Description

is pink in aqueous solution and is blue. The equilibrium between these two species can be disturbed by adding ions and by changing the temperature. The changes in the equilibrium position are as predicted by Le Chatelier's principle.


Apparatus

Six boiling tubes and a rack.

One 100cm measuring cylinder.

Three 250cm beakers.

Two dropping pipettes

Access to a top pan balance.

Chemicals

The quantities given are for one demonstration.

4g cobalt(II) chloride-6-water -

100cm of concentrated hydrochloric acid.

About 200cm of crushed ice.



Method

Before the Demonstration

Boil a beaker of water and prepare a beaker of crushed ice and water.

Dissolve about 4g of cobalt(II) chloride-6-water in 40cm of water. A pink solution containing will be formed.