Instant Color Change Experiment | Iodine Clock Reaction



Introduction: Instant Color Change Experiment | Iodine Clock Reaction

In this project, we will turn almost clear liquid into the dark in the blink of an eye. It takes a little preparation, and possible trip to the pharmacy, but it's worth it.

Step 1: So Here's What We Need

  • 2 transparent glasses
  • 2 small plastic cups
  • Any container with warm water
  • Spoon for stirring
  • Potato or corn starch
  • 1 gram of Vitamin C
  • Tincture of iodine
  • Hydrogen peroxide (3%)
  • Syringes for exact dosing

Vitamin C, tincture of iodine, hydrogen peroxide and syringes are sold in any drugstore.

Vitamin C can be also purchased on

Step 2:

Place 1 gram of vitamin C in a plastic cup and add 60 ml of warm water. The syringe will help to accurately measure the required volume.

Stir well to dissolve the powder completely.

Step 3:

Next, prepare the liquid starch.

Mix 1 teaspoon of starch in a little cold water. Then add hot water and stir again.

The total amount to be 150 ml.

Step 4:

Pour 60 ml of warm water in each glass.

Step 5:

In the first glass, add 5 ml of tincture of iodine and 10 ml of solution with vitamin C.

Note that iodine became transparent.

Step 6:

In a second glass mix 15 ml of hydrogen peroxide and 5 ml of liquid starch.

Step 7: Preparation Is Over, Time to Move on to the Fun Part

Take 2 glasses and pour all the liquid from one glass to another. Do this several times. Put the glasses on the table and watch.

Be patient... It may take a few seconds to a few minutes before the liquid will change its color to dark.

Watch the video:

This experiment is a chemical reaction called "Iodine Clock".

Roughly speaking it's a battle between the starch, which is trying to turn a dark color of iodine, and vitamin C, which does not do it. Finally, vitamin C is completely consumed and the result is instant color change.

By the way, if you add vitamin C, the liquid becomes colorless again.

This is one of the most simple, but at the same time the most impressive experiments. Try it yourself!

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