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Exam one Study Guide Chemistry 1212
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Popular in Chemistry
This 6 page Study Guide was uploaded by Lauren Dennis on Tuesday September 27, 2016. The Study Guide belongs to Chemistry 1212 at Georgia State University taught by Dr. Doyle in Fall 2016. Since its upload, it has received 12 views. For similar materials see Chemistry 1212 in Chemistry at Georgia State University.
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Date Created: 09/27/16
Chemistry Study Guide Bonds Electrostatic: the ability of an object to acquire an electron o Holds matter together o Trend on the Periodic Table: Increases going down the columns Increases going across the rows Phases: solid, liquid, and gas o Spacing between molecules Gas > Solid > Liquid Forces: o London (induced dipole) Every molecule have these forces Very weak Larger molecular weight = more electrons Larger the molecule = Stronger the force BP determined by molecular weight Ex. CH4, CH3CH, CH3CH2CH3 CH3CH2CH3 > CH3CH > CH4 o If they are similar Molecules As the force increases so does the boiling point, bp Lowers the density Lowers the melting point Dipole – Dipole Interactions o Occurs only between polar molecules Water or H2O o Ex. CH4, CH3F, CF4 CH4: NONPOLAR CH3F: POLAR Dipole- Dipole High BP and MP CF4: NONPOLAR London Polar bonds, but are symmetrical Van der Waals o The category of forces Include: London and Dipole-Dipole o Short Range of Forces o Very Weak o Very few interactions between molecules Hydrogen Bonding o Similar to dipole- dipole o Not a “real” bond o Need: H-F, C-H, C-O, O-H Hydrogen Bond Donor o Lone Electron Pair Hydrogen Bond Acceptor H o Ex. CH3FOH to NH3 N H H H C O H H Ion Dipole o Strongest forces o Only found in solutions o The molecule “dissolves” Breaks down to their original components Ex NaCl dissolved into H2O o Na+ and Cl- o Ionic Solution o “Like dissolves Like” Polar with Nonpolar: Oil/H2O o Need an ion/dipole: ionic substance o Larger the charge = the greater the interaction ION > HYDROGEN > DIPOLE- DIPOLE > DISPERSION (LONDON) PROPERTIES o Boiling point: the vapor pressure = the atmospheric pressure o Melting point: the temperature at which a given solid will melt o Surface tension: energy required to increase surface area o Heat of vaporization: the energy required to change a liquid into a gas o Vapor pressure: the pressure of a vapor when in contact with a liquid or a solid o Visocity: resistance to float Lower molecular forces = tend to float Motor Oil o Capillary action: ability to flow upward Forces between tube and substances Example of the Heat of Vaporization: o Heat (q) in KJ to vaporize 2.58 kg of H2O Bp = 100 C Heat of Vaporization = 40.7 KJ/mol q= Heat of Vaporization x moles(n) (40.67KJ/mol)(143mol) = q q= 5820 KJ Temperature Change: o Change in Temperature = (q)(SH)(m) q= heat SH= specific heat m= mass Change in Phase o Change in Vaporization = - Change in Condensation o Change in Fusion - - Change in Freezing o Change in Sublimation = (Change in Fusion) + (Change in vap.) o Change in Disposition = _____ - (Change in Sublimation) Phase Diagrams Ga Properties MP BP Surface Visocity Vapor Heat of s Tension Pressure Vaporization London Lowest Lowest Lowest Lowest Highest Lowest Dipole – Lower Lower Lower Lower Higher Lower Dipole Hydrogen Low Low Low Low High Low Bonding Ion Dipole Highest GaHighest Highest Highest Lowest highest s Liqui d Soli d Dynamic Equilibrium: a flat line; no change in temperature o Solid – Liquid o Liquid – Gas Solid is found at lower temperatures Gas is found at higher temperatures Solid – Liquid: melting point Liquid – Gas: boiling point Liqui Soli d d Ga s o Where the three lines meet: TRIPLE POINT o Where it goes from solid to liquid: N. MELTING POINT o Where it goes from liquid to gas: N. BOILING POINT o CRITICAL POINT: the liquid to solid phase does not exist; the molecule becomes cloudy It is at the tip of the line dissecting from liquid to gas Clausius – Clapeyron Equation: o Ln(Pvap) = ((-Heat of Vaporization)/(R))(1/T) + lnB What is the equation? Y = mx + b o Ln(P2/P1) = ((-Heat of vap.)/(R))((1/T2)-(1/T1)) All pressures in either torr or atm All temperatures in Kelvin All Heat of vaporization in J/mol R = 8.314 J/molK Cubics: o Simple/ Primitive 1 atom total 1/8 of the atom is in each corner of the square o Body Center 2 atoms total 1 in the center and 1/8 in each corner o Face Center 4 atoms total ½ atom on each face and 1/8 in each corner Energetically favorable Compounds in a solution dissociate into the molecular components o Must disrupt the network; to break the bonds = to form new interactions with H2O = Solution o It is unfavorable to disrupt the bonds = higher energy 2 types of favorable forming solutions: o Change in enthalpy increase o Change in entropy decrease Disorder More disorder = very favorable 2 substances that form a homogensis mixture: o Solid/liquid: NaCl and H2O o Gas/gas: Air (Nitrogen and Oxygen) o Liquid/ liquid: Vodka and H2O o Gas/ liquid: Soda (CO2 and HO) o Solid/ solid: brass 2 parts to a Solution: o Solute: substances present in lesser amounts o Solvent: a substance in the greatest amount in the solution Solubility: whether one substance dissolves in another o Miscible o “like dissolves like” intermolecular forces at work o Example: Which compounds are soluble in Hexane (CH3CH2CH2CH2CH3)? London forces present o (1): H2O “hydrogen bonds” = NOT o (2) CH3CH2CH3 “London” = SOLUBLE o (3) HCl “dp-dp” = NOT Equilibrium: point of even; both substances are dissolved with no excess o Saturated: no more solute in a solution o Unsaturated: more solute can go into the solution o Supersaturated: unstable; solution can fall out easily Things to Know: o Most of the time solubility of solids increase with temperature o Most of the time solubility of gases decrease with temperature o Most of the time solubility of gases increase with pressure Henry’s Law: o Solubility of a gas is dependent on temperature o S gas= K h gas Khis a constant that every gas has o Example: O2 at 25C with a pressure of air at 1atm P oxygen.21 atm K h 1.3 x 10 M/atm -3 o S o2(1.3 x 10 )(.21) = 2.7 x 10 M-4 o Expressing Concentrations: Molarity = (the mol of the solute)/(liters of the solution) = M Temperature dependent o Volume changes with temperatures There can be multiple molarities in a solution Molality = (mol of solute) / (kg of solvent) = m (X) Mole Fraction = (mol of solute) / (tot. mol of substances) Mole % = Mole Fraction x 100% Mass % = (Mass of solute)/ (total mass of solution) x 100 Density = mass/ volume o Rouault’s Law (Colligative Properties) Vapor Pressure of a liquid when adding to another substance Adding a NON-volatile to a volatile o Vapor Pressure will never go up o Will always go down o P solutionX x P solvent Adding volatile to volatile o P = X P + X P solution a a b b o Boiling and Freezing Point Depressions: Change in Temperature = m x K f or b m= molality K = freezing or boiling point constant o Osmotic Pressure: Travel through a semipermeable membrane without stress = MRT o M= molarity o R= .0821 o T= Temperature (kelvin)
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