CHEM 2200 1nd Edition Exam 1 Study Guide Lectures 1 7 Lecture 1 August 21 Equations o Ideal Gas Law PV nRT o Clausius Clapeyron Equation lnP2 vapH 1 1 lnP1 R T2 T1 In real gasses not ideal intermolecular forces are at work Four kinds of IMF s o Hydrogen Bonding o Dipole dipole forces between molecules with permanent partial charges o Ion ion forces between ions o London Dispersion forces between nonpolar molecules occurs in ALL bonding situations two induced dipoles The greater the forces of attraction between molecules the greater the energy that must be applied to separate them Boiling point increases with atomic mass but molecules with greater charges will have higher boiling points Hydrogen bonding molecules to not follow that molar mass trend for boiling point they have much higher boiling points due to the large electronegativity charges Hydrogen bonding explains why water has such a high boiling point and is lower in density in the solid form Polar molecules can create a temporary dipole in nonpolar molecules Vaporization the process in which a substance in the liquid state becomes a gas Vaporization is an endothermic process Condensation is the reversed process of vaporization enthalpy change is equal but opposite in sign to that of vaporization Vapor pressure is created when there is a liquid in a closed container and some of its molecules are changing to the gas form o Can be measures one the two liquids reach equilibrium Normal Boiling Point is the temperature at which the external pressure is 760 mmHg o Normal boiling point for water is 100 C Molecules at the surface of liquids only interact with molecules at or immediately around the surface reason for surface tension Viscosity increases with increasing molecule size Unit cell smallest repeating unit that makes up a solid o Primitive cubic just the four corner molecules Total atoms 1 o Body centered cubic has an additional particle same type as in corners in the center of the cube Total atoms 2 o Face centered cubic additional particle on each of 6 faces Total atoms 4 Semiconductors are given their name because they do not conduct electricity easily but can be prompted to do so by the input of energy o Contain a band gap between molecular orbital bands Gap acts as a barrier to keep electrons from entering the higher energy state o P type semiconductor a semiconductor where positive holes can appear o N type semiconductor a semiconductor consisting of negative charge carriers Lattice Energy a way to measure the strength of the bonding in an ionic crystal lattice high strength high melting point o Lattice energy comes from the energy of formation of one mole of the compound Lattice enthalpy o Has a larger negative value for more highly charged ions o The smaller the ions in the lattice the more negative their enthalpies Melting points increase with increasing molar mass KNOW how to interpret a phase diagram Molarity M moles of solute moles of solvent Molality m moles of solute Kg of solvent When a solution is saturated no more of the solid placed in the solvent will dissolve and the concentration of the ions of the solute will not increase Solubility the concentration of solute in equilibrium with un dissolved solute in a saturated solution Miscible when liquids mix to an appreciable extent to form a solution Immiscible when liquids do not mix to form a solution Factors that affect solubility Pressure and Temperature o With an increase in pressure more molecules are able to reenter the liquid phase in a given period of time o Solubility of all gas decrease with increasing temperature Colligative properties properties that depend on the relative number of solute and solvent particles in a solution and not their identity o Vapor pressure o Boiling point elevation o Freezing point depression o Osmotic pressure True solution a solution in which the solute does not settle and solute particles should be in the form of ions or relatively small molecules Suspension solute settles to the bottom Emulsions colloidal dispersions of one liquid in another Surfactant affects the properties of surfaces and affect the interaction between two phases o Surfactants use for cleaning are called detergents Chemical kinetics a study of the rate of chemical reactions Reaction mechanism the detailed pathway taken by atoms and molecules as a reaction proceeds Rat of reaction concentration time The longer after a reaction has begun the slower the rate will be