Iodine Clock Reaction

Materials

3 500mL Erlenmeyer Flasks with Stir Bars

3 Stir Plates

6 Bottles of Solutions (Mix 1 with 2, 3 w/ 4, and 5 w/ 6)

Gloves and Goggles

Solutions

• Solution A: 2gm KIO3 in 1 liter H2O
• Solution B: Dissolve 2gm soluble starch in 500ml boiling water,
•                    add 0.4gm NaHSO₃ + 5ml 1.0M H₂SO₄,
                     then bring up to 1 liter.

Procedure

1. Mix equal volumes A + B with stirring.
2. Varying volumes gives different times.
   1. 1) 160ml A
      2) 160ml B
   2.     
   3. 3) 80ml A + 160 ml H₂0
      4) 80ml B
   4.      
   5. 5) 40ml A + 240ml H₂0
      6) 40ml B
3. Mixing 1 + 2, 3 + 4, and 5 + 6, gives relative times of 1, 0.5, 0.25.

Reactions

IO₃^- + 3HSO₃^- --> I^- + 3SO₄^2- + 3H⁺

6H⁺ + IO₃^- + 5I^- --> 3I₂ + 3H₂O

I₂ + starch --> (blue)

Waste Management

The solutions should be collected in a bottle and sent to EH&S as Hazardous Waste (Toxic)