Oscillating Belousov-Zhabotinsky Chemical Clock Simulation

45 mins Ages 10-14 Indoor

A challenging, hands-on discovery and STEM project designed for curious young minds aged 10 to 14.

Materials Needed

  • • 1000 mg Vitamin C tablet (1 tablet)
  • • Tincture of iodine (2%) or povidone-iodine (1 small bottle)
  • • Hydrogen peroxide (3% household) (1/4 cup)
  • • Liquid laundry starch or cornstarch slurry (1 teaspoon)
  • • Clear glass tumblers and measuring cups (2 units)
  • • Safety goggles and stopwatch (1 set)

Pro Tips

  • → Prepare Solution A (vitamin C, iodine tincture, and water: turns clear) and Solution B (hydrogen peroxide, liquid starch, and water).
  • → When mixed, vitamin C quickly consumes free iodine, keeping the liquid clear.
  • → Once the vitamin C is completely depleted, free iodine accumulates instantly, binding with starch to turn the solution deep blue-black in a fraction of a second.

Safety First

Wear safety goggles; handle hydrogen peroxide with care. Do not ingest chemicals.

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Step-by-Step Instructions

1

Step 1

Crush a 1000 mg Vitamin C tablet, dissolve in 60 mL warm water, filter the sediment, and stir in 5 mL iodine tincture until the liquid becomes clear (Solution A).

2

Step 2

In a separate glass, mix 60 mL warm water, 15 mL hydrogen peroxide, and 2 mL liquid laundry starch (Solution B).

3

Step 3

Pour Solution A into Solution B, swirl back and forth once to mix, and start a stopwatch.

4

Step 4

Watch the clear liquid remain colorless for roughly 45–60 seconds, then snap to an opaque blue-black color.

What they are learning

Chemical kinetics and reaction rate constants Competing oxidation-reduction reactions Triiodide-starch complex equilibrium