As demonstrated in the Make Carbon Dioxide experiment, acids and bases do not play well together. That experiment used vinegar and baking soda to create a reaction. In this experiment, the vinegar is replaced with something a little more mild (and tasty) – citric acid.
Citric acid is an acid found in citrus fruits like lemons, limes, grapefruits, and oranges, and in other fruits and vegetables like strawberries, raspberries, and tomatoes. It is a safe acid, and it’s what gives oranges, lemons, and limes their tartness. Different citrus fruits have different concentrations of citric acid. Lemons and limes have high concentrations, while oranges and grapefruits have lower concentrations. The higher the concentration of citric acid, the more sour-tasting a fruit will be. That is why lemon juice tastes sour and zingy while orange juice tastes sweet and tangy.
The Experiment
Supplies: an orange or clementine (cutie), some baking soda
What to do: Cut the orange into wedges or peel & separate into slices. Take a bite of the orange all by itself. Dip a second slice LIGHTLY into the baking soda. Take a bite. As you chew, it should start to bubble in your mouth. It might even taste like orange soda!
What is happening: Oranges and other citrus fruits contain citric acid. Baking soda is a base, the opposite of an acid. It is safe to eat but doesn’t taste very good on its own. As the citric acid and baking soda mix, it makes millions of carbon dioxide bubbles, the same gas you breathe out, and the same one that makes soda so fizzy.
Take it a step further: Try repeating this experiment using different fruits and vegetables. Compare what the flavors taste like and how fizzy the reaction is in your mouth. Did the juice fizz more or less that others you tried? Is there a relationship between how fizzy the bite with baking soda was compared to how sweet or sour the plain bite was?
Links
To see this experiment in action, head to YouTube and explore Science Fun for Everyone.