Chemistry Honors/AP

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Laboratory Exercise

#### Goal: Determine the specific heat of a metal. Note that in order to complete this expermiment, you must have done the previous experiment to determine the calorimeter constant.

Materials and Equipment:

• Your calorimeter (cups, beaker, lid, thermometer) from last experiment.
• Pot for heating water
• Metal sample. The easiest to use is copper pennies (pennies dated before 1962). Each penny is approximately 11gm.

#### Procedure

1. Reassemble your calorimeter and put 100 mL of cool water in the cup. (If you use a different amount, convert to mL). Record the amount as mw.
2. Stir until a constant temperature is reached. Record this temperature as Tw.
3. Put 1 quart of water in your pot
4. Determine the mass of your metal sample to the nearest gram or better. (Use your scale if you can reassemble it!). If you use coins, be sure that you check the mint dates. Coins minted after 1981 may be "sandwiched" with a layer of zinc. Record the amount as ms.
5. Add your mass of dry metal to a heat-proof small jar, test tube, or boil proof bag. Close the container.
6. Place the container in the pot of water, and bring the water bath to a boil. Heat the metal 10-15 minutes this way.
7. If you have a second thermometer, determine the temperature of the hot water bath. Otherwise, assume that it is 100 °C. This is Ts
8. Remove the container using tongs or water-proof heat gloves, quickly open it and dump the dry hot metal into the calorimeter water. Don't get any water from the sides of the metal container in your calorimeter!
9. Close the calorimeter quickly, and stir constantly. Record the highest temperature reached as Tf.

#### Examining the results

Determine the change in temperature of the water as Tw -Tf = Twf.

Determine the change in temperature of the metal as Ts -Tf = Tsf.

The calorimeter constant you calculated previously is B. The heat capacity of water (Cw) is 1.00 calorie/gK.

The heat capcity of your metal sample is

C = - Twf * (B - mw* Cw)/ms * Tsf.

Report

Your lab report should include a description of the materials and equipment used, and your procedure, as well as the data taken and calculations for at least one metal sample. Try repeating the experiment with different amounts of the same sample, or with different samples.