Kids, you can make a bubbly lemon, lemon-lime, or orange soda that is actually pretty tasty. You'll need a lemon, lime, or orange, and a glass, water, baking soda, and sugar. 

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

This is what you do: squeeze the juice from a lemon or orange into the glass. If you want the lemon-lime taste, add some juice from a lime to the lemon juice. According to how much juice you were able to get, add an equal amount of water. Stir in a teaspoon of baking soda, and observe what happens. Check out the taste, then add sugar if you like (or some other sweetener), tweaking the ingredients until it tastes perfect to you. Actually, any citrus fruit will do. If you happen to like grapefruit, you could also try one of these alone or in combination with one of the other fruits mentioned.

What's happening here? You are watching a gas being created by a reaction in-a-glass. The baking soda, or sodium bicarbonate (NaHCO₃ ), is reacting with citric acid from the juice to create carbon dioxide gas. This is why you need a citrus fruit for this experiment. All sodas get their fizz from trapped carbon dioxide (CO₂ ) bubbles, although it is usually added via pressurization. In other words, the bubbles in real soda are created by carbon dioxide gas that is added under pressure to a solution of water and a flavored sweetener, and that's all there is to soda-pop!

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Kathleen Carrado Gregar, PhD, Argonne National Labs 
[email protected]
October 1997

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Reference: Simple Science Experiments with Everyday Materials, by Muriel Mandell, 1989, Sterling Publishing Co., NY.