EXAM I STUDY GUIDE CHAPTERS 11 13 CHAPTER 11 INTERMOLECULAR FORCES PHASES The kinetic molecular theory Intermolecular forces vs intramolecular forces Different types of intermolecular forces IMFs Dipole dipole Dipole induced dipole London dispersion forces Ion dipole attraction Hydrogen bonding Surface tension Cohesion Adhesion Viscosity Phase change States that energy comes from temperature Gases gases are governed by this theory with assumptions that it is an ideal gas where distance between atoms is big the gas has free motion and is temperature dependent Liquids Solids depends of 2 major parts temperature and intermolecular forces IMF forces between molecules more than 2 molecules Intra hold a single molecule together much stronger than IMF Van der waals dipole dipole dipole induced dipole London dispersion forces electrostatic forces dipole ion attraction hydrogen bonding Results from molecules having a dipole moment different electonegativites polar molecule creates stability because the negative part of one molecule lines up with the positive part of another and holds them together Between nonpolar molecules and a polar molecule the non polar molecules when lined up with the polar create a diffrent electron cloud distribution and an induced dipole is formed either negative or positive depending on where the molecule is relative to the polar molecule Greater number of electrons easier to polarize Temporary forces created by movement of electrons predominant in nonpolar molecules Weakest of the IMFs Most occurring all have this and can also be additive Happens because all electrons have free flowing motion and when they move they have brief interactions with other molecules Attraction of an ion and a polar molecule Ex is hydration when an ion is surrounded by water molecules and attracted to the positive end of the polar molecule when an anion and the negative end of polar molecules when a cation Strong IMF between the H atom in a polar bond and an O N or F atom that has a lone pair More hydrogen bonds a molecule has the higher the boiling point Amount of energy required to increase the surface of a liquid Stronger IMFs stronger surface tension Attraction to similar molecules Attraction to different molecules Measure of a fluid s resistance to flow usually changes with temperature Stronger IMF higher viscosity A high viscosity means it does not flow well Transformation from one phase to another Usually energy is added or removed from a substance Physical changes characterized by changes in molecular order EXAM I STUDY GUIDE CHAPTERS 11 13 Evaporation vaporization Condensation Vapor pressure Dynamic equilibrium Molar heat of vaporization Equations to find this Clausius Clapeyron equation When molecules of a liquid have enough energy to break from their IMFs the liquid changes to a gas LIQUID TO GAS More temperature greater kinetic energy more molecules leave the liquid and turn into gas When a gas converts back to a liquid GAS TO LIQUID Depends on 2 things temp and IMFs Vapor pressure pressure exerted on solution by molecules that a evaporating Rate of forward reaction rate of reverse reaction Ex rate of evaporation rate of condensation Energy required to vaporize 1 mole of a liquid The strength of the IMFs can be predicted using this the stronger the IMF the higher the Hvap which means it is hard to vaporize Ln P Hvap RT C Where R is gas constant 8 134 J mol K and C is a constant Use this equation when graphing in y mx b format where y ln P m Hvap R x 1 T and b C Plot ln P vs 1 T and the slope will equal Hvap R will also give a straight line Steeper the slope higher value of delta Hvap Another equation to use When you have 2 temperatures pressures Boiling point 2 ways to condense a gas Critical temperature TC Critical pressure PC Melting point Freezing point Heating curve Ln P1 P2 Hvap R 1 T1 1 T2 or Ln P1 P2 Hvap R T1 T2 T1 T2 Temperature where vapor pressure external pressure Higher IMF higher boiling pt Reduce the temp and raise the pressure but there are 2 important conditions that coincide with this Temp where a gas cannot condense Temp is so high it will not form and condense no matter how strong the IMFs Minimum pressure that can condense a gas near Tc This is right below the point of Tc min pressure to make it condense until it won t condense any more when it reaches the actual Tc Temperature of solid to liquid conversion Temperature for liquid to solid conversion Illustrates heat energy added and the temperature EXAM I STUDY GUIDE CHAPTERS 11 13 Molar heat of fusion Sublimation Deposition Molar heat of sublimation Phase diagram Energy required to melt one mole of a solid Hfus SOLID TO GAS GAS TO SOLID Hsub energy required to sublime 1 mole of a substance Hsub Hfus Hvap for problems that you need to use this concept you have to use the heat equation q ms T for the different phases in the problem Visual summary of the conditions at which a substance exists in the various phases Triple point When you cross a line it is a phase change Only condition under which all phases can be in equilibrium Where all three curves intersect EXAM I STUDY GUIDE CHAPTERS 11 13 CHAPTER 12 SOLUTIONS Saturated Unsaturated Supersaturated Crystallization Liquid gas liquid solid liquid liquid saturated supersaturated unsaturated Contains the max amount of solute that will dissolve in a solvent at a specific temperature All solute you are allowed to use Contains less solute than it has capacity to dissolve Contains more solute than is present in a saturated solution very unstable When a dissolved solute comes out of solution supersaturated and forms a crystal What is dissolved in a solution Dissolves the solute Solute solute solute solvent solvent solvent Miscible IMFs vs Solubility Energy and disorder randomness Concentration Ways to measure concentration units Solute Solvent 3 interactions for a solution Solution is governed by 2 things Energy The H of spontaneous reactions are negative Disorder randomness When a solute and solvent are mixed much of the order organization is disrupted this increase in disorder entropy favors the solubility of any substance Like IMFs dissolve like species this means that two substances are more likely to interact if their IMFs are similar Substances that are completely soluble in each other in all proportions no saturation point Amount of solute present in a given solution Mass Mole fraction Molarity Molality Mass of solute g mass of solution g 100 Get mass
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