Lecture 1 Notes—Ch.13, Pt.1— Focus of Chapter - Energy change with solution formation - Concentration Units - Colligative Properties Term Review - Solution: Homogeneous mixture. - Solute: Component dissolved in solvent. o Usually present in smaller amount than solvent. - Solvent: Medium into which solutes are mixed. o Usually present in larger amount than solute. o Usually liquid. - Solubility: Measure of how much solvent could go into a given amount of solvent. Molecular View of Solution Process - Intermolecular forces responsible for process. o Disruption of solute-solute interaction. o Disruption of solvent-solvent interaction. o Formation of solute-solvent interaction. — Exothermic ΔH1 = Disrupt solute-solute - ΔH > 0 ΔH2 = Disrupt solvent-solvent - ΔH > 0 ΔH3 = Form solute-solvent - ΔH < 0 ΔHsoln = ΔH1 + ΔH2 + ΔH3 - “Ideal” solution o ΔHsoln = 0 Endothermic- Solutions of gases in liquids o ΔHsoln < 0 (exothermic) o Because solute-solute interactions don’t need to be broken  Low density; particles far from each other; not much interaction  ΔH1 = 0 Solubility Prediction - “Like dissolve like.” - Two nonpolar substances mix o Example) CCl4 dissolves in benzene (C6H6) - Two polar substances mix o Example) H2O and methanol (CH3OH) - Miscible: Two liquids soluble in each other in all proportions. - Immiscible: Two liquids NOT soluble in each other in all proportions. - Ions readily dissolve in polar solvents due to solvation by solvent molecules. o Example) NaCl into H2O Energy and Entropy in Solution Formation - Exothermic processes are generally more favorable than Endothermic processes in nature. o HOWEVER, solutions can still form if ΔHsoln > 0 - All processes are controlled by Enthalpy and Entropy. o Entropy: Tendency to move toward disorder.  Explains solution mixing in random, homogeneous