Answer to Question #137894 in Organic Chemistry for Edward Calamigan

Question

Several ammount of unknown salt was added to a solvent. Initial amount of solvnet is 30 ml. When the mixture weighed 0.2202 lb, undissolved salts were observed. Upon seperation of the salts, it was found to be around 5 g. What is the solubility of the unknown salt? Before seperating the undissolved solute from the mixture, was the solution supersaturated and why? (Density of the solvent=1.02 g/mL)

Answer 1

A solution of a chemical compound in a liquid will become supersaturated when the temperature of the saturated solution is changed. In most cases solubility decreases with decreasing temperature; in such cases the excess of solute will rapidly separate from the solution as crystals or an amorphous powder.

Supersaturation occurs with a chemical solution when the concentration of a solute exceeds the concentration specified by the value equilibrium solubility. Most commonly the term is applied to a solution of a solid in a liquid. A supersaturated solution is in a metastable state; it may be brought to equilibrium by forcing the excess of solute to separate from the solution. The term can also be applied to a mixture of gases.