Hg-1 Chemical Clock A+B
Published: Wednesday 06 June 2007 - Updated: Monday 28 March 2011
To demonstrate a cyclic chemical reaction, the Belousov- Zhabotinskii reaction.
- 3 1L flasks
- Overhead Projector
- Disposable pippetes
- Solution A 0.23M KBrO3 (Potassium Bromate)
- Solution B 0.31 Malonic acid & 0.059M (Potassium Bromide)
- Solution C 0.019M ammonium cerium (IV) nitrate & 2.7M sulphuric acid
- Solution D 0.025M ferrion sulfate
Chemical Clock A
Chemical Clock B
To make Solution A:
Dissolve 38.41g of Malonic acid in 400-600ml of water
Stir then add water in a volumetric flask to make 1L
To make solution B:
Dissolve 32.26g of Malonic acid in 400-600mL of water
Add 7.021g of potassium bromide
Add water to make 1L of solution in a volumetric flask.
To make solution C:
Dissolve 10.412g of ammonium cerium (IV) nitrate in 400mL of water. Stir
Add 150mL of concentrated sulphuric acid slowly as solution will heat up
Stir and allow to cool to room temperature.
Add water in a volumetric flask to make 1L of solution.
Solutions will store in sealed containers for a few weeks without degradation.
Solution D is off the shelf:
In a 1 Litre Flask add 300mL of solution A to 300ml of solution B.
Wait until solution clears.
Add 300mL of solution C.
Wait till solution fades to yellow Cerium colour
Add 3.6mL of solution D.
The chemical clock reaction should commence with the solution cycling through green purple red blue and back with about an initial 60 second total cycle time.
Add 2.5mL of Solution A and 2.5mL of solution B to a Petri dish
Add 2.5mL of solution C to the dish
Add 1mL of solution D
Concentric rings should develop after 1 minute.
Chemicals A, B and C can be prepared and stored for up to a year in sealed containers.