1. Chapter 12, pp 401-424 Solutions

2. Types of Mixtures Homogeneous mixtures - Solutions Solvent = dissolving medium (like water) Solute = substance dissolved (like sugar) May exist as liquid, gas, or solid (alloys) Heterogeneous mixtures

3. Mixtures Homogeneous - Solutions Heterogeneous –Suspensions: particles settle out –Colloids: dispersion Emulsions – milk, mayonnaise, cheese, butter Foam – shaving cream, whipped cream Gels - gelatin Aerosol – smoke, fog, clouds, mist, exhaust Sol – paints, mud

4. Distinguishing Properties Particle size – 0.01 – 1 nm = solution – 1-1000 nm = colloid – 1000 + nm = suspension Filtration – Suspensions only Tyndall effect (light scattering) – Heterogeneous mixtures only

5. Solute-Solvent Interactions “Like dissolves like.” – Polar or ionic solutes in polar solvents – Nonpolar solutes in nonpolar solvents – Soap has polar AND nonpolar ends Pressure – Increases gas solubility in liquids Henry’s Law – Solubility of gas in liquid directly proportional to partial pressure of that gas above the liquid

6. Solutes Electrolytes –Conducts electricity in aqueous sol’n –Salts (NaCl, HCl, MgBr 2, etc…) Nonelectrolytes –Does NOT conduct electricity –Sugars, nonpolar molecules

7. Solution Process Factors affecting rate of dissolution –Surface area of solute –Kinetic energy (agitation) –Temperature (usually heat is better) –Concentration (amount of solute per solvent) –Polar vs. nonpolar (“Like dissolves like.”) –Pressure (gas in liquids) Henry’s Law

8. Enthalpies of Solution Changes in molecular bonds are required  Solute-solute; solvent-solvent Solvation involves changes in energy –Heat absorbed by solution (endothermic) KI dissolved in water feels cold –Heat released by solution (exothermic) NaOH dissolved in water feels warm

9. Concentrations of Sol’n Molarity –Moles of solute/ Liter of sol’n  “M” Molality –Moles of solute/ Kilogram of solvent  “m” Normality (FYI) –One gram equivalent of solute/ Liter of sol’n  “N”

10. Saturation Saturated = contains max am’t of solute Unsaturated = less than max amount Supersaturated = more than saturated –Heat solvent as solute is added –Leave undisturbed –Crystal formation returns sol’n to equilibrium

11. Saturation Curve Mass (grams) per 100g H 2 O vs. Temperature 20 40 60 0 020406080100  Saturated Supersaturated Unsaturated Temperature, o C Grams per 100g H 2 O

12. Solubility Curve