Heat Capacity of Mozzarella

Purpose:

To measure the heat capacity of mozzarella cheese as a function of its temperature.

Equipment:

Calorimeter, thermometer, heater, glass beaker, stopwatch, ~ 200 gm of water, ~100 gm of mozzarella cheese.

Procedure:

The calorimeter consists of an aluminum cup that fits into a larger outer container supported by an insulating ring. A cover, with a hole and stopper to accommodate a thermometer, fits onto the top of the outer container.

  1. Heat about 200 gm of water in a glass beaker to appoximately the temperature specified by the instructor. (Each group will start with a different water temperature.)

  2. Determine the mass of the mozzarella and measure its temperature. The cheese should be near room temperature.

  3. Determine the mass of the inner aluminum cup.

  4. When the water is near the specified temperature, pour it into the calorimeter cup and quickly replace the cover. Allow the aluminum cup to warm up (a few seconds) and record the temperature.

  5. Quickly place the cheese into the cup, start the stopwatch, and record the temperature of the mixture every 30 seconds for the next five minutes. You may gently stir with the thermometer between readings.

  6. Clean out the Al cup when finished. The addition of some boiling water will help get the cheese off the bottom!

Report

Recording the temperature for five minutes will allow you to more accurately determine the "final" temperature of the mixture. It will take time for the cheese, water and aluminum cup to reach equilibrium. Some heat will be lost from the calorimeter during this time.

  1. Create a plot of temperature vs time and examine it. The first few datum may be erratic, but the points should eventually reveal a nearly straight line. Ignoring the erratic points, extrapolate the temperature to time = 0. This should provide a good estimate of the "final" temperature of the mixture, had equilibrium been reached quickly before any heat could escape.
  2. Using conservation of heat energy, determine the specific heat of the mozzarella. Do not forget to include the aluminum cup (c= .22 cal/goC) in your calculations. (It will be more accurate to determine the mass of the water by subtracting the masses of the mozzarella and the empty cup from that of the cup + contents.)

Conclusion:

The specific heat determined by each group, as well as the temperature ranges for their specific experiment, will be posted on the board. Be sure to record those values before leaving the lab. In your conclusion, estimate and discuss the errors in determining your group's value for the specific heat.
Analyze the specific heat values determined by all groups to determine whether or not there are any trends related to the temperatures at which the experiments were performed? You may wish to try various plots to help quantify those trends.