CHEM 108 1st Edition Final Exam Study GuideChapter 10:Intermolecular ForcesIntermolecular attractive forces affect physical properties of substances:- Ion-ion interactions:Strongest kind of intermolecular force, this is because the particles in an ionic compound have opposite charges so their force of attraction is much greater.- Ion-dipole interactions:Interaction between an ion and the partial charge of a molecule with a permanent dipole. These interactions cause molecules to dissolve in water.- Dipole-dipole interactions: Interaction of two molecules that have permanent dipole moment, i.e. polar molecules. Permanent dipole moments happen due to the difference in electronegativities in two atoms in a compound.- Hydrogen bonds Special class of dipole-dipole interactions due to strength, and it requires H atom covalently bonded to strongly electronegative atom. Example: F, O, NThese are the strongest dipole-dipole interactions- Dispersion forces (London forces)These forces are attractive forces between non-polar molecules, it works because of the instantaneous dipole on one molecule which induces dipole on another molecule. The instantaneous dipole is caused due to momentary changes in the electron distribution in an atom. These forces exist in all molecules, regardless of polarity.- Dipole-induced dipole interactionsInduced dipole is when a polar molecule repels or attracts the electrons of another atom inducing a temporary dipole in that atom. Occurs when polar molecules interact with non-polar molecules. - An increase in intermolecular force means:• increase boiling point • decrease vapor pressure • increase melting point • increase surface tension • increase viscosity- Boiling pointThe boiling point is the temperature at which the vapor pressure is equal to the pressure on the liquid, usually atmospheric pressure.- SolubilitySolubility depends on relative strength of solute-solvent interactions, which also means that solubility will increase as polarity increases. Like dissolves Like: - Henry’s Law: The solubility of a sparingly soluble chemically unreactive gas is proportional to the partial pressure of the gas: Cgas = kH*Pgas- The solubility of a gas (Sgas) is directly proportional to its partial pressure, (Pgas) Sgas = kH*Pgas- Phase diagram: o A graphic representation of the stabilities of physical states of a substance as a function of temperature and pressure. o Equilibrium lines represent phase changes between solid/liquid, liquid/gas, and solid/gas under specific conditions (T, P).o Triple point: Temperature/pressure where all three phases coexist. o Critical point: Specific temperature/pressure at which the liquid and gas phases have the same density.o Supercritical region: fourth state of matter with properties intermediate between gas and liquid. It’s where Supercritical fluid exists; it’s a substance above its critical temperature and pressure. It has the density similar to that of a liquid but can penetrate materials like a gas and dissolve substances in them like a liquid.o The slope of the lines represents the density of the substance at any given point onthe line.o The phase diagram is different for different substances due to their unique chemical properties.Chapter 11Solutions: Properties and Behavior:Vapor pressure: - Pressure exerted by a gas in equilibrium with its liquid, when rates of evaporation and condensation are equal (Dynamic equilibrium)- A system in dynamic equilibrium can respond to changes in the conditions o Temperature: • Higher temperature = higher kinetic energy; more molecules with sufficient Ek to overcome attractive forces in liquid phase. o Surface Area: • Higher surface area = greater number of molecules in positionto enter gas phase. o Intermolecular Forces: • Stronger forces = higher Ek needed to enter gas phase.- Raoult’s Law:o Vapor pressure of solution is proportional to mole fraction of solvent (non-volatile solute). o Psolution = Xsolvent * PsolventWhere x is the mole fraction of the solvento Ideal Solutions are solutions that obey Raoult’s Law.- Colligative Properties: Solution properties that depend on concentration of solute particles, not the identity of particles.- Enthalpy of Solution:To make a solution you must:o overcome all attractions between the solute particles (breaking bonds require energy ); therefore ΔHsolute is endothermic o overcome some attractions between solvent molecules (breaking some bonds also require energy);therefore ΔHsolvent is endothermic o form new attractions between solute particles and solvent molecules (formingbonds releases energy); therefore ΔHmix is exothermic o The overall DH for making a solution depends on the relative sizes of the DHfor these three processes  ΔHsolution= ΔHsolute+ ΔHsolvent + ΔHmix- Dissolution of Ionic Solids: Enthalpy of solution (ΔHsolution) depends on: o Energies holding solute ions in crystal lattice (endothermic)o Attractive force holding solvent molecules together (endothermic)o Interactions between solute ions and solvent molecules. (exothermic)o ΔHsolution = ΔHion-ion + ΔHdipole-dipole + ΔHion-dipole ΔHdipole-dipole + ΔHion-dipole= ΔHhydration- Born-Haber Cycle: Algebraic sum of enthalpy changes associated with formation of ionic solid from constituent elements. o E.g., Na(s) + ½ Cl2 (g) → NaCl(s) ΔHf ° = −411.2 kJ- Steps: o 1. sublimation of 1 mole Na(s) → Na(g) = ΔHsublimationo 2. breaking bonds of ½ mole of Cl2 (g) = ½ ΔHBEo 3. ionization of 1 mole Na(g) atoms = IE1 (Ionization energy)o 4. ionization of 1 mole Cl(g) atoms = EA1 (Electron Affinity)o 5. formation of 1 mole NaCl(s) from ions(g) = Uo ΔHf ° = ΔHsub + ½ ΔHBE + IE1 + EA1 + U- Mixtures of volatile solutions:For mixtures containing more than one volatile component: o Partial pressure of each volatile component contributes to total vapor pressureof solution. Ptotal = X1P1 ° + X2P2 ° + X3P3 ° …o Where Xi = mole fraction of component i, and Pi ° = equilibrium vapor pressure of pure volatile component at a given temperature.- Solute Concentration: Molality:Changes in boiling point/freezing point of solutions depend on molality: o m=(nsolute/ kg solvent)- Preferred concentration unit for properties involving temperature changes because it is independent of temperature. - Boiling Point Elevation (ΔTb ): o ΔTb = Kb ∙mo Kb = boiling point elevation constant of solvent; m = molality.o Kbof water = 0.51 °C