12Normality Calculations .250 M H3PO4 =______NN = M(total(+) charge)N = (0.250)(3)N = N H3PO4
13Concentration & Density Calculations See Example 11.2 on pagesKnow how to do this problem!!
14Steps in Solution Formation Step 1 - Expanding the solute (endothermic)Step 2 - Expanding the solvent (endothermic)Step 3 - Allowing the solute and solvent to interact to form a solution (exothermic)Hsoln = Hstep 1 + Hstep 2 + Hstep 3
15Three steps of a liquid solution: 1) expanding the solute, 2) expanding the solvent, & 3) combining the expandedsolute and solvent to form the solution.
16a) Hsoln is negative and solution process is exothermic. b) Hsoln is positve and solution process is endothermic.
17Processes that require large amounts of energy tend not to occur. Solution process are favored by an increase in entropy.
18Structure & Solubility Like dissolves like.Hydrophobic --water-fearing. Fat soluble vitamins such as A, D, E, & K.Hydrophilic --water-loving. Water soluble vitamins such as B & C.Hypervitaminosis--excessive buildup of vitamins A, D, E, & K in the body.
19Henry’s LawThe amount of a gas dissolved in a solution is directly proportional to the pressure of the gas above the solution.P = kCP = partial pressure of gaseous solute above the solutionC = concentration of dissolved gask = a constant
20Solubility of several solids as a function of temperature.
21The solubility of various gases at different temperatures.
22When an aqueous solution and pure water are in a closed environment, the water is transferred to the solutionbecause of the difference in vapor pressure.
23Psoln = solventPsolvent Raoult’s LawThe presence of a nonvolatile solute lowers the vapor pressure of a solvent.Psoln = solventPsolventPsoln = vapor pressure of the solutionsolvent = mole fraction of the solventPsolvent = vapor pressure of the pure solvent
24Raoult’s Law Calculations Sample Exercise 11.6 on page 532.Na2SO4 forms 3 ions so the number of moles of solute is multiplied by three.Psoln = waterPwaterPsoln = (0.929)(23.76 torr)Psoln = 22.1 torr
25Vapor pressure for a solution of two volatile liquids. a) Ideal(benzene & toluene) -- obeys Raoult’s Law,b) Positive deviation (ethanol & hexane) from Raoult’sLaw, & c) Negative deviation (acetone & water).Negative deviation is due to hydrogen bonding.
26Liquid-Liquid Solutions Ptotal = PA + PB= APoA + BPoB
28Colligative Properties Depend only on the number, not on the identity, of the solute particles in an ideal solution.Boiling point elevationFreezing point depressionOsmotic pressure
29Phase diagrams for pure water and for an aqueous solution containing a nonvolatile solute -- liquid rangeis extended for the solution.
30Boiling Point Elevation A nonvolatile solute elevates the boiling point of the solvent. The solute lowers the vapor pressure of the solution.T = KbmsoluteiKb = molal boiling point elevation constantm = molality of the solutei = van’t Hoff factor ( # ions formed)
34Boiling Point Calculations (Continued) n = m/MM = m/nM = g/0.10 molM = 180 g/mol
35Freezing Point Depression A nonvolatile solute depresses the freezing point of the solvent. The solute interferes with crystal formation.T = KfmsoluteiKf = molal freezing point depression constantm = molality of the solutei = van’t Hoff factor ( # ions formed)
36Freezing Point Calculations Sample Exercise on page 539.T = Kfmsoluteimsolute = T/(Kfi)msolute = (0.240 Co)/[(5.12 Cokg/mol)(1)]msolute = 4.69 x 10-2 mol/kg
37Freezing Point Calculations (Continued) msolute = nsolute/ kgsolventnsolute = msolute kgsolventnsolute = (4.69 x 10-2 mol/kg)( kg)nsolute = 7.04 x mol
38Freezing Point Calculations (Continued) n = m/MM = m/nM = .546 g/7.04 x 10-4 molM = 776 g/mol
39Osmotic PressureOsmosis: The flow of solvent into the solution through the semipermeable membrane.Osmotic Pressure: The excess hydrostatic pressure on the solution compared to the pure solvent.
40Due to osmotic pressure, the solution is diluted bywater transferred throughthe semipermeablemembrane. The dilutedsolution travels up thethistle tube until the osmotic pressure is balanced by thegravitational pull.
41OsmosisThe solute particles interfere with the passage of the solvent, so the rate of transfer is slower from the solution to the solvent than in the reverse direction.
42a) The pure solvent travels at a greater rate into the solution than solvent molecules can travel in the reverse direction.b) At equilibrium, the rate of travel of solvent molecules in bothdirections is equal.
43Osmotic Pressure = MRT = osmotic pressure (atm) M = Molarity of solutionR = Latm/molKT = Kelvin temperature
45Osmotic Pressure Calculations Continued Molar Mass = (1.00 x 10 -3g/1.00 mL)(1000 mL/1 L)(1 L/6.01 x 10-5 mol) =1.66 x 104 g/mol protein
46Crenation & LysisCrenation-solution in which cell is bathed is hypertonic (more concentrated)-cell shrinks. Pickle, hands after swimming in ocean. Meat is salted to kill bacteria and fruits are placed in sugar solution.Lysis-solution in which cell is bathed is hypotonic (less concentrated)-cell expands. Intravenous solution that is hypotonic to the body instead of isotonic.
47If the external pressure is larger than the osmotic pressure, reverse osmosis occurs. One application is desalination of seawater.
48Colligative Properties of Electrolyte Solutions van’t Hoff factor, “i”, relates to the number of ions per formula unit.NaCl = 2, K2SO4 = 3T = mKi = MRTi
49Electrolyte Solutions The value of i is never quite what is expected due to ion-pairing. Some ions stay linked together--this phenomenon is most noticeable in concentrated solutions.
51aerosols, foams, emulsions, sols ColloidsColloidal Dispersion (colloid): A suspension of tiny particles in some medium.aerosols, foams, emulsions, solsCoagulation: The addition of an electrolyte, causing destruction of a colloid. Examples are electrostatic precipitators and river deltas.
52The eight types of colloids and examples of each.
53Tyndall EffectThe scattering of light by particles of a colloid is called the Tyndall Effect. Which of the glasses below contains a colloid?
54Calorimeter ProblemAdd this problem to the Chapter 11 set of problems. KNOW how to work this problem--show the appropriate formula!!When 8.50 g of sodium nitrate is dissolved in g of water, the temperature of the solution rises Co. What is the molar heat of solution for sodium nitrate?