Chemistry 1220 Final Review CHAPTER 11 Ion dipole exist between an ion and the partial charge on the end of a polar molecule o Increase with charge of ion o Increase with magnitude of dipole based on electronegativity Dipole dipole exists when polar molecules are close together o Increase with increasing polarity difference in electronegativity o Nonpolar bond no dipole moment London Dispersion Van der Waals Forces A very weak interaction formed by the uneven electron cloud in a molecule o Increases with increasing polarizability electron cloud is distorted Polarizability The ease at which an induced dipole can occur o Increases with size or molecular weight Bigger more electrons more polarizable larger dispersion forces o Strength of dispersion force depends on Number of electrons more increase London Force Distance from the nucleus farther from the nucleus more polarizable greater force Size shape of molecule increases with increasing size o All molecules have some type only type in nonpolar molecules Hydrogen Bond Hydrogen atom bonded to N O F atom o Also a dipole dipole interaction o Very strong H bond Ion Dipole Dipole Dipole London Dispersion o All of these interactions are considerably weaker than covalent and ionic bonds At room temperature o I2 is a solid o Br2 is a liquid o Cl2 is a gas Condensed Phase Solid and Liquid o Particles in both solids and liquids are fairly close together Uncondensed Phase Gas o Weak forces between molecules Solids strongest IMF Gases weakest IMF Increasing IMF o Decreasing temperature decreases kinetic energy increasing o Increasing pressure forces molecules closer together increasing attractive forces attractive forces Viscosity The resistance of a liquid to flow o Increase IMF increases viscosity o Increase temperature decreases viscosity as temperature increases particles move faster not as attracted to each other o Increase molecular weight increases viscosity o More hydrogen bonds increased viscosity Surface Tension Property of a liquid that prevents it from spreading out o As temperature increases surface tension decreases o Increase IMF increases surface tension Cohesive Forces IMF that bind similar molecules to one another Adhesive Forces IMF that binds substances to a surface Solid Liquid Melting endothermic o Increase temperature increases kinetic energy until kinetic energy IMF o Hfus heat required to melt one mole of solid Liquid Solid Freezing Liquid Gas Vaporization endothermic Hvap heat required to convert one mole of liquid to vapor o o Tends to be larger than Hfus because it takes more energy to go from liquid to gas because molecules must be pulled apart Gas Liquid Condensation Solid Gas Sublimation Gas Solid Deposition Dynamic Equilibrium When the rate of vaporization equals the rate of condensation Vapor Pressure The pressure exerted by its vapor when the liquid and vapor are in dynamic equilibrium o Increase IMF decreases vapor pressure o Increase temperature increases vapor pressure o Boiling Point Where vapor pressure atmospheric pressure Strong IMF high boiling point low vapor pressure Weak IMF low boiling point high vapor pressure Normal Boiling Point The boiling point of a liquid at 1 atm of pressure Heating Curve o First slant ice o First plateau Hf melting o Second slant liquid o Second plateau Hv vaporization o Third slant steam o Heat capacity affects slope Finding Heat Needed to Melt Boil a Substance o Find difference in temperature and boiling or melting point o Find q g x SH x T from part 1 o Convert this answer to kJ o Convert grams to moles o Multiply moles by molar heat of fusion vaporization Supercooling Heat is removed so quickly that molecules have no time to assume ordered solid structure Critical Temperature The highest temperature at which a distinct liquid phase can form o Critical Pressure Pressure required to bring about liquification at this critical temperature o Greater IMF higher critical temperature Supercritical Fluid When a temperature exceeds critical pressure liquid gas phases are indistinguishable and substance is in a state called supercritical fluid Volatile Liquids that evaporate readily Vapor Pressure Curve Equilibrium between liquid and gas o Ends at critical point 0 beyond supercritical fluid Sublimation Curve Separates solids from gases and represents change in vapor pressure as it sublimes Melting Curve Separates solids from liquids and changing melting point of solid with increasing pressure o Usually slopes right because solid is denser than liquid o Melting curve for water slants to the left indicating water melting point decreases with increasing pressure because water in liquid is more compact than in solid o Increasing pressure can decrease the melting point Triple Point All three phases in equilibrium CHAPTER 13 Miscible Mix or dissolve in all proportions o To be miscible with water you must have strong enough interactions to overcome the nonpolar portion of the molecule Immiscible Form multiple layers Solvation Interaction between solute and solvent molecules Hydration Water is the solvent o Favorable Hsolution Hsolvent Hsolute Hmixture Hmixture Hsolvent Hsolute Hsolution is negative Hmixture Hsolvent Hsolute Hsolution is positive o Unfavorable Hsolution is positive o Lattice Energy LE Energy of Hydration HE Overall Energy Overall energy of a system van still decrease if the system becomes more disordered Solution Spontaneity and Formation o Intermolecular Forces o Energetics o Entropy randomness disorder Saturated A solution in equilibrium with undissolved solute o The point at which no more solute can be dissolved A solution that is in equilibrium with undissolved solute Unsaturated Contains less solute than the equilibrium amount Supersaturated Solvent holds more solute than is normally possible at that temperature o Unstable if disturbed will grab onto whatever possible to get out of Concentrated Solution Contains a larger amount of solute for a given solution amount of solvent Dilute Solution Contains a smaller amount of solute for a given amount of solvent Solubility The concentration of a solute in a saturated solution o The stronger the interactions are between solute and solvent molecules the greater the solubility o Increasing temperature increases solubility o Ability to hydrogen bond increases solubility in water o Increasing the number of carbons in an alcohol causes the solubility to decrease Polar liquids dissolve in polar solvents o Polarity increases