Thanksgiving is just around the corner! Do you, like many people, enjoy cranberry sauce, relish, or jelly at your Thanksgiving meal? Did you know that the Pilgrims may well have eaten cranberries at the first Thanksgiving? This experiment explores a special property of cranberries.
Cranberries contain anthocyanin, a pigment that changes color when it reacts with an acid or a base. Cranberries, which have a tart taste, are naturally acidic. The anthocyanin in the cranberries reacts with the acid in the berries and makes them red. In this experiment, you will use cranberry juice as a natural indicator to determine whether other substances are acids or bases. Knowing that anthocyanin reacts with the acid in cranberries to make them red, do you have a hypothesis for what will happen when another acid is added to the cranberry juice? What if a base is added?
Cranberry juice (100 percent juice)
All you have to do is add a little (a tablespoon or so) of the lemon juice or other substance being tested to the cranberry juice and observe. Is the result what you expected? Or do you need to revise your hypothesis?
Once you have tested each of the substances, you can try adding two different substances to cranberry juice and test whether the order in which they are added makes a difference. For instance, what happens if you add baking soda and then add lemon juice? What if you add lemon juice then baking soda? What if you add them at the same time?