1. Sulfuric acid plus sugar. Fill a plastic cup half full with sugar. Add 40 ml of concentrated sulfuric acid. Stir well and stand back. This experiment can be used to illustrate a decompostion reaction since the sucrose decomposes into carbon dioxide and water. The sulfuric acid acts as a strong dehydrating agent. Do this in a hood because fumes from the sulfuric acid will be produced..
2. Caloric content of candy. Fill a big test tube about one quarter full of sodium or potassium chlorate. Heat until melted. Add candy. Hard candy works very well. This experiment is useful when covering calorimetry and thermochemistry. It shows the tremedous amount of energy candy contains. Use a shield.
3. Place a small amount of water in an aluminum soft drink can. Heat the can and contents until the water is boiling vigorously. Using tongs dip the can upside down into a trough of cold water about 1 inch deep. Great when covering the gas laws and air pressure.
4. Etch the inside of a soft drink can with a file about halfway down the can to remove the protective inside coating. Fill the can with 1 M CuCl2 and allow to stand for a few minutes. Remove the solution and rinse the can with water. The can can be easily pulled apart. When oxidation-reduction is the topic use this as an introduction. The Cu2+ in the solution acts as an oxidizing agent and oxidizes the exposed aluminum by dissolving and replacing it on the can. The copper that plates out has little strength.
5. Mix 50 ml of concentrated HNO3 and 100 ml of concentrated H2SO4 in a beaker. Add 5 to 10 cotton balls and put the beaker in an ice bath in a hood. Allow to soak overnight. Wash the cotton thoroughly the next day and allow to dry. The cellulose in the cotton has been converted to nitrocellulose. Touching the cotton with a hot object will cause the cotton to ignite and turn completely into a mixture of gases so it seems to disappear.
Many concepts are illustrated by the above demonstrations.
All of the experiments should be done while using goggles and the
usual safety precautions taken.
Tim Allen
Fletcher High School
Neptune Beach, FL.
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