couple of
minutes, measure the temperature of the water (the cube and water will have reached thermal
equilibrium quite quickly because brass is a good conductor). Record the temperature if the cube.
(c) Predict the final temperature reached if the brass is placed into the beaker of tap water. Record
your prediction.
(d) Test your prediction quickly transferring the cube (using tongs) into the tap water and waiting
for the temperature to stabilize. Was your prediction correct? Explain your result.
3. Perform a similar experiment to that in part 2 above but this time add a very cold brass cube
(cooled in iced water) to a plastic beaker of tap water. Record all appropriate temperatures including
your prediction and reasons for the prediction. Test your prediction and comment on the result.
4. Discuss the conservation of energy in this experiment. How might some energy have been lost
from the apparatus used? (Describe the energy transfer processes contributing to this.)
CONCLUSION :
Explain the observation in Part A by considering the relative amount of energy possessed by the
equal mass samples of water and brass.
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PART B : Specific Heat Capacity of Metals
Aim:
To use simple calorimetric procedures to determine the specific heat capacity of several metals.
Method : (The Method of Mixtures)
Part A of this experiment highlighted some general observations but made little attempt to reduce
energy lost to the environment. In order to quantitatively measure the specific heat capacity of a
metal it is necessary to minimize energy lost and account for all energy transfers taking place in the
experiment. In Part B you will determine the specific heat capacity of a metal by equating the energy
lost by it (when added to water) to the energy absorbed by the water and the container holding it.
1. Measure and record the masses of a foam cup, brass cube and the foam cup after half filling it
with water. Also record the estimated uncertainty (+/-) for each reading.
2. Heat the cube by placing it in a plastic beaker of nearly boiling water as in Part A. Record the
temperature (including uncertainty) Just before you complete part 3 below.
3. Place the foam cup into its insulating block and quickly transfer the hot cube (without drops of
water) to the foam cup. Note the final equilibrium temperature of the system.
4. Repeat parts 1 to 3 above using another metal cube (eg. aluminium or zinc)
5. Use the conservation of energy relationship
Energy lost by
metal cube
= energy gained by
water
+
energy gained by
foam cup
to determine the specific heat capacity of the metal cube (look up specific heat capacity of water and
copper in a textbook).
6. Look up the specific heat capacity of the metals used in a textbook and compare them with your
experimental results.
7. For your calculations, determine the estimated absolute and relative errors in the final specific
heat capacity values obtained.
8. Discuss the sources of error in your experiment and explain whether it was really necessary to
include the energy absorbed by the foam cup.
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