1. Ch. 16 Solutions Ch. 16.1 Properties of Solutions

2. Solution Formation The composition of the solvent and the solute determine whether a substance will dissolve. The composition of the solvent and the solute determine whether a substance will dissolve. The speed of dissolving depends on stirring (agitation), temperature, and surface area of the dissolving particles. The speed of dissolving depends on stirring (agitation), temperature, and surface area of the dissolving particles. Stirring or shaking increases rate of solvation by continually bringing fresh solvent into contact with the surface of the solute. Stirring or shaking increases rate of solvation by continually bringing fresh solvent into contact with the surface of the solute.

3. Higher temperature of solvent means higher avg. kinetic energy of solvent particles; increased frequency and force of collisions between solvent particles and solute surfaces. So faster dissolving. Higher temperature of solvent means higher avg. kinetic energy of solvent particles; increased frequency and force of collisions between solvent particles and solute surfaces. So faster dissolving. Smaller particle sizes dissolve faster, due to an increased surface area to volume ratio. Smaller particle sizes dissolve faster, due to an increased surface area to volume ratio.

4. Solubility Only a certain maximum amount of salt will dissolve in a given volume of water at a given temperature. Only a certain maximum amount of salt will dissolve in a given volume of water at a given temperature. An equilibrium is reached in which the number of particles leaving the solid and going into solution equals the number of particles leaving the solution and recrystalizing on the solid. An equilibrium is reached in which the number of particles leaving the solid and going into solution equals the number of particles leaving the solution and recrystalizing on the solid.

5. Saturated Solution—contains the maximum amount of solute for a given quantity of solvent at a constant temp. and pressure. Saturated Solution—contains the maximum amount of solute for a given quantity of solvent at a constant temp. and pressure. Solubility—the amount of solute that dissolves in a given quantity of solvent at a specified temp. and pressure to produce a saturated solution. Usually grams of solute per 100 g of solvent. Solubility—the amount of solute that dissolves in a given quantity of solvent at a specified temp. and pressure to produce a saturated solution. Usually grams of solute per 100 g of solvent.

6. Unsaturated solution—a solution that contains less solute than a saturated solution at a given temp. and pressure. Unsaturated solution—a solution that contains less solute than a saturated solution at a given temp. and pressure. Some liquids are infinitely soluble in each other…they are miscible if they dissolve in all proportions. Some liquids are infinitely soluble in each other…they are miscible if they dissolve in all proportions. Liquids insoluble in each other are immicible. Liquids insoluble in each other are immicible.

7. Factors Affecting Solubility Temperature—the solubility of most solid substances increases as temp. increases. Temperature—the solubility of most solid substances increases as temp. increases. Supersaturated solution—contains more solute than it can theoretically hold at a given temperature. Unstable. Supersaturated solution—contains more solute than it can theoretically hold at a given temperature. Unstable. Gases are more soluble in cold solvents than in hot. Pressure also affects the solubility of gases. Gases are more soluble in cold solvents than in hot. Pressure also affects the solubility of gases.

8. Pressure Pressure changes strongly affect the solubility of gases (unlike solids and liquids). Gas solubility increases as the partial pressure of the gas above the solution increases. Pressure changes strongly affect the solubility of gases (unlike solids and liquids). Gas solubility increases as the partial pressure of the gas above the solution increases. Henry’s Law relates the solubility of a gas to its partial pressure. Henry’s Law relates the solubility of a gas to its partial pressure. S 1 /P 1 = S 2 /P 2 S 1 /P 1 = S 2 /P 2