Demonstration 1: Metal-Acid Reactions
This demonstration illustrates that most active metals replace hydrogen from an acid.
- Materials
6 M Hydrochloric acid, HCl
Small samples of any four metals (Cu, Mg, Al, Zn, Fe, or Sn)
Slant-top overhead apparatus or petri dishes (or 50-mL beakers or titer plates)
- Safety
6 M HCl is corrosive and must be handled with care. Goggles should be worn.
- Directions
Place vessels on an overhead projector. Add 6 M HCl to each vessel, followed by the sequential addition of the metal samples. Observe; ask students to explain the results.
Demonstration 2: Nature of Indicators
Many common foods have natural indicators.
- Materials
Natural Indicators: Red cabbage juice, grape juice, or fillings from berry fruit Pies
Vinegar
Baking soda (sodium bicarbonate), NaHCO3
6 Petri dishes, slant test tube apparatus, or 50-mL beakers.
- Safety
Most of the materials are very weak acids or bases, but goggles should still be worn.
- Directions
Place natural indicators in each of three dishes, test tubes, or beakers. You might want to dilute the fruit fillings with a little distilled water and use the resulting mixture as the sample. Add vinegar to one solution, add baking soda to another, and use the third as a control. Have students make observations and state their conclusions.
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