Determine The Equilibrium Constant for Colored Species

• Classic AP Chemistry Experiment
• Instructions Included

The idea of the reversibility of chemical reactions was first stated by C. Berthollet in 1799. He noted deposits of sodium carbonate in certain salt lakes in Egypt and concluded that they were produced by the high concentration of sodium chloride and dissolved calcium carbonate. This is the reverse of the standard laboratory procedure in which calcium carbonate is produced from the reaction on sodium carbonate and calcium chloride. A standard curve will be established for the absorbance of a colored species and then used to determine the concentrations of unknown solutions. The results will allow us to determine the equilibrium constant for the formation of the colored species.