The perfect science experiment for kids of all ages, this fizzy color changing chemical reaction is sure to amaze. Easy experiment with nontoxic materials.
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Kids can’t resist this amazing color changing chemical reaction. It fizzes. It transforms. It works over and over again. It’s completely nontoxic, made with materials you probably have in your kitchen. I can’t wait for you to dive in and do it for yourself!
This is hands-down one of our favorite science experiments to date. It left my five-year-old saying, “I want to be a chemist when I grow up!” and my three-year-old saying, “I love science!” Those are some pretty sweet things for a mama chemist to hear.
The chemistry and the first part of the instructions are the same as our experiment Make Your Own pH Indicator Using Red Cabbage where we turned different liquid solutions purple, blue, and pink, depending on their pH! I actually saved a part of the cabbage juice from that experiment for this experiment.
Color Changing Chemical Reaction Directions
Total Time: 40 minutes to prepare the indicator, two hours to let it freeze; 10 minutes to carry out the rest of the experiment (though you will probably be repeating this over and over again!)
Difficulty: This one definitely requires the aid of an adult to prepare the indicator, unless you trust your child with a sharp knife and a hot saucepan full of boiling cabbage (I don’t, personally). It’s pretty easy, though, as far as actual skill goes.
Materials You Need:
One half of a head of red cabbage
Ice cube tray
Tall clear cups
Plastic Pipettes, if desired
To make the indicator solution:
- Chop up your red cabbage into small pieces. Place 2-3 cups in a saucepan and cover with water.
- Bring the solution to a boil and then turn off the heat. Let it sit for about 30 minutes to cool down.
- Pour the cabbage water through a strainer into a jar or large measuring cup. The dark purple liquid in the jar is your indicator.
- Mix the cabbage water with enough baking soda to turn the solution bluish-green. You will probably need a few tablespoons, no need to be exact.
- Pour this liquid into the compartments of an ice cube tray. Freeze for a couple of hours to make ice cubes.
Why does the red cabbage juice turn bluish-green when mixed with baking soda? Hint: Refer to my original post to find out!
Fizzy Color Changing Chemical Reaction Experiment:
- Dump out the indicator ice cubes into a baking tray or casserole dish.
- Fill a cup with vinegar. Using a plastic pipette, squirt the ice cubes with vinegar and watch what happens. Do the ice cubes fizz? Do the ice cubes change colors?
- Now for the REALLY fun part. Place an indicator ice cube into a cup of vinegar. What happens? You may want to place your cup in the baking tray just in case it overflows! Add more ice cubes to your cup of vinegar. What color is your solution now?
The Science Behind the Color Changing Chemical Reaction
So, what is going on here? Well, a couple of things.
First, the fizzy part. This is a simple reaction behind baking soda and vinegar. The old classic! Since the ice cubes contain baking soda they react with the vinegar in the glass to produce carbon dioxide bubbles: the fizz that you see and love.
Next, the color changing part. You start out with bluish-green ice cubes. You end up with bright pink vinegar. As you add more ice cubes the solution gets darker and darker and eventually turns purple. It’s really cool!
The color changes because the pH changes and red cabbage is a natural pH indicator. pH is a measure of how acidic or basic something is. Baking soda is basic, so the red cabbage juice turns bluish-green when mixed with it. Vinegar is acidic, which makes the red cabbage juice turn pink! As more baking soda is added to the vinegar the solution becomes more neutral, which is why it turns purple. Read my original post for more details and more ways to experiment and play with red cabbage juice. We even dyed eggs with it this year!
I hope your kids love this experiment as much as we do! I had so much red cabbage juice I actually made a whole bunch of indicator ice cubes that I pull out once in awhile. This experiment is so easy to do and to clean up, plus it is so exciting for the kids to see the fizz and the color change! It makes a dull afternoon at home exciting and educational. 🙂 Enjoy!