An important property of an object is its specific heat. All materials have a
specific heat, meaning that it is unique for each material. For example, the
specific heat of water is different than the specific heat of copper.
Specific heat deals with how quickly a
material heats up and cools down. Different
materials require different amounts of heat to
change in temperature. Water has a high specific heat, and so it takes a long
time for water to heat up/cool down as compared to, say, iron.
Physical Challenge
Following the explanation of the physical challenge, instruct the students to form teams
and proceed to the area where the exercise will be done.
Remind students that they will be using hot and cold water, and will be handling hot and
cold objects, and so should be careful. Also, explain how to properly use and care for the digital thermometers.
Each student team should choose someone to read and record data.
- Ask the students to gather in teams of 2-3.
- Each team should be given an appropriately sized cup that can hold enough water to
cover the object to be tested without spilling out any of the water.
- Each team should have access to a digital thermometer.
- Using the graduated beaker, ask each team to partially fill the Styrofoam cup
with tap water, being careful to measure the amount of water that is poured into
the cup.
- Record the volume of water that is in the cup.
- Using the digital thermometer, measure and record the initial temperature of the
water that is in the cup.
- Measure and record the initial temperature of your sample by measuring the
temperature of the water that is holding the sample.
- Using the tongs, remove your sample from the container and place it in the cup of
water.
- Immediately measure the temperature of the water in the cup and record it.
- Make several other measurements and record your measurements.
- When three temperature measurements are the same, stop measuring. The
equilibrium (final) temperature has been reached.
- When instructed to do so, place the sample in a container of hot water and allow it
to set for a few minutes.
- Repeat the above steps (2-11) for the hot sample.
- Write a short physical description of your sample, including shape, color, and
size.
- When all measurements have been done and all data have been recorded, empty
the cup and place the thermometer, cup, and sample in their appropriate places.
Be sure that they are dry.
- Clean up any splashes or spills and discard any waste.
- Return to the classroom to compute the specific heat of your sample based on
your two sets of measurements (cold and hot measurement data).
A downloadable version of these instructions can be found here:
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From the definition of specific heat (heat
change divided by the mass and change in
temperature), an equation can be derived
that shows how heat relates to changes in
temperature:
Q = m*c*∆T
We can use this to predict the results of
experiments by:
- Recording initial masses and temperatures of
objects
- Having those objects touch and recording their
final, stationary temperatures
- Using the change in temperature to solve for
heat change in one of the materials and set it
equal to heat change in the other material.
- Finally solving for specific heat.