OFB Chapter 6 Condensed Phases and Phase Transitions

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OFB Chapter 6 Condensed Phases and Phase Transitions. 6-1 Intermolecular Forces: Why Condensed Phases Exist 6-2 The Kinetic Theory of Liquids and Solids 6-3 Phase Equilibrium 6-4 Phase Transitions 6-5 Phase Diagrams 6-6 Colligative Properties of Solutions 6-7 Mixtures and Distillation - PowerPoint PPT Presentation

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<ul><li><p>OFB Chapter 6Condensed Phases andPhase Transitions6-1 Intermolecular Forces: Why Condensed Phases Exist6-2 The Kinetic Theory of Liquids and Solids6-3 Phase Equilibrium6-4 Phase Transitions6-5 Phase Diagrams6-6 Colligative Properties of Solutions6-7 Mixtures and Distillation6-8 Colloidal Dispersions</p><p>OFB Chapter 6</p></li><li><p>Intermolecular Forces: Why Condensed Phases ExistIntramolecular ForcesChemical bondsStrongDirectionalShort Range (relative)Intermolecular ForcesWeaker than chemical bonds, usually much weakerLess directional than covalent bonds, more directional than ionic bondsLonger range than covalent bonds but at shorter range than ionic bondsCondensed PhasesSolids and LiquidsIntermolecular forces: mutual attractions hold the molecules closer together than gasesPotential Energy CurvesDistinction between intramolecular and intermolecular Forces</p><p>OFB Chapter 6</p></li><li><p>Potential Energy At Rest Stretched, then relaxed Compressed, then relaxed</p><p>OFB Chapter 6</p></li><li><p>Potential Energy Curves</p><p>OFB Chapter 6</p></li><li><p>Potential Energy CurvesAtoms or molecules approach at large distance (zero PE (energy of position)PE goes negative as intermolecular forces come into playPE minimum energy well is a balance of Intermolecular forces and repulsive forcesPE goes positive as repulsive forces dominate</p><p>OFB Chapter 6</p></li><li><p>Types of Non-Bonded (Intermolecular) Attractions Dipole-Dipole Interactions e.g., Hydrogen BondingIon-Dipole InteractionsInduced Dipole AttractionsDispersive Forces temporary fluctuations in electron distribution</p><p>OFB Chapter 6</p></li><li><p>Types of Non-Bonded (Intermolecular) Attractions Dipole-Dipole Interactions e.g., Hydrogen Bonding</p><p>OFB Chapter 6</p></li><li><p>Types of Non-Bonded (Intermolecular) Attractions Dipole-Dipole Interactions e.g., Hydrogen BondingIon-Dipole Interactions</p><p>OFB Chapter 6</p></li><li><p>Types of Non-Bonded (Intermolecular) Attractions Dipole-Dipole Interactions e.g., Hydrogen BondingIon-Dipole InteractionsInduced Dipole Attractions</p><p>Argon AtomArgon Atom</p><p>OFB Chapter 6</p></li><li><p>Types of Non-Bonded (Intermolecular) Attractions Dipole-Dipole Interactions e.g., Hydrogen BondingIon-Dipole InteractionsInduced Dipole AttractionsDispersive Forces temporary fluctuations in electron distribution</p><p>OFB Chapter 6</p></li><li><p>Types of Non-Bonded (Intermolecular) Attractions Dipole-Dipole Interactions e.g., Hydrogen BondingBetween H2O to H2O or R-OH to H2O or R-OH to R-OH (R is an organic unit)</p><p>OFB Chapter 6</p></li><li><p>Kinetic Theory of Liquids and Solids</p><p>OFB Chapter 6</p></li><li><p>6-3 Phase EquilibriumCoexisting phase equilibriumVapor pressurePhase: A sample of matter that is uniform throughout, both in its chemical constitution and in its physical state.</p><p>OFB Chapter 6</p></li><li><p>Correcting for the Vapor Pressure of Water in Wet GasesMany chemical reactions conducted in aqueous solution often generate gaseous productsThe gas collected will be humid or wet due to the coexistence of the gas and water vapor.A correction is made to account for the water vapor present </p><p>OFB Chapter 6</p></li><li><p>Exercise page 6-2:Passage of an electric current through a dilute aqueous solution of sodium sulfate produces a mixture of gaseous hydrogen and oxygen according to the following equation:2 H2O(l) 2 H2(g) + O2(g)One liter of the mixed gases is collected over water at 25oC and under a total pressure of 755.3 torr. Calculate the mass of oxygen that is present. The vapor pressure of water is 23.8 torr at 25oC.</p><p>OFB Chapter 6</p></li><li><p>For ideal gas mixturesP of a gas is proportional to the number of moles of gas2 H2O(l) 2 H2(g) + O2(g)Exercise page 6-2:</p><p>OFB Chapter 6</p></li><li><p>OFB Chapter 6</p></li><li><p>6-6 Colligative Properties of SolutionsFor some properties, the amount of difference between a pure solvent and dilute solution depend only on the number of solute particles present and not on their chemical identify.Called Colligative PropertiesExamples1. Vapor Pressure2. Melting Point3. Boiling Point4. Osmotic Pressure</p><p>OFB Chapter 6</p></li><li><p>Colligative Properties of SolutionsMass percentage (weight percentage):mass percentage of the component =Mole fraction:The chemical amount (in moles) divided by the total amount (in moles)X1 = n1/(n1 + n2)X2 = n2/(n1 + n2) = 1 - X1</p><p>OFB Chapter 6</p></li><li><p>Molalitymsolute = moles solute per kilograms solvent = mol kg-1 Molaritycsolute = moles solute per volume solution = mol L-1 </p><p>OFB Chapter 6</p></li><li><p>Exercise 6-7:Suppose that 32.6 g of acetic acid, CH3COOH, is dissolved in 83.8 g of water, giving a total solution volume of 112.1 mL. Calculate the molality and molarity of acetic acid (molar mass 60.05 g mol-1) in this solution.</p><p>OFB Chapter 6</p></li><li><p>Exercise 6-7:Suppose that 32.6 g of acetic acid, CH3COOH, is dissolved in 83.8 g of water, giving a total solution volume of 112.1 mL. Calculate the molality and molarity of acetic acid (molar mass 60.05 g mol-1) in this solution.</p><p>OFB Chapter 6</p></li><li><p>Ideal Solutions and Raoults LawConsider a non-volatile solute in a solventX1 = mole fraction of solventP1=X1 P1Negative deviation= solute-solvent attractions &gt; solvent-solvent attractionsPositive deviation= solute-solvent attractions &lt; solvent-solvent attractions</p><p>OFB Chapter 6</p></li><li><p>Ideal Solutions and Raoults LawLowering of Vapor PressureVapor Pressure of a solvent above a dilute solution is always less than the vapor pressure above the pure solvent.Elevation of Boiling PointThe boiling point of a solution of a non-volatile solute in a volatile solvent always exceeds the boiling point of a pure solvent</p><p>OFB Chapter 6</p></li><li><p>Elevation of Boiling Point Where m = molality (moles of solute per kilogram of solvent)The Effect of Dissociation i = the number of particles released into the solution per formula unit of solutee.g., NaCl dissociates into i = e.g., Na2SO4 dissociates into i = (2 Na+ + 1 SO4-2)</p><p>OFB Chapter 6</p></li><li><p>3. Depression of Freezing PointTf = m KfTf = i m Kf</p><p>OFB Chapter 6</p></li><li><p>Osmotic PressureFourth Colligative PropertyImportant for transport of molecules across cell membranesOsmotic Pressure = = g d h = c RTV = n RTV = i c RT</p><p>OFB Chapter 6</p></li><li><p>Exercise 6-17A dilute aqueous solution of a non-dissociating compound contains 1.19 g of the compound per liter of solution and has an osmotic pressure of 0.0288 atm at a temperature of 37C. Compute the molar mass of the compound</p><p>OFB Chapter 6</p></li><li><p>Exercise 6-17A dilute aqueous solution of a non-dissociating compound contains 1.19 g of the compound per liter of solution and has an osmotic pressure of 0.0288 atm at a temperature of 37C. Compute the molar mass of the compound</p><p>OFB Chapter 6</p></li><li><p>6-8 Colloidal DispersionsColloids are large particles dispersed in solution1nm to 1000 nm in sizeE.g., Globular proteins 500nmExamplesOpal (water in solid SiO2)Aerosols (liquids in Gas)Smoke (solids in Air)Milk (fat droplets &amp; solids in water)Mayonnaise (water droplets in oil)Paint (solid pigments in liquid)Biological fluids (proteins &amp; fats in water)CharacteristicsLarge particle size colloids: translucent, cloudy, milky)Small particle size colloids: can be clear</p><p>OFB Chapter 6</p></li><li><p>6-8 Colloidal DispersionsTyndall Effect Light Scattering</p><p>OFB Chapter 6</p></li><li><p>Chapter 6Condensed Phases and Phase TransitionsExamples / ExercisesAll (6-1 thru 6-17, skip 6-18)HW Problems16, 18, 22, 28, 32, 40</p><p>OFB Chapter 6</p><p>1116</p></li></ul>