SOLUBILITY AND SIMULTANEOUS EQUILIBRIA
A. solubility product constant, K(sp)
1. equilibrium constant when the system is a solubility equilibrium and the constant equals a product of ion concentrations
a. System is a heterogeneous equilibrium
2. Ion Products -- product of the molar concentrations of the dissolved ions of the solute
a. only called "solubility product constant" when it is a saturated solution
b. when unsaturated, ion product < K(sp)
c. when supersaturated, ion product > K(sp)
B. Using Molar Solubility to Determine K(sp)
1. Molar solubility --> the number of moles of salt dissolved in one liter of its saturated solution
2. When the asumption of 100% dissociation is valid, the K(sp) value for any 1:1 salt in water having no other solute will always be the square of the molar solubility
a. when it is not 1:1, then you must "ICE" the problem
b. when the aqueous system already contains solute, then you must "ICE" the problem
C. Calculating Molar solubility from K(sp)
1. Opposite of above procedure (ICE)
D. Common Ion Efect
1. Common Ion --> an ion in solution that has been supplied from more than one solute
2. Common Ion Effect --> the lowering of the solubility of an ionic compound by the addition of a common ion
3. A Common mistake when "ICE"ing these problems
a. When a second salt is added with a coefficient other than 1, the coefficient is only used on the Change line, not the Initial line
E. Determining if a Precipitate wil form in a Solution
1. Compare ion products with K(sp)
2. Precipitate will form -- Ion product > K(sp) (supersaturated)
3. Precipitate will not form -- Ion product = k(sp) (saturated)
4. Precipitate will not form -- Ion product < K(sp) (unsaturated)
Outline based upon:
Brady, J. E., Holum, J. R., Russell, J. W. (2000). Chemistry: The Study of Matter and Its Changes. (3rd ed.). New York: John Wiley & Sons, Inc. pp. 759-784.
