A color - oscillating reaction !

Do you want to impress your colleagues in your lab between two experiments ?

With hydrogenperoxyde (30%), potassium iodate, malonic acid, manganese (II) sulfate monohydrate, sulfuric acid and starch, you can transform your beaker into a spotlight changing color as in discotheque !

In fact, you first have to prepare three different solutions :

Solution A:   410 mL of 30% hydrogenperoxide are diluted to 1.0 liter with distilled water in a 1500 mL beaker.

Solution B:   43 g of potassium iodate are dissolved in about 800 mL of dist. water + 4.3 ml of conc. sulfuric acid in a 1500 mL beaker. The mixture is made up to 1000 mL with dist. water 

Solution C:   16 g of malonic acid and 3.4 g of manganese (II) sulfate monohydrate are dissolved in about 500 mL of dist. water in a 1500 mL beaker. 3 g of soluble starch are dissolved in 100 mL of boiling dist. water in a 150 mL beaker. The starch solution is poured into the solution of malonic acid and manganese sulfate. The mixture is diluted with dist.water to 1000 mL.

Then, add 250mL of the solution B with the same volume as the solution A into a cristallyzing dish. After having stirred vigourosly with a magnetic stirrer, pour the solution C with the others still stirring, and just see what's happening !

Oscillating_Chemical_Reaction_Briggs_-_Rauscher

Your cristallizing dish is going to turn yellow then blue, the colorless. It will oscillate during 5-10 minutes.

This reaction is called Briggs - Rauscher reaction. The three colors observed are a result of an increase in
the concentrations of I2 (yellow), starch-iodine complex (blue), and I1- (colorless).

Of course, you have to take care when making this experiments, sulfuric acid burns and KIO3 is and oxidizer ! Moreover, some products can be toxic, so don't forget to wear gloves and glasses !