Experiment 1 : Heat Energy

Question: How much heat energy is in a substance?

Background: The foods we eat give off different amounts of heat energy. Other substances also give off different amounts of heat energy when they burn.

Materials: cork, matches, needle, thermometer, test tube, test-tube holder, assorted substances (bread, bacon, potato, paraffin, piece of cloth, piece of wood, wad of paper).

Procedure: Place 50ml of water in a test tube. Measure the temperature of the water with a thermometer. Take a small sample of bread and stick it to the blunt end of a needle. Stick the needle with the bread in a cork. Put the cork on a tabletop. Use a match to set the bread afire. Once ignited, hold the test tube with water above the flame. CAUTION: Be careful when you are working with an open flame. When the flame goes out, measure the temperature of the water in the test tube. Keep a record of this temperature. Repeat the procedure for each substance.

Upon completion, answer these questions:

• Which substance caused the greatest change in the water temperature?
• How many calories of heat did each substance give off? (Hint: Multiply the change in water temperature by 50).
• Which substance gave off the greatest amount of calories per gram?
• What is the reason for not igniting the substance with the match while it was under the test tube?

Experiments 1-2 are based on experiments found in the following sources:

Bernstein, L. (1999). Globe Biology. Upper Saddle River: New Jersey, 671pp.

Magnoli, M.A., Shymansky, J.A., Blecha, M.K, Holly, J.C. (1985). Experiences in Physical Science. Laidlaw Brothers: A Division of Doubleday & Co., Inc., 592pp.

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