2 A phase is a homogeneous part of the system in contact with other parts of the system but separated from them by a well-defined boundary.2 PhasesSolid phase - iceLiquid phase - water
3 Intermolecular Forces Intermolecular forces are attractive forces between molecules.Intramolecular forces hold atoms together in a molecule.Intermolecular vs Intramolecular41 kJ to vaporize 1 mole of water (inter)930 kJ to break all O-H bonds in 1 mole of water (intra)“Measure” of intermolecular forceboiling pointmelting pointDHvapDHfusDHsubGenerally, intermolecular forces are much weaker than intramolecular forces.
4 Intermolecular Forces Dipole-Dipole ForcesAttractive forces between polar moleculesOrientation of Polar Molecules in a Solid
5 Intermolecular Forces Ion-Dipole ForcesAttractive forces between an ion and a polar moleculeIon-Dipole Interaction
6 Interaction Between Water and Cations in solution
7 Intermolecular Forces Dispersion ForcesAttractive forces that arise as a result of temporary dipoles induced in atoms or moleculesion-induced dipole interactiondipole-induced dipole interaction
9 Intermolecular Forces Hydrogen BondThe hydrogen bond is a special dipole-dipole interaction between the hydrogen atom in a polar N-H, O-H, or F-H bond and an electronegative O, N, or F atom.AH…BorA & B are N, O, or F
10 11.2 Which of the following can form hydrogen bonds with water? CH3OCH3CH4F2HCOOHNa+
12 11.1What type(s) of intermolecular forces exist between the following pairs?HBr and H2SCl2 and CBr4I2 andNH3 and C6H6
13 *Like different TV channel packages Total attractionpremiumHydrogen bondDipole-dipoleDispersion*Like different TV channel packagesbasic
14 van der Waals forcesDipole-dipoleDipole-induced dipoleDispersion
15 Intermolecular Forces Dispersion Forces ContinuedPolarizability is the ease with which the electron distribution in the atom or molecule can be distorted.Polarizability increases with:greater number of electronsmore diffuse electron cloudDispersion forces usually increase with molar mass.
16 Differences in Melting and Boiling point Melting and boiling points increase as the number of electrons in a molecule increasesMore electrons = larger molar mass
17 Why is the hydrogen bond considered a “special” dipole-dipole interaction? Decreasing molar massDecreasing boiling point
18 Strong intermolecular forces Properties of LiquidsSurface tension is the amount of energy required to stretch or increase the surface of a liquid by a unit area.Strong intermolecular forcesHigh surface tension
19 Properties of LiquidsCohesion is the intermolecular attraction between like moleculesAdhesion is an attraction between unlike moleculesAdhesionCohesion
20 Strong intermolecular forces Properties of LiquidsViscosity is a measure of a fluid’s resistance to flow.Strong intermolecular forcesHigh viscosity
21 Ice is less dense than water 3-D Structure of WaterWater is a Unique SubstanceMaximum Density40CDensity of WaterIce is less dense than water
22 A crystalline solid possesses rigid and long-range order A crystalline solid possesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy specific (predictable) positions.An amorphous solid does not possess a well-defined arrangement and long-range molecular order.Crystallinequartz (SiO2)Non-crystallinequartz glassA glass is an optically transparent fusion product of inorganic materials that has cooled to a rigid state without crystallizing
23 An Arrangement for Obtaining the X-ray Diffraction Pattern of a Crystal.
24 Reflection of X-rays from Two Layers of Atoms Extra distance =BC + CD =2d sinq= nl(Bragg Equation)
25 Types of Crystals Ionic Crystals Lattice points occupied by cations and anionsHeld together by electrostatic attractionHard, brittle, high melting pointPoor conductor of heat and electricityCsClZnSCaF2
26 Types of Crystals Covalent Crystals Lattice points occupied by atoms Held together by covalent bondsHard, high melting pointPoor conductor of heat and electricitycarbonatomsdiamondgraphite
27 Types of Crystals Molecular Crystals Lattice points occupied by moleculesHeld together by intermolecular forcesSoft, low melting pointPoor conductor of heat and electricitywaterbenzene
28 Cross Section of a Metallic Crystal Types of CrystalsMetallic CrystalsLattice points occupied by metal atomsHeld together by metallic bondsSoft to hard, low to high melting pointGood conductors of heat and electricityCross Section of a Metallic Crystalnucleus &inner shell e-mobile “sea”of e-
31 Effect of Temperature on Kinetic Energy T2 > T1
32 The equilibrium vapor pressure is the vapor pressure measured when a dynamic equilibrium exists between condensation and evaporationH2O (l) H2O (g)Rate ofcondensationevaporation=Dynamic Equilibrium
33 Measurement of Vapor Pressure BeforeEvaporationAt Equilibrium
34 Vapor Pressure Versus Temperature Molar heat of vaporization (DHvap) is the energy required to vaporize 1 mole of a liquid at its boiling point.ln P = -DHvapRT+ CClausius-Clapeyron EquationP = (equilibrium) vapor pressureT = temperature (K)R = gas constant (8.314 J/K•mol)Vapor Pressure Versus Temperature
35 Alternate Forms of the Clausius-Clapeyron Equation At two temperaturesor
36 11.7Diethyl ether is a volatile, highly flammable organic liquid that is used mainly as a solvent.The vapor pressure of diethyl ether is 401 mmHg at 18°C. Calculate its vapor pressure at 32°C.
37 The boiling point is the temperature at which the (equilibrium) vapor pressure of a liquid is equal to the external pressure.The normal boiling point is the temperature at which a liquid boils when the external pressure is 1 atm.
38 The critical temperature (Tc) is the temperature above which the gas cannot be made to liquefy, no matter how great the applied pressure.The critical pressure (Pc) is the minimum pressure that must be applied to bring about liquefaction at the critical temperature.
39 The Critical Phenomenon of SF6 T < TcT > TcT ~ TcT < Tc
40 Solid-Liquid Equilibrium H2O (s) H2O (l)The melting point of a solid or the freezing point of a liquid is the temperature at which the solid and liquid phases coexist in equilibrium.
41 Molar heat of fusion (DHfus) is the energy required to melt 1 mole of a solid substance at its freezing point.
43 Solid-Gas Equilibrium H2O (s) H2O (g)Molar heat of sublimation (DHsub) is the energy required to sublime 1 mole of a solid.DHsub = DHfus + DHvap( Hess’s Law)
44 11.8Calculate the amount of energy (in kilojoules) needed to heat 346 g of liquid water from 0°C to 182°C.Assume that the specific heat of water is J/g · °C over the entire liquid range and that the specific heat of steam is 1.99 J/g · °C.
45 A phase diagram summarizes the conditions at which a substance exists as a solid, liquid, or gas. Phase Diagram of Water
46 Phase Diagram of Carbon Dioxide At 1 atmCO2 (s) CO2 (g)
47 Effect of Increase in Pressure on the Melting Point of Ice and the Boiling Point of Water