Informal experiment 1: Le Chatelier’s principle


Informal experiment 1: Le Chatelier’s principle


To determine the effect of a change in concentration and temperature on chemical equilibrium


0,2−3 purple CoCl2 in ethanol solution, concentrated HCl, water

test tube, tongs

ice-bath, water-bath, hot-plate or bunsen burner


Place the water bath on the hot-plate and heat.

During each step observe and record the colour change that takes place.

Put 4 – 5 drops of 0,2−3 CoCl2 solution into the test tube.

Add 10 – 12 drops of water.

Add 20 – 25 drops of concentrated HCl.

Place the test tube in the water-bath on the hot-plate (use tongs). Leave for 1 – 2 minutes. Record your observations.

Place the test tube in the ice-bath. Leave for 1 – 2 minutes. Record your observations.

The equation for the reaction that takes place is:




Chipa Thomas Maimela‘s insight:


Complete your observations in the table below, noting the colour changes that take place, and also indicating whether the concentration of each of the ions in solution increases or decreases.


Table 1 Original colourFinal colour[CoCl2−4][Co(H2O)2+6][Cl−]Add HCl     Add H2O     Increase temp     Decrease temp


Use Le Chatelier’s principle to explain the changes that you recorded in the table above.

Draw a conclusion about the effect of a change in concentration of either the reactants or products on the equilibrium position.

Also draw a conclusion about the effect of a change in temperature on the equilibrium position.

See on


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