The Red Cabbage Juice Science Experiment

 We have gotten behind on doing our science experiments, as Desert Boy has repeatedly reminded me. So we finally made time this week to do the red cabbage juice experiment. I had bought red cabbage months ago, and we ate half of it. The other half has been sitting in the refrigerator for months. Fortunately red cabbage keeps really well.

The Red Cabbage Juice Indicator Experiment
Red cabbage juice contains flavin (anthocyanin), which is an indicator of pH. If something acidic (low pH) is put in the red cabbage juice, it turns pink. Something basic (high pH) makes it turn greenish. Something neutral (around pH 7) leaves it purple. (pH is measured on a scale of 1 to 14).

Step 1: Boil a small pot of water (about 2-3 cups) and put cut red cabbage in the water. Boil for 10 minutes. Then strain and keep the juice.

Step 2: Get four test tubes (or glasses or jars). Find some common household ingredients. We chose vinegar, lemon juice. washing soda and baking soda.

Step 3: Have the kids make a hypothesis of which items are basic and which are acidic. Remind them of what color acids and bases will make the cabbage juice turn.

Step 4: By this time the cabbage juice should have cooled enough that you can pour it into your test tubes. Don't fill them too high.

Step 6: Add a little of your first ingredient to the cabbage juice. We found a funnel to try to minimize the mess.

Step 7: Watch what happens. If the color doesn't change, add a little more. You might need to stir. You also might need to lift a little water to see what tint it is.

Step 8. Repeat steps 6-7 with all your ingredients, seeing if your hypotheses are correct.

 The kids were really good at taking turns pouring in our test liquids and powders. They were very excited because it felt like real science to them. (Test tubes are pretty awesome that way!)

 We ended up with vinegar and lemon juice turning our cabbage juice pink and washing soda and baking soda making the water greenish.

It was so much fun, and we had enough cabbage juice left over, that we decided to do our experiment again with different ingredients.

 This time around we used apple juice, milk, salt, and cream of tartar. Any guesses on what pH these have?

This was a fun, simple experiment. And since we didn't knock it over, the clean-up time was minimal.