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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- + 3SO42- + 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)