A note before you begin this experiment: be sure an adult is present and make sure you’re using safety goggles. Iodine tincture stains very easily, and hydrogen peroxide is harmful to eyes and skin.
Most of the ingredients for this experiment can be found at your pharmacy.
What you need:
1000 mg vitamin C tablet
Iodine tincture (2%)
Liquid laundry starch
What to d0:
Makes sure you’re wearing your safety goggles. You’ll need to make three liquids for this experiment.
Crush 1 vitamin C tablet into a fine powder. Using a plastic baggie and a spoon will help. Put it in a clear, empty cup.
Add 2 oz. of warm water
Stir until vitamin C tablet is dissolved. It’s OK if the water is cloudy.
In another clear empty cup, add 2 oz. warm water
Add 1 tsp. of Liquid A
In a third clear empty cup, add 2 oz. warm water.
Add 1/2 tsp of hydrogen peroxide
Now for the fun part! Pour all of Liquid B into Liquid C. Pour back and forth between the two cups a few times. Then set the cup down and wait. In a few seconds, the clear solution will turn dark purple.
This rapid color changing experiment is also known as the iodine clock reaction. It’s called a clock reaction because you can change how long it takes for the solution to change color based on the amount of each chemical you add.
The liquid turns dark purple because of the liquid starch and iodine. The vitamin C stops the solution from turning blue, but eventually when it’s used up in the reaction, the solution finally turns blue.