Unit Nine Review

IMF Intermolecular forces The three states of matter depend on Attractive forces between molecules The three states of matter depend on Strength of IMF relative to the amount of thermal energy Weaker IMF Gas Stronger IMF Solid or liquid

IMF Surface tension Viscosity Volatile Dynamic equilibrium Tendency of liquids to minimize surface area Stronger IMF, greater surface tension Viscosity Resistance of a liquid to flow Stronger IMF, greater viscosity Volatile Easily evaporates Dynamic equilibrium Rate of condensation = rate of evaporation Vapors condensing = liquid evaporating Vapor pressure Pressure exerted by a liquids vapor molecules

Phase Change Boiling occurs throughout the liquid Evaporation occurs only at the surface Rate of Vaporization increases Increase surface area Increase temperature Decrease strength of IMF Vapor pressure increases Make a liquid boil Decrease atm pressure (lowers bp) Make a gas condense Decrease temperature Increase atm pressure Melting Solid to liquid Freezing Liquid to solid Boiling Liquid to gas Condensation Gas to liquid Sublimation Solid to gas Deposition Gas to solid

Calculations Be able to use the Heat of vaporization (boiling/condensing plateau) Heat of fusion (melting/freezing plateau) Specific Heat (slope) q=mCΔT equations to calculate the energy required

Types of IMF Dispersion Dipole – Dipole Hydrogen Bonds Temporary uneven distribution of electrons Molar mass Symmetry Surface area Dipole – Dipole Permanent uneven distribution of electrons Hydrogen Bonds H bonded to N, O, or F

Solids Molecular Covalent Metallic Ionic Neutral corners Low melting points NM & NM M & ML or ML & NM Covalent High melting points ML & ML Metallic Positive ions (cations) M & M Ionic Positive and negative ions (cations and anions) M & NM

Water Why is water unique? Hydrate calculations (Worksheet 4)