Chemistry Exam 1 Study Guide
Chemistry Exam 1 Study Guide CHEM 1120
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This 8 page Study Guide was uploaded by Anzlee on Monday September 12, 2016. The Study Guide belongs to CHEM 1120 at Middle Tennessee State University taught by Ngee S Chong in Fall 2016. Since its upload, it has received 61 views. For similar materials see General Chemistry II in Chemistry at Middle Tennessee State University.
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Date Created: 09/12/16
EXAM 1 STUDY GUIDE Prerequisites to Review *Remember how to do Lewis Dot Structure *Review of Group Names on Period Table: 1A/1- Alkali Metals 2A/2- Alkali Earth Metals 6A/16- Chalcogens 7A/17- Halogens (Diatomic) 8A/18- Noble/Inert Gases *States at Room Temperature: Gas: Mg and Br Liquid: Fr, Cs, Gr, and Rb Solid- all others *Solubility: -Solute- what’s going into solvent; smaller number of moles -Solvent- dissolves solute; larger number of moles -Solubility- maximum amount of substance it can dissolve at a given volume -Miscible- liquids are mutually soluble in any proportion Chapter 6 Intermolecular Forces • Interactions between nonpolar molecules o Dispersion- momentary shift in electron density o Dispersion (London) forces- caused by presence of temporary dipoles in molecules (weakest bond) § Larger molecules usually solid, then liquid, then gas o Temporary (induced) dipole- separation of charge produced in atom or molecule by a temporary uneven distribution of electrons (middle strength) § May be caused by a reaction between a polar and nonpolar molecule o Polarizability- the ease that an electron cloud in a molecule, ion, or atom can be distorted, inducing a temporary dipole § Larger molecules/elements have higher polarizability because intermolecular forces are weaker Factors Affecting Strength of Dispersion: • Size of atom/molecule- larger are more polarizable because the outer valence electrons are being weakly pulled by the positive nucleus; dispersion increases with polarizability o Molar mass size is directly correlated with boiling point/melting point o RVP: reid vapor pressure of gasoline regulated by Environmental Protection Agency • Shape of molecules- increased surface area causes increased interactions and stronger interactions, which affects physical and chemical properties; linear molecules have higher dispersion than branched molecules with similar molecule weight o Constitutional isomers (structural isomers)- molecules that have the same formulas, but different connections between atoms; differently arranged o Larger surface = larger dispersion = higher boiling point o Viscosity- measure of resistance of a fluid to flow (cP- centipoise unit) § factors: molecular shape, molar mass, and temperature § higher molar mass= higher viscosity Interactions Involving Polar Molecules: • Dipole-dipole attraction- the force between polar molecules • Hydrogen bond- strongest dipole-dipole interaction o occurs between hydrogen bonded to a small and highly electronegative element (F, O, N) and an atom of O or N in another molecule o Ex. between complementary sites on double stranded DNA- between A and T or C and D o All alcohols; all amino acids can have hydrogen bonds o More hydrogen bonding = higher boiling point • Boiling points of Binary Hydrides- when boiling points are related to attractive forces, be able to determine boiling point order • Ion-Dipole- force between an ion and a molecule with a permanent dipole • Sphere of hydration- water molecules surrounding ion in aqueous medium Solubility: • Depends on relative strength of interactions between molecules • Ionic/polar solutes are soluble in polar solvents o No solution if different forces • Nonpolar solutes are soluble in nonpolar solvents o No solution if different forces • More than one force may need to be examined o Solubility decreases as hydrogen bonding energy decreases and dispersion increases • Hydrophobic- repels water; lowers solubility • Hydrophilic- attracts water; heightens solubility Physical States: • Factors that affect state: intermolecular forces, temperature, pressure • Phase diagram o Graphical representation of substance’s states depending on temperature and pressure o Lines represent points where two states on either side coexist in equilibrium o Triple point- where all phases exist at same time o Critical point- where liquid and gas have same density o Supercritical fluid- substance above critical temperature and pressure Properties of Water: • Surface tension- energy needed to separate molecules of the liquid’s surface; directly correlates with strength of intermolecular forces • Cohesion- interactions between same particles • Adhesion- interactions between different particles • ex. meniscus § concave- adhesive forces greater than cohesive forces § convex- cohesive forces greater than adhesive forces • Capillary action- liquid can spontaneously flow against gravity; involves adhesive and cohesive forces • Density of water- decreases as a solid o Important for aquatic ecosystems Chapter 11 Properties of Solutions • Enthalpy of Solution depends on: o Energies that are holding the solute ions in the crystal lattice o Attractive force holding solvent together o Interactions between solute ions and solvent molecules • Lattice energy- energy released when 1 mole of the ionic compound forms from free ions in gas phase; energy released when crystal lattice forms (positive) • ΔH ion-ionenergy required to remove ions from crystal lattice (negative) • Born-Haber cycle- series of steps with change of energy (ΔH) that describe the formation of an ionic solid from its elements (sublimation, bond breaking, ionization, electron affinity, formation) Isoelectronic- same electron configuration when electrons are lost or gained Na is isoelectronic with Ne Vapor Pressure: • Pressure exerted by gas in equilibrium with liquid; evaporation and condensation rates are equal • Normal boiling point- ambient pressure must be standard pressure • Factors affecting vapor pressure: o Temperature/surface area; overcoming intermolecular forces o Presence of nonvolatile solute- affects rate; decreases vapor pressure o Clausius-Clapeyron Equation: related vapor pressure with temperature of substance to its heat of evaporation • Fractional Distillation- separate a mixture of compounds based on their differing boiling points o More volatile components have enriched vapor pressure • Raoult’s Law- total of overall pressure is equal to the sum of each individual pressures of the components, in an ideal solution • Real vs. Ideal solutions- due to differences in solvent-solvent and solvent-solute interactions Osmosis: • Fluid flows across a semipermeable membrane to balance the concentration of that fluid on both sides • Osmotic pressure- pressure applied to membrane to stop flow of solvent o Formula: iMRT • Hypertonic state- water migrates out • Hypotonic state- water migrates in • Isotonic state- water concentration is at equilibrium o Cells within body should be isotonic • Reverse osmosis- solvent pushed through membrane, leaving higher concentrated solution behind o Ex. water distillation/purification Chapter 11 Online Homework Samples: 8, 16, 18
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