CHAPTER 13 – LIQUIDS AND SOLIDS1 Kinetic-Molecular Description of Liquids and Solids all ionic compounds are solid at room temperature (have high melting points) all covalent compounds are gases or low-melting-point solids at room temperature liquids and solids are highly incompressible liquids and solids are in condensed states (very high degrees of intermolecular forces) strength of intermolecular forces (strength increases with degree of ordering):solids > liquids >> gasesgases have almost no intermolecular forces! miscible liquids are soluble in each other, while immiscible liquids are not soluble in each other cooling a liquid lowers its molecular kinetic energy, which causes the molecules to slow down2 Intermolecular Attractions and Phase Changes generally speaking:ionic bonding > hydrogen bonding > dipole-dipole bonding >> London forces ion-ion interactions -- governed by Coulomb’s Law: F  (q+)(q-)/d2the higher + and - charges mean higher melting point and boiling point and lower water solubility (this means that +2/-2 is stronger than +1/-1)also, keep in mind that all ionic compounds are solids at room temperature ion-dipole interactions -- remember this chart:non-polar covalent bond EN = 0.0 - 0.4polar bond EN = 0.4 - 2.0ionic bond EN > 2.0 dipole-dipole interactions -- occur between polar covalent compounds; each element in a Lewis structure can be labeled as partial + (+) or partial negative (-) hydrogen bonding -- occurs between a hydrogen and either 2 oxygens, 2 nitrogens, or 2 fluorines; must look like one of the following: O-H-O, N-H-N, or F-H-Fintermolecular forces increase with increasing molar mass, but all hydrogen bonds (H with N, O, or F) are still stronger, regardless of molar mass! London dispersion forces -- the weakest bonds; present in all compounds; only important in non-polar compounds since these are the only forces present in non-polar compounds; a very temporary induced dipole3 Viscosity (The Liquid State) viscocity -- resistance to flow; one measure of the forces of attraction within a liquidhoney and glycerin are viscous liquids (i.e., they have high viscocities)4 Surface Tension (The Liquid State) surface tension -- a measure of the inward forces that must be overcome to expand the surface of a liquid; molecules on the surface are attracted only toward the interior, while those in the interior are attracted equally in all directions5 Capillary Action (The Liquid State) cohesive forces -- the forces that hold a liquid together adhesive forces -- the forces between a liquid and another surface capillary action -- water drawn up through the roots of plantscapillary rise -- implies that adhesive forces > cohesive forcescapillary fall -- implies that cohesive forces > adhesive forces6 Evaporation (The Liquid State) temperature dependent -- as temperature increases, the amount of evaporation increases as well () gas particles in an open beaker DO NOT have a vapor pressure of zero; they have a vapor pressure equal to atmospheric pressure in a sealed container, vapor pressure is created by gas particles colliding with each other and the sides of the container7 Vapor Pressure (The Liquid State) due to intermolecular forces, the amount of vapor and the boiling point both increase as you make your way DOWN the following chart:vapor pressures for three common liquidscompoundnametype ofbonds0 oC 25 oC 50 oCnormalboilingpointdiethyl etherCH3OCH3dipole-dipole185 torr 470 torr 1325 torr 36 oCmethanolCH2CH2OHhydrogenbonding29.7 torr 122 torr 404 torr 78 oCwaterH2Ohydrogenbonding4.6 torr 23.8 torr 92.5 torr 100 oC*note that the C–O bond is weaker than the O–H bond because of the incredible strength of hydrogen bonds8 Boiling Points and Distillation (The Liquid State) boiling point -- the temperature at which the vapor pressure of a liquid equals the applied (usually atmospheric) pressurein the chart below, HF has a much higher boiling point in relation to its molecular weight than HCl, HBr, and HI because HF has hydrogenbonds, while HCl, HBr, and HI are all dipole-dipolecompound molecular weight boiling pointHF 20 amu 19.5 oCHCl 37 amu -85.0 oCHBr 81 amu -67.0 oCHI 128 amu -34.0 oCso, hydrogen bonding liquids have abnormally high boiling points normal boiling point -- the temperature at which the vapor pressure of a liquid equals 760 torr (1.00 atm) distillation -- the process by which a mixture or solution is separated into its components on the basis of differences in boiling points of the componentssee drawing in lecture outline!9 Heat Transfer Involving Liquids (The Liquid State) specific heat -- (J/g · oC or Cal/g · oC) the amount of heat required to raise the temperature of 1.00 g of a substance 1 oC, with no change in stateQ = m C T  see lecture outline to see when to use each equation!*note that T is an absolute value, meaning it is ALWAYS positive (+)! molar heat capacity -- the amount of heat required to raise the temperature of 1.00 mol of a substance 1 oC, with no change in stateQ = (mol)(J/mol · oC)(T) heat of vaporization -- (J/g) the amount of heat that must be absorbed toconvert 1.00 g of a liquid at its boiling point to a gas with no change in temperature+J  endothermic, adding heat, energy flows into the system heat of condensation -- (J/g) the reverse of the heat of vaporization; the amount of heat that must be removed to liquefy 1.00 g of a gas as its condensation (boiling) point with no change in temperature-J  exothermic, removing heat, energy flows out of the system molar heat of vaporization,  H vap -- (J/mol) the amount of heat that must be absorbed to convert 1.00 mol of a liquid at its boiling point to a gas with no change in temperature molar heat of condensation,  H con -- (J/mol) the reverse of the molar heatof vaporization10 Melting Point (The Solid State) normal melting point -- the temperature at which the solid melts (liquid and solid are in equilibrium) at exactly 1.00 atm of pressure; this increases as the strength of the intermolecular attractions increases ()11 Heat Transfer Involving Solids (The Solid State) heat of fusion,  H fusion -- (J/g) the amount of heat required to melt 1.00 gram of a solid at its melting point at constant temperature*note that melting (solid  liquid) is