Equation sheet exam 2

Equation sheet exam - Chem 6B Exam 2 Equation Sheet Ideal gas law PV nRT Ch 8 The vapor pressure of a liquid is the equilibrium established at a

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Chem 6B Equation Sheet (Exam 2) 1 Prof. Crowell Chem 6B Exam 2 Equation Sheet Ideal gas law: P Vn R T Ch. 8: The vapor pressure of a liquid is the equilibrium established at a given temperature in which the rate of evaporation and rate of condensation become equal. The Boltzmann Distribution explains that the fraction of molecules with enough energy to escape the liquid is greater as the temperature increases. Types of Intermolecular Forces: Ion ± Dipole Interactions: Attractive interactions between charged ions and the oppositely charged end of a molecule with a permanent dipole moment. Dipole ± Dipole Interactions: Attractive interactions for molecules with a permanent dipole moment . Interactions can occur side-to-side or end-to-end. Hydrogen Bonding: A special type of dipole-dipole interaction. Only occurs for hydrogen bond to N, O, or F interacting with O, N, or F (e.g. F-H····F, O-H····F, N-H····F, etc.) Dispersion Forces: Also called London forces, London dispersion forces, Van der Waal forces, or induced dipole ± induced dipole forces. Dispersion forces depend upon the polarizability D (i.e. the relative degree the electron cloud on a molecule can be distorted). The distorted e- cloud results in a dynamic dipole. Dispersion forces depend upon (i) the number of electrons an atom or molecule has, and (ii) the length of the interaction. Ion ± Induced Dipole or Dipole ± Induced Dipole: An interaction between an ion or dipole and a temporary dynamic dipole moment caused by distortion of an e- cloud by the ²charged³ species. To change phases (i.e. melt, boil, sublime), or to escape a liquid and vaporize, one must break the intermolecular or interatomic forces between the molecules. The energy required to change phase depends upon the magnitude of the intermolecular forces involved. For Solids: Ion ± ion > ion ± dipole > H-bonding > dipole ± dipole § dipole ± induced dipole § London dispersion forces. For Liquids and Gases: ion ± dipole > H-bonding > London dispersion forces > dipole ± dipole > dipole ± induced dipole. The natural logarithm of the pressure is inversely proportional to temperature: [from ' G = ' G q + RT ln (P/P q ) ] ln vap vap vap GH S P RT R ±' ±' ' ² DD D with the resulting Clausius-Clapeyron Eqn: 2 12 1 11 ln vap H P P T ±' §· ± ¨¸ ©¹ D Phase diagrams: Each region depicts the temperatures and pressures under which the phase is stable. The lines between any two regions show the conditions at which the two phases exist in equilibrium. The critical point shows the conditions beyond which separate liquid and gas phases no longer exist. At the triple point, the three phases exist in equilibrium. The phase diagram for CO 2 is typical of most substances in that the solid-liquid line slopes to the right with increasing pressure: the solid is more dense than the liquid. Water is one of the few substances whose solid-liquid line slopes to the left with increasing pressure: the solid is less dense than the liquid. The phase rule 3 F p ± describes how many independent variables F
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This note was uploaded on 08/11/2011 for the course CHEM 140A taught by Professor Whiteshell during the Spring '04 term at UCSD.

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Equation sheet exam - Chem 6B Exam 2 Equation Sheet Ideal gas law PV nRT Ch 8 The vapor pressure of a liquid is the equilibrium established at a

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