Terms • Solute• Substance that has been dissolved in a liquid

• Solvent• the solution (liquid or gas) part of the solute concentration• Dissolves the solute

• Solubility • The ability of a substance (solute) to dissolve

• Soluble – substance will completely dissolve • Partially Soluble – substance will dissolve but there will be some

precipitate left• Insoluble – will dissolve but the amount that dissolves is very small

and almost ALL the substance precipitates.

Solubility • When the solid is first put into the water, the rate of dissolving

is high. • There is lots of room in the solution for ions• Rate of forward reaction is high• Dissolving

• After time some of these free ions will collide and go back towards the solid • Rate of reverse reaction increases • This process is called precipitation

Solubility • Solubility Equilibrium exists when• The rate of dissolving = The rate of precipitation• Forward Reaction = Reverse Reaction • Only look at partially soluble and insoluble solids

• Ksp• Equilibrium constant for an ionic substance dissolving in water• Solubility product constant

• Molar solubility• Ability of a substance (solute) to dissolve in a substance (solvent)• # of moles that dissolve in 1 L

Solubility• Keq = [products] [reactants]• Ksp = [products]• We don’t take out the solids because their concentrations are

constant

• Example• PbCl2(s) Pb2+(aq) + 2Cl (aq)‐

Keq = [Pb2] [Cl]2

PbCl2

Ksp = [Pb2] [Cl]2

Ionic Charges