Color Change Chemistry 3

Color Change Chemistry 3

On the second and first experiments, I used chemicals. But this time, I’m going to use grapes. Grapes contain a pigment molecule called flavin (an anthocyanin). This water-soluble pigment is also found in apple skin, plums, poppies, cornflowers, and red cabbage.

Things you’ll need: Black grapes, alcohol lamp, beaker, water, test tubes, test tube holder, vinegar, borax, a funnel, and a pipet.

  1. Put grapes into the beaker and fill it with water until it’s above the grapes.
  2. Set the alcohol lamp (you can use a stove instead of the lamp and a pot instead of a beaker).
  3. Wait until the water boils, then turn off the heat and let it cool.
  4. Use the funnel to take the grapes out.
  5. Pour vinegar into the first test tube. Pour water in the second. And pour water + borax into the third. Now we have acid to base.
  6. Drop 2-3 drops of the grape juice into the test tubes (if nothing happens keep adding the grape juice).

Very acidic solutions will turn anthocyanin a red color. Neutral solutions result in a clear color. Basic solutions appear in greenish-yellow. Therefore, it is possible to determine the pH of a solution based on the color it turns the anthocyanin pigments in grape juice.

Extra steps:

7. Pour the first and the third test tube together.

8. You will have the same colors.

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