This project teaches you how to create a natural pH indicator by boiling red cabbage. You will then use this indicator to test the pH levels of various household liquids, which will change color depending on whether they are acidic, neutral, or basic.
If red cabbage juice is used as a pH indicator, then acidic drinks like soda and orange juice will turn the indicator red or pink, while neutral or basic liquids like water and milk will result in a purple, blue, or green color.
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With adult help, chop the red cabbage and boil it in the saucepan with water for about 10-15 minutes.
Let the solution cool, then strain the liquid into a jar. This purple liquid is your pH indicator.
Pour a small amount of each drink you want to test into a separate clear cup.
Add a few drops of the red cabbage indicator to each cup.
Observe and record the color change for each liquid.
Arrange the tested liquids in order from most acidic to most basic based on their color.
You can create a pH color chart by testing known acids (like vinegar) and bases (like baking soda solution).
The red cabbage juice will change color in response to the pH of the substance it is mixed with. In acidic solutions (pH < 7), it will turn red or pink. In neutral solutions (pH = 7), it will remain purple. In basic (alkaline) solutions (pH > 7), it will turn blue, green, or even yellow.
The type of drink being tested.
The color of the red cabbage indicator.
The amount of indicator used, the amount of each drink, and the temperature.
An adult should handle the boiling water. Do not drink any of the test solutions. Label all cups clearly.
Create a vibrant display with your tested samples, showing the full spectrum of colors.
Develop a large pH scale poster with your cabbage indicator color chart.
Explain the science behind anthocyanins, the pigment in red cabbage that changes color with pH.
