Chemistry

10. Study of an ‘iodine clock’ reaction

  • 00:24 Why is it important to keep each volume the same?
  • 00:55 Why is it not important to be exact when measuring the starch volume? 
  • 01:08 What is the hydrogen peroxide reacting with?  
  • 01:01 What is being produced as the hydrogen peroxide reacts? What other reaction is also occurring?
  • 01:15 Why has the colour changed?

  • de-ionised water

  • stopwatch

  • 4 x 10 cm³ measuring cylinders

  • 25 cm³ volumetric pipette with safety filler

  • 50.0 cm³ burette and funnel 

  • clamp and stand 

  • 5 x 250 cm³ conical flasks

Hazard Risk Control measure

0.1mol dm-3 H2O2 solution

Contact with eyes and skin

Eye: flood with tap water (10 min)
Skin: flood with plenty of water

1mol dm-3 H2SO4 solution

Contact with eyes and skin

Eye: flood with tap water (10 min)

Skin: flood with plenty of water

0.1mol dm-3 KI  solution

Contact with eyes and skin 

Eye: flood with tap water (10 min) 

Skin: flood with plenty of water 

0.005 mol dm-3 Na2SO3 (but producing SO2 gas which is toxic)

Produces SO2 – Toxic

 

Flood with water.                                                 

Avoid inhaling gas from solutions – move to get fresh air.                                                                       

Call doctor if difficulty breathing