Chapter 12: SolutionsSolutionsSolutions and SolvationMany Different Types of SolutionsNature’s Tendency Toward Mixing: EntropySolutions and Intermolecular ForcesIntermolecular ForcesExampleEnergetics of Solution FormationPowerPoint Presentation“Like Dissolves Like”Practice—Decide if the following are more soluble in hexane, C6H14,or water.Solution EquilibriumTemperature and solubility of solidsSolubility of GasesChapter 12 1Chapter 12: SolutionsGeorgia Gwinnett CollegeChem 1212KSpring 2011(B. Shepler)Solutions•Mixture: Different types of atoms or molecules. Not definite porportions.•Heterogeneous: Observable boundaries between components. Often represened by different phases (but not always). Not uniform•Homogenous: No observable boundaries. Uniform. Solutions (not just liquid)–SolubilityChapter 12 23Solutions and Solvation•Solution: A homogenous mixture of two or more substances that has no visible boundaries among its components. The substances disperse into each other at the level of individual atoms/molecules/ions.•Two major components of a solution:–Solvent: The substance present in the greater amount.–Solute: The substance present in the lesser amount.•We say the solute dissolves in the solvent•Solvation (also dissolution): The process of surrounding solute particles with solvent particles.4Many Different Types of Solutions•The solute and solvent can each be any combination of solid/liquid/gas.•Examples:Solute Solvent ExampleGas Gas Air in this roomLiquid Liquid Ethanol and Water in alcoholic bev. water and antifreezeGas Liquid CO2 in sodaGas SolidH2 in metals hydrogen storageSolid Liquid sugar in iced teaNature’s Tendency Toward Mixing: Entropy•Entropy: A measure of energy randomization or energy dispersal.–In nature energy tends to spread out when it is not restrained from doing so.–Related to disorder on the molecular level.•Clean room will tend to get messy unless you expend energy to clean it.Chapter 12 5Solutions and Intermolecular Forces•Intermolecular forces may promote or prevent the formation of a solution.•Intermolecular forces exist between all of the components of the solution.Chapter 12 6Intermolecular ForcesChapter 12 7Example•What would be the solute-solute, solvent-solvent, and solute-solvent intermolecular forces in the following solutions.–Solute: NaCl Solvent: Water–Solute: Methane Solvent: Benzene (C6H6)–Solute: Ethanol Solvent: Water–Solute: Methane Solvent: WaterChapter 12 8Energetics of Solution FormationChapter 12 9Chapter 12 10“Like Dissolves Like”•For a solution to form we must break the solute-solute and solvent-solvent interactions. We make new solvent-solute interactions.•Solutes tend to dissolve in solvents that have similar intermolcular forces.Chapter 12 1112Practice—Decide if the following are more soluble in hexane, C6H14,or water.naphthaleneformaldehydestearic acidSolution Equilibrium•Solubility: the amount of solute we can dissolve in a given amount of solute.•Saturated Solution: A solution in which the dissolved solute is in dynamic equilibrium with undissolved solute. The maximum amount of solute has been disolved.13Temperature and solubility of solidsChapter 12 14Solubility of Gases•Temperature: Gas solubility decreases with increasing temperature. More KE means the gases want to escape the solution.•Pressure: Gas solubility increases with pressure. In effect the higher pressure effectively forces the gases into solution.Chapter 12