General Chemistry Study Guide 2 Water Universal Solvent Oxygen very electronegative high tendency to attract electrons to itself partially negative electron rich partially positive electron de cient Hydrogen Polar Covalent Bond Dipole bent v shaped angular Hydration Spheres cations surrounded by negative pole oxygen anions surrounded by positive pole hydrogen Like dissolves Like charge to charge interaction allows the solute particles to be attracted to polar and ionic solutes dissolve well in polar solvents the solvent and allows it to dissociate in the solvent non polar solutes tend to dissolve well in non polar solvents generally not soluble in water sugar and alcohol exceptions contain polar groups in their structures immiscible not mixing phase interface boundary between two phases immiscible liquids Solution homologous mixture in which a dissolved material solute is uniformly distributed throughout some medium solvent Concentration solute solution Molarity mole solute 1 L solution Dilution c1V1 c2V2 Electrolytes Strong Electrolytes compound when dissolved in water generates an electrically conductive solution mobile charges completely ionizes into elemental Ions highly illuminated light bulb e g NaCl s Na aq Cl aq i 2 partially ionizes some ionic compounds less bright light bulb Weak Electrolytes e g NH4 2CO3 s 2NH4 aq CO32 aq i 3 Non Electrolytes usually covalent don t dissolve don t ionize Soluble Ionic Compounds 1 Group IA cations and Ammonium 2 Nitrates Acetates and Perchlorates 3 Chlorides Bromides and Iodides EXCEPT Ag Pb2 Hg22 Cu 4 Sulfates EXCEPT Ca2 Sr2 Ba2 Pb2 Insoluble Ionic Compounds Precipitates 1 Hydroxides 2 Carbonates and Phosphates 3 Sul des EXCEPT Group IA and lower Group IIA starting with Ca2 EXCEPT Group IA and Ammonium EXCEPT Group IA Group IIA and Ammonium Total Ionic Equations shows all compounds in the reaction dissociated into ions EXCEPT gasses liquids and solids precipitates Net Ionic Equations shows only the ions of compounds in the reaction that produce a non aqueous compound spectator ions eliminated Acid Base Arrhenius acids produce hydronium ion bases produce hydoxide ion Bronsted Lowry acids donate protons H bases accept protons Lewis acids accept electron pairs bases donate electron pairs Amphoteric species can act as both acid and base e g water Strong vs Weak acids bases strong electrolytes completely dissociates in water weak electrolytes partially ionizes via reversible process Strong Acids monoprotic donate 1 H HNO3 HCl HClO3 HClO4 HBr HI diprotic donate 2 H H2SO4 hydroxides with Group IA and lower Group IIA starting with Ca Strong Bases Acid Base Rxns Acid Base Salt Water Gas Redox Rxns OIL RIG electrons oxidation is losing reduction is gaining reductants are oxidized oxidants are reduced Oxidation Number ON the number of charges an atom would have if the shared electrons were completely held by the bonded atom which attracts the electrons most strongly elemental form and diatomics 0 sum of ON s for a neutral compound 0 ON of a monatomic ion is its charge sum of ON s in a polyatomic ion must add up to the total charge appropriate sides O 2 unless peroxide 1 Halogens F Cl Br I etc 1 unless covalently bonded H 1 unless hydride 1 Balancing Redox Eq w Half Reaction Method 1 assign ON to the given reaction skeleton 2 separate skeleton into two half reactions oxidation reduction adding electrons to 3 balance atoms via coef cients 4 balance oxygen with H2O 5 balance H with H 6 if in basic add same number of OH as H to both sides forming water with H 7 balance electrons multiply half equation by coef cient 8 combine simplify and cancel out water and H OH Gases Barometer measures atmospheric pressure manometer closed measures gas pressure with no atmospheric pressure involved open measures gas pressure relative to atmospheric pressure Pressure Pascal Force N Area m2 1atm 760 mm Hg 760 torr 101325 Pa 1 mol gas at STP 22 4 L Ideal Gas Law gases behave ideally at high temperatures and low pressures pV nRT pV mRT M density m V pM RT n grams m molar mass M R at STP 0 08206 L atm mol K 62 3656 L torr mm Hg mol K Boyle s Law pressure is inversely proportional to volume pV k p1V1 p2V2 Charles s Law temperature is directly proportional to volume V T k V1 T1 V2 T2 Gay Lussac s Law pressure is directly proportional to temperature P T k P1 T1 P2 T2 Combined Gas Law P1V1 T1 P2V2 T2 Avogadro s Law moles are directly proportional to volume V1 n1 V2 n2 Dalton s Law of Partial Pressures Ptotal Pa Pb Pc Ptotal ntotal RT V Mole Fraction X X percent of gas Xa na ntotal Kinetic Molecular Theory 1 Gases consist of several molecules in constant motion 2 Compared to the total volume of the gas the volume of the sum of the gas particles 3 Attractive and repulsive forces intermolecular forces are negligible 4 Although energy can be transferred between molecules in collisions the average kinetic energy doesn t change with constant temperature perfectly elastic collisions 5 The average kinetic energy is directly proportional to the temperature in Kelvin At a given temperature all gases will have the same kinetic energy is negligible Kinetic Energy EK 3 2RT R at STP 8 314 J mol K J kg m2 s 2 Average Kinetic Energy per Molecule EK molecule 3 2kbT kb Boltzmann Constant 1 381 x 10 23 mu2 2 u velocity at higher temperatures urms increases and the range of velocities of gas root mean square velocity urms 3RT M 1 2 M is molar mass in kg molecules increases distribution widens Graham s Law of Effusion the rate of effusion is inversely proportional to the square root of its molar mass effusion the escape of a gas through a tiny ori ce into an evacuated space ua ub Mb Ma 1 2 van der Waals Equation for non ideal conditions where there exists a nite molecular volume and attractive forces between separate vapor particles p n2a V2 V nb nRT a and b are correction factors speci c to gas Thermodynamics the branch of science that studies the energy ow and transformations associated with physical and chemical change Thermochemistry the area of chemistry that studies the exchange of heat between a system and its surroundings System Surroundings open system can freely exchange energy and matter with its surroundings closed system can exchange energy with its surroundings but not matter isolated system does not interact with its surroundings nothing is exchanged First Law of Thermodynamics Law of Conservation of Energy heat lost by a system is equal to the heat gained by its surroundings