LE CHATELIER'S PRINCIPLE

The objective of the experiment is to demonstrate how experimental conditions affect chemical equilibrium. The effect of the reactant concentration (CH3COO-) and the common ion addition (H+) on the reaction, which is given bellow, is studied.

3 Fe3+ + 6 CH3COO- + 2 H2O [Fe3(OH)2(CH3COO)6]+ + 2 H+

A solution of the complex [Fe3(OH)2(CH3COO)6]+ is an intense orange. A SpektraTM spectrometer can be used to evaluate the yield of the reaction: the higher the concentration of the coloured complex; the higher the absorbance of the examined solution.

On the basis of the activities presented here, Le Chatelier's principle can be introduced.

Hazards


Hydrochloric acid is corrosive, irritating to the eyes, the respiratory system and the skin. In the event of contact with the eyes, rinse immediately with plenty of water and seek medical advice.
R 36/37/38, S 26



Prepared by:
Nataša Gros, University of Ljubljana, Faculty of Chemistry and Chemical Technology