Ch. 16 SolutionsCh. 16 SolutionsCh. 16.1 Properties of Ch. 16.1 Properties of

SolutionsSolutions

Solution FormationSolution Formation• The composition of the solvent and the The composition of the solvent and the

solute determine whether a substance will solute determine whether a substance will dissolve.dissolve.

• The speed of dissolving depends on stirring The speed of dissolving depends on stirring (agitation), temperature, and surface area of (agitation), temperature, and surface area of the dissolving particles.the dissolving particles.

• Stirring or shaking increases rate of solvation Stirring or shaking increases rate of solvation by continually bringing fresh solvent into by continually bringing fresh solvent into contact with the surface of the solute.contact with the surface of the solute.

• Higher temperature of solvent means Higher temperature of solvent means higher avg. kinetic energy of solvent higher avg. kinetic energy of solvent particles; increased frequency and force particles; increased frequency and force of collisions between solvent particles of collisions between solvent particles and solute surfaces. So faster dissolving.and solute surfaces. So faster dissolving.

• Smaller particle sizes dissolve faster, due Smaller particle sizes dissolve faster, due to an increased surface area to volume to an increased surface area to volume ratio.ratio.

SolubilitySolubility• Only a certain maximum amount of Only a certain maximum amount of

salt will dissolve in a given volume of salt will dissolve in a given volume of water at a given temperature.water at a given temperature.

• An equilibrium is reached in which the An equilibrium is reached in which the number of particles leaving the solid number of particles leaving the solid and going into solution equals the and going into solution equals the number of particles leaving the number of particles leaving the solution and recrystalizing on the solid.solution and recrystalizing on the solid.

• Saturated SolutionSaturated Solution—contains the —contains the maximum amount of solute for a given maximum amount of solute for a given quantity of solvent at a constant temp. quantity of solvent at a constant temp. and pressure.and pressure.

• SolubilitySolubility—the amount of solute that —the amount of solute that dissolves in a given quantity of solvent at dissolves in a given quantity of solvent at a specified temp. and pressure to produce a specified temp. and pressure to produce a saturated solution. Usually a saturated solution. Usually grams of grams of solute per 100 g of solvent.solute per 100 g of solvent.

• Unsaturated solutionUnsaturated solution—a solution that —a solution that contains less solute than a saturated contains less solute than a saturated solution at a given temp. and pressure.solution at a given temp. and pressure.

• Some liquids are infinitely soluble in Some liquids are infinitely soluble in each other…they are each other…they are miscible miscible if they if they dissolve in all proportions.dissolve in all proportions.

• Liquids insoluble in each other are Liquids insoluble in each other are immicibleimmicible..

Factors Affecting SolubilityFactors Affecting Solubility• Temperature—the solubility of most Temperature—the solubility of most

solid substances increases as temp. solid substances increases as temp. increases.increases.

• Supersaturated solution—contains Supersaturated solution—contains more solute than it can theoretically more solute than it can theoretically hold at a given temperature. Unstable.hold at a given temperature. Unstable.

• Gases are more soluble in cold solvents Gases are more soluble in cold solvents than in hot . Pressure also affects the than in hot . Pressure also affects the solubility of gases.solubility of gases.

PressurePressure• Pressure changes strongly affect the Pressure changes strongly affect the

solubility of gases (unlike solids and solubility of gases (unlike solids and liquids). Gas solubility increases as liquids). Gas solubility increases as the partial pressure of the gas above the partial pressure of the gas above the solution increases.the solution increases.

• Henry’s Law relates the solubility of a Henry’s Law relates the solubility of a gas to its partial pressure.gas to its partial pressure.

• SS11/P/P11 = S = S22/P/P22