Chapter 13.2 : The Solution Process
- 1. The solution processChapter 13.2Objectives :List and explain three factors that affect the rate at which a solid solute dissolves in a liquid solvent.Explain solution equilibrium, and distinguish among saturated, unsaturated, and supersaturated solutions.Explain the meaning of “like dissolves like” in terms of polar and nonpolar substances.List the three interactions that contribute to the heat of solution, and explain what causes dissolution to be exothermic or endothermic.Compare the effects of temperature and pressure on solubility.
- 2. Factors Affecting the Rate of DissolutionIncreasing the surface area of the soluteSugar cube will dissolve slower than ground up sugarAgitating a solutionStir your iced tea and the sugar will dissolve faster.Heating a SolventSugar dissolves faster in hot tea
- 3. SolubilitySolution equilibriumPhysical state in which the opposing processes of dissolution and crystallization of a solute occur at equal rates.Saturated solutionSolution that contains the maximum amount of dissolved soluteExample: At 20oC, 35.9 g of NaCl is the maximum amount that will dissolve in 100. g of waterUnsaturated solutionSolution that contains less solute than a saturated solution under existing conditions
- 4. Supersaturated solutionsSolution that contains more dissolved solute than a saturated solution contains under the same conditions.Disturbing solution will cause rapid crystallizationVideo demonstration 1Video demonstration 2Solvent : waterSolute : glucose
- 5. Solute-Solvent Interactions“Like dissolves Like”Polar will dissolve polarNonpolar will dissolve nonpolarPolar will NOT dissolve in nonpolarDissolving ionic compounds in aqueous solutionsHydration : solution process with water as the solventCuSO4•5H2O - hydrateCrystalline compounds that incorporate water molecules
- 6. Nonpolar solventsCarbon tetrachloride and tolueneSubstances similar to oilLiquid solutes and solventsImmiscibleLIQUID solutes and solvents that are not soluble in each otherExample: oil and vinegarMiscibleLiquids that dissolve freely in one another in any proportionsEthanol and water
- 7. Effects of Pressure on SolubilityIncrease in pressure – increases gas solubilities in liquidsgas + solvent solutionHenry’s LawSolubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid.EffervescenceRapid escape of a gas from a liquid in which it is dissolvedMentos demo
- 8. Effects of Temperature on SolubilityFor gaseoussolutesIncrease in temperatureDecrease in solubilityFor solid solutesIncrease in temperatureIncrease in solubility
- 9. Heats of solutionFormation of solution – accompanied by energy changeDissolving KIFeels cold Dissolving LiClFeels hotExamples of graphing different heats of solutionsSolvated : A solute particle that is surrounded by solvent moleculesHeat of Solution – net amount of heat energy absorbed or released when a specific amount of solute dissolves