Common Ion Effect
Solubility product
The Solubility product is related to SPARINGLY SOLUBLE SALTS ONLY!!!!! Examples are silver chloride, lead(II) chloride, calcium sulphate (in other words, it deals with salts commonly called insoluble salts)
Consider a sparingly soluble salt MX
Imagine the reaction that occurs when the solid is placed in water
aMX (s) + H2O [pic] aMn+ (aq) + bXm- (aq)
The equilibrium expression would be [Mn+]a [Xm-]b [MX]a [H2O]
However the concentrations of both the solid AND the water are constants, so a new equilibrium expression called Ksp is derived
Ksp = [Mn+]a [Xm-]b
Note: The product of the concentration of ions of a sparingly soluble salt in water OTHER than at equilibrium is called the IONIC PRODUCT
Example 1. AgCl [pic] Ag+ + Cl- Ksp = [Ag+][Cl-]
Example 2 Cu(OH)2 [pic] Cu2+ + 2OH- Ksp = [Cu2+][OH-]2
Checkpoint A
Write the Ksp expressions for the sparingly soluble salts below
a. AgF b. HgCl2 c. Cu(OH)2
Common ion effect
The solubility of one salt is reduced by the presence of another salt having a common ion.
For example consider the reaction AgCl (s) [pic] Ag+ (aq) + Cl- (aq)
The ions present in solution are Ag+ and Cl- from the salt silver chloride.
Imagine a soluble salt such as ammonium chloride is added to the solution, with reference to Le Chatelier’s Principle, what would happen??
The addition of more chloride ions would increase the [Cl-] in the equilibrium shown above and the system would then try to decrease the [Cl-] by shifting the equilibrium to the LEFT.
By shifting to the left, this causes an increase in the amount of solid silver chloride formed, i.e. the solubility of the silver chloride decreases in the presence of ammonium chloride. What would be observed is an increased amount of precipitation when the salt ammonium chloride (or any salt
The Solubility product is related to SPARINGLY SOLUBLE SALTS ONLY!!!!! Examples are silver chloride, lead(II) chloride, calcium sulphate (in other words, it deals with salts commonly called insoluble salts)
Consider a sparingly soluble salt MX
Imagine the reaction that occurs when the solid is placed in water
aMX (s) + H2O [pic] aMn+ (aq) + bXm- (aq)
The equilibrium expression would be [Mn+]a [Xm-]b [MX]a [H2O]
However the concentrations of both the solid AND the water are constants, so a new equilibrium expression called Ksp is derived
Ksp = [Mn+]a [Xm-]b
Note: The product of the concentration of ions of a sparingly soluble salt in water OTHER than at equilibrium is called the IONIC PRODUCT
Example 1. AgCl [pic] Ag+ + Cl- Ksp = [Ag+][Cl-]
Example 2 Cu(OH)2 [pic] Cu2+ + 2OH- Ksp = [Cu2+][OH-]2
Checkpoint A
Write the Ksp expressions for the sparingly soluble salts below
a. AgF b. HgCl2 c. Cu(OH)2
Common ion effect
The solubility of one salt is reduced by the presence of another salt having a common ion.
For example consider the reaction AgCl (s) [pic] Ag+ (aq) + Cl- (aq)
The ions present in solution are Ag+ and Cl- from the salt silver chloride.
Imagine a soluble salt such as ammonium chloride is added to the solution, with reference to Le Chatelier’s Principle, what would happen??
The addition of more chloride ions would increase the [Cl-] in the equilibrium shown above and the system would then try to decrease the [Cl-] by shifting the equilibrium to the LEFT.
By shifting to the left, this causes an increase in the amount of solid silver chloride formed, i.e. the solubility of the silver chloride decreases in the presence of ammonium chloride. What would be observed is an increased amount of precipitation when the salt ammonium chloride (or any salt