CHEM 1442 1st Edition Lecture 5Outline of Last Lecture I. Colligative PropertiesII. Vapor Pressure LoweringOutline of Current Lecture III. ViscosityIV. Surface TensionV. Colligative PropertiesVI. Chapter 16Current LectureViscosityViscosity is the resistance of a liquid to flow. A liquid flows by sliding molecules over one anotherThe higher the viscosity, the stronger the intermolecular forceSurface TensionSurface tension is the amount of energy required to increase the surface area of liquid by a unit amountThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.The higher the surface tension, the stronger the intermolecular forces areExample: Which is greater between H2O AND CH4?a. Intermolecular forcesb. Boiling Pointc. Heat of Vaporizationd. Vapor Pressuree. Freezing Point = Melting Pointf. Surface Tensiong. ViscosityAnswer:a. H2O because it has two hydrogen bondsb. H2O because it is harder to break the bondsc. H2O because it requires more energy to break bondsd. CH4 because it is more volatile and only has dispersion forces so can be easily vaporizede. H2O because it is harder to break the bondsf. H2O because it requires more energyg. H2O because it resists moreColligative PropertiesWhy is density not a colligative property?Because a change in density depends on what type of solute is addedWhat would happen if a small amount of blue ink is dropped in water?DiffusionDiffusion: spontaneous movements of particles from an area of high concentration to a lower concentrationWhen does the “net” diffusion stop?When it hits equilibriumOsmosis: the diffusion of water across a semipermeable membrane, which means only solvent molecules can pass throughWhy does the “net” movement stop?Concentration is still high and not uniformRate of Diffusion () >Rate of Diffusion ()Rate of Diffusion () =Rate of Diffusion ()Now, equilibrium has been met.Osmotic Pressure (Π): pressure of excess fluid stopping the “net” movement (colligative property)Π = MRTM = molarity (mol/L)R = gas constant (0.08206 L x atm/ mol x K)T = absolute temperature (K)Chapter 16Remember to calculate initial rate by using the tangent line at time = 0Rate Law (or Rate Equation or Rate Expression)Goal: To express the rate by using the concentrationsTo express the rate by using the concentrations of reactants.Example:H2SeO3(aq) + 6 I-(aq) + 4 H+(aq) Se(s) + 2 I3-(aq) + 3 H2O(l)Answer: Rate = k [H2SeO3]m [I-]n [H+]pk = rate constant that always has different unitsm, n, p = reaction orders*Do not use x or · to indicate multiplication between the reactants*Example: Rate = k [H2SeO3]m [I-]n [H+]pm = 1, n = 3, and p = 2Answer: Rate = k [H2SeO3] [I-]3 [H+]2H2SeO3is first orderH+is second orderI- is third orderOverall the reaction is sixth order (1+2+3)*In general:Rate order DOES NOT stoichiometric