The reaction between cupric chloride solution and aluminum foil is a very quick and simple labette to introduce a variety of topics in chemistry.
The reaction provides a very distinct set of observations that allow students to understand evidence that shows a chemical reaction is taking place. The reaction gives off heat (exothermic reactions), obvious color changes, release of gas (bubbling and condensation), deterioration of the aluminum as it recombines.
The chemical activity is quite unique as there are several reactions taking place. First the cupric chloride ionizes in the water producing the nice blue color from the copper inons in solution. Most aluminum foil has a layer of aluminum dioxide which reacts with chloride ion to liberate the oxygen and create aluminum chloride. The copper ion reacts with water to form copper hydroxide and release hydrogen. The bubbling is caused by the both hydrogen and oxygen gas which recombine to condense on the cooler surface of the mouth of the test tube.
I have the students complete this labette multiple times throughout the year as a common thread tying together many different topics in the chemistry curriculum.
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