Le Chatelier’s Principle Using a Cobalt Complex
Co(H2O)62+, which is pink in color, is converted to a blue CoCl42- complex through the addition of NH4Cl. The resulting blue liquid is separated from undissolved NH4Cl, and a little H2O is added, shifting the color from blue to pink again. The reaction can be repeated multiple times.
When the concentration of any of the species in an equilibrium system is changed, the equilibrium is disturbed and the system will react so as to minimize the effect of the disturbance.