Ch 16

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Tsum Tsum

Cards (11)

Solubility Equilibria
Solubility product constant (Ksp)
Equilibrium constant expression that represents the dissolution of an ionic solid in water
Known as solubility product
Solubility equilibrium is unaffected by:
Excess solid formed
Size of particles present
Differences between the solubility of a given solid and its solubility product
Solubility is an equilibrium position
Solubility product is an equilibrium constant
Has only onevalue for a given solid at a given temperature
Common Ion Effect
The solubility of a solid becomes low when the solution already contains ions common to the solid
Increase in pH = decrease in solubility
Forces the equilibrium to the left
Decrease in pH
Increases solubility
Equilibrium shifts to the right
pH and Solubility (Continued)
Exception -AgCl has the same solubility in acid as in pure water
Cl–ion is a weak base
No HCl molecules are formed
Adding H+ions to a solution that contains Cl–ions does not affect:
Concentration of the Cl–ion
Solubility of the chloride salt
Ion product (Q)
Defined similar to the expression for Kspfor a given solid
Exception -Initial concentrations are used instead of equilibrium concentrations
Q > Ksp
Precipitation will occur
Q < Ksp
No precipitation
Selective Precipitation
Method used to separate mixtures of metal ions in aqueous solution
Involves using a reagent whose anion forms a precipitate with only one or a few of the metal ions in the mixture
Selective precipitation is a technique of separating ions in an aqueous solution by using a reagent that precipitates one or more of the ions, while leaving other ions in solution. Qualitative Analysis for Metallic Elements.
Involves separating common cations into five major groups based on solubilities
Individual ions are then identified from each of the groups
Group I -Insoluble chlorides
Group II -Sulfides insoluble in acid solution
Group III -Sulfides insoluble in basic solution
Group IV-Insoluble carbonates
Group V -Alkali metal and ammonium ions