What you need:
- Grape juice
- White vinegar
- Baking soda
- Drinking glasses
What to do:
Pour about ¼ cup of grape juice into a glass.
Add about ½ teaspoon of baking soda to the grape juice. What happened? Here, it may help to have a second glass of plain grape juice to compare.
Now add a couple splashes of vinegar to your mixture. What happened?
What’s going on?
Grape juice is an indicator – it changes colour depending on whether it’s mixed with an acid or a base. Many children are familiar with the term acid and may think that all acids are dangerous. However, there are many acids that are perfectly safe – vinegar is one example. A base is the opposite of an acid. When we add a base (baking soda) into the grape juice it changes to a blue colour. Then, since acid is the opposite of a base, adding vinegar ‘cancels out’ the baking soda and turns the grape juice back to its original colour. When vinegar and baking soda react, they also make bubbles!
There are other common, safe acids and bases found around the house. Try adding dish soap to see if it is an acid or a base. Does lemon juice cancel out the dish soap? What about laundry detergent and Sprite?
Here at TELUS World of Science - Edmonton we do this experiment using plastic test tubes and pipettes. In this setting, young children can role-play being a chemist while practicing their fine motor skills.