Acid Or Base?

There are certain chemicals, called indicators, that turn different colors when they are added to acids, or to bases (acids' opposites). You can easily make an indicator out of something you might already have in your fridge - red cabbage!

What you'll need:
Red cabbage (fresh, not the kind in a jar)
Water
Lemon juice
Egg white
Baking soda
Vinegar
Cotton swabs
Small plastic cups
Plain white paper

Tear off a cabbage leaf and rub the dark red part onto the piece of paper until you see red marks. Make five spots, each about 1 inch (2.5 cm) in diameter. Pour a little of the water, lemon juice, egg white, and vinegar into four plastic cups. Dissolve about 1 teaspoon (5 mL) of baking soda in 1/2 cup (125 mL) of water in another cup. Dip a cotton swab into one of the liquids, then touch it to one of the red spots. Do this for all five liquids. What do you see?

Amazingly, the spots sometimes change color! The lemon juice and vinegar (both acids) turn it into an orange-red shade, and egg white and baking soda (both bases) make it greenish blue! Only water (which is neither an acid nor a base) doesn't cause a color change. The cabbage juice contains chemicals that act as indicator, and when they react with either an acid or a base, their atoms get rearranged into forms that have different colors. So if you have a liquid, but aren't sure if it's an acid or a base (or neither), you can test it with this indicator. Test a few other light-colored liquids to see what they are!