Flower Pigment Extraction: Anthocyanin pH Indicator

Project Overview: Red cabbage isn't the only plant hiding a natural pH indicator; flower petals are full of the same pigment, called anthocyanin. This project lets you extract color out of flowers and use it to test whether everyday substances are acidic or basic, all while exploring the same plant chemistry that gives flowers their vivid colors. 

Materials Required: 

1. A handful of dark-colored flower petals (red or purple petunias, roses, or hibiscus)

2. Rubbing alcohol

3. Hot water

4. A bowl

5. A strainer

6. 3 to 4 clear cups

7. Household liquids to test (vinegar, baking soda solution, lemon juice, soapy water)

Instructions: 

1. Tear the flower petals into small pieces and place them in a bowl.

2. Pour hot water over the petals, just enough to cover them, and let them steep for 15 to 20 minutes as the water takes on color.

3. Strain out the petals, keeping the colored liquid; this is your natural indicator.

4. Pour a small amount of the indicator into each of your clear cups.

5. Add a different household liquid to each cup and observe any color shift.

Congratulations, you just extracted a real plant pigment and turned it into a chemistry tool.

Fun Fact: Anthocyanins are the same pigments responsible for the color of blueberries, red cabbage, and even the deep reds and purples you see in autumn leaves, all controlled by the same simple pH chemistry you just tested.