What You Need:
- Clear plastic cups - 3
- A Vitamin C tablet - 1,000mg or 2x500gms (available at a chemist)
- Tincture of iodine (2%, available at a chemist )
- Hydrogen peroxide (3%, available at a chemist )
- Laundry starch
- Safety goggles
- Measuring cup
- Powder the Vitamin C tablet by placing it in a plastic bag and crushing it with a rolling pin.
- Put all the powder in a cup and add 60ml of warm water. Stir for at least 30 seconds. The water may become a little cloudy. Label this cup as 'A'.
- Now add 1 teaspoon of the liquid from A to a new cup. Add to it 60ml of warm water and 1 teaspoon of the iodine. The brown colour from the iodine will immediately disappear. Label this cup as 'B'.
- In the last cup, mix 60ml of warm water, 1 tablespoon of hydrogen peroxide and 1/2 teaspoon of liquid starch. Label this cup as 'C'.
- Now pour all of B into C. Pour them back and fourth between the 2 cups a few times. Place the cups down and observe. In a few seconds the liquid will suddenly turn dark blue!
What you just witnessed is called a clock reaction. You can change the amount of time it takes for the liquids to turn blue by using different kinds of starch--you can use rice starch instead of laundry starch and measure the difference in time. The starch turns the iodine blue but the Vitamin C keeps it from turning blue.