![]() ![]() What is it about cabbage that causes this to happen? Red cabbage contains a water-soluble pigment called anthocyaninthat changes color when it is mixed with an acid or a base. Red cabbage juice is considered to be an indicator because it shows us something about the chemical composition of other substances. An indicator is typically a chemical that changes color if it comes in contact with an acid or a base.Īs you can see, the purple cabbage juice turns red when it is mixed with something acidic and turns green when it mixes with something basic. Scientists can tell if a substance is an acid or a base by means of an indicator. For reference, water (a neutral) has a pH of 7 on a scale of 0-14. Think of acids and bases as opposites - acids have a low pH and bases have a high pH. How does it work? Some substances are classified as either an acid or a base. The greener the strip turns, the more basic the liquid is and that is a video on that Scientific Experiment The redder the strip turns, the more acidic the liquid is. Dip the strips into various liquids to test their pH. Remove the paper from the cabbage juice and hang it up by a clothespin to dry. Try soaking some filter paper in concentrated cabbage juice. You might want to try orange juice, lemonade, milk, salt, ammonia, or soap. Use your cabbage juice indicator to test the acid or base properties of other common substances. Try adding each of the other “test chemicals" to a small amount of cabbage juice and note the color change to determine if the chemical is an acid or a base.Keep these two glasses of red and green liquid for future reference. Notice how the liquid turns green, indicating that this chemical is a base. In the second glass add a teaspoon of washing soda or laundry detergent.Stir with a spoon and notice the color change to red, which indicates that vinegar is classified as an acid. Since you know that vinegar is an example of an acid, add a little vinegar to the first glass of cabbage juice. ![]() Fill each glass half full with cabbage juice. Set out three glasses, side by side against a white piece of paper. ![]() Doesn’t cabbage juice smell great? Save the liquid for the experiments to follow.
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