This is one of the kitchen science experiments that is definitely going to WOW your kids. And, if your kids don’t like to eat cabbage, they will at least fall in love with it to do some scientific explorations. For this science experiment, you create a pH indicator solution using red cabbage to measure the acidity and alkalinity of the various liquids. My kids loved testing the pH indicator of different solutions and had a wonderful time observing and learning about acid and bases.
- Red cabbage
- Baking Soda
- Lemon Juice
- Couple of glass cups
- dropper or pipette ( optional )
Red Cabbage pH indicator Science Experiment
- Finely chop some red cabbage leaves and place it in a bowl.
- Pour boiling water over them and keep it aside for 10 minutes.
- Strain the liquid from the cabbage mixture into a glass cup. It should be purple- violet in color. This is the ph indicator solution.
- Now, prepare the acidic and basic solutions for the experiment. Fill different glass containers with the following solution.
- Lemon Juice
- A teaspoon of Baking Soda mixed with water
- 2-3 teaspoon of sugar mixed with water
- Drop a couple of ph indicator solution( red cabbage water ) into each of the cup and notice how the color changes in each one of them.
- The color of each solution will change based on its pH level. It will transform into various shades of red in an acid, likewise for a base it will have various shades of green and, if neutral, a purple hue.
The science behind it
The pH scale is an important indicator of how acidic or alkaline a solution is. The scale ranges from 0 to 14, 0 being the strongest acid, 7 being neutral, and 14 being the strongest alkali.
Red cabbage is a perfect pH indicator because its leaves contain a pigment called anthocyanins that are responsible for many of the red/purple/blue colors found in fruits and vegetables. Anthocyanins molecules change color depending on the pH of the solution they are in, making them useful as a pH indicator.
By placing the red cabbage in boiling water, we extracted the pigment molecules into the water solution. When mixed with various solutions such as vinegar, lemon juice, baking soda solution, it changes color depending on the pH of that solution. The color found in neutral solutions is purple. The effect is a red color as the solution becomes more acidic. Increasing the pH in basic solutions change the color from blue to green and the solution is found to be greenish-yellow at high pH.
You may also use red cabbage juice to create paper pH indicator strips. To make pH indicator strips, cut some strips from a clean coffee filter paper. Let the strips sit in red cabbage juice for a while. Eventually, remove the strips from the juice and allow them to dry completely. They should be light purple or light blue in color. Once the strips are completely dry, you can use them to test the pH indicator of different solutions. Just dip the strips into the solution you want to test, remove it and look for a change of color. The acidic solution will make the strips red and the bases will turn them green.
I hope you’ve had fun making beautiful colored solutions in the red cabbage pH indicator science experiment. If you are looking for more science experiment, then check out some of them HERE.
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