General Chemistry MCAT StudyGuide
General Chemistry MCAT StudyGuide MCAT
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Date Created: 12/03/14
O E Note s subshells are Third Quantum llumber O OOO O A B C E Designates the Each subshell has Egtltln l Egtlt2n2 Egtlt3n3 Fourth Quantum Number O O O A Designates the B ms can have values of can hold up to Pauli Exclusion Principle no occupy the same C If Any different E E Paired Parallel spins Calculations A The number of O O O and p subshells are of a given V ofthe electron in a given Ol they have the same of a given with magnetic quantum numbers from electrons but in the same atom can have the same and thus must have within an atom is equal to of a given to of a given B in each orbital so total is equal to C Number Character Symbol Value St 39239 1 2nd subsheli from zero to n l 3rl Q l i393l Hz 39T 3lV l l Tllquotiil 7 4th spin in 2 or quot5 Eleisenberg Uncertainty Principle A The dual nature of matter says that there is an in the ofthe O O O O O ofa particle and its B That is the more we know about it39s Aufbau Principle A With each new is more stable a B C Electrons are attracted to the nucleus 9 a Because a added to create a and this is on the order of the less we know about it39s anew hasto is added as well will add to the in the them 9 requires the transfer of the system 9 the the electrons the is needed 9 the of the system moves from to as the moves Electron Configuration o A List the and in order from lowest to highest and add a to show the number of in each o B have orbitals and thus with and may occupy either or just remember that don39t always follow the given rules o C An can momentarily and jump to a level creating an atom in an Elundls Rule O A Electrons will not ll up and the Plancllt s Quantum Theory A Electromagnetic energy is O have in the until all in that contain 10 o Remember I I In a PVRT n graph the numerator is the product ofvolume and pressure I 2 Thus the deviations will be less or greater than ideal at some points to either Vreal gt Videal or Preal lt Pideal I 3 Positive deviation molecular very Z and Z I 4 Negative deviation molecular very and moderately Z Chemical Kinetics o A De nition study ofZ and Z o B Equilibrium I I Kinetics deals with the Z as it moves Z equilibriumthermodynamics deals with the Z Zequilibrium I 2 Kinetics deals with Z thermodynamics deals with Z Collision Theory Collision Model o A Reacting molecules must Z but not Zresults in a reaction o B Two requirements I I Z Z due to Z only that is Zfrom another molecule Zofa collision I 2 Z molecules Z Collision Theory Arrhenius Equation o A is often written as Z o B Z Z o C p o fraction of collisions having Z o D e39EquotRT fraction of collisions having Z where Z Z o E k Z dependent on I 2 I 3 or of thus the Zincreases with o F diagram Reaction Rate Equations o A Rate ofa reaction says how quickly Z or Zis changing o B Given in Z o C Factors affecting reaction rates Reaction mechanisms o A how the molecules Z Reaction order o A Reaction order sum of all Z ofthe concentration variables in the rate law o B Reaction order in A the Z of A Reaction rates o A Depends on multiple factors Rate constant o A The Z in the rate law is the rate constant o B The rate constant is an empirically determined value that changes with different reactions and reaction conditions o C Within a given equation I Independent of a Z b I 2 Dependent on a Z b Rate law o A The equation that describes the rate the product of reactants raised to some Equilibrium constant 10 13 o D diagram o E Halflife and o F Pseudo rst order kinetics rst order reaction means only New theory suggests a the rst one but the reaction still Reaction Orders Irreversible Second Order with a Single Reactant o A 9 rate o B Plot results in a straight line with slope o C diagram o D Half life and the ie each is Reaction Orders Irreversible Second Order with Two Reactants o A 9 rate o B Different graph different slope o C Halflife Reaction Orders Irreversible Third Order with a Single Reactant o A9rate o B Plot jresults in a straight line with slope o C Diagram Reaction Orders Graph Comparisons o A Reaction Order rreversibequot o A Initial Rates a technique employed to avoid complications with in the initial moments ofa reaction starting with all and the rate ofthe reverse reaction is Reversible Reactions Rate Determining Step o A Rate determining step lfa complex reaction is separated into elementary steps the rate of determines the rate of the o B Ifthe is the rst step the can be derived directly from and o C Ifthe is other than the rst step the is still the rate determining step steps prior to the slow step o D Steps after the slow step Reversible Reaction Rates First Step RateDetermining Example o I llO2g IlO2g 9 IlO3g IlOg slow step o 2 IlO3g COg 9 IlO2g CO2g fast step o 3 Rate Reversible Reaction Rates Second Step RateDetermining Example o I 2llOg Br2g 9 llOBr2fast step o 2 llOBr2g llOg 9 2llOBrg slow step o 3 Rate o 4 IlOBr2 depends upon if we assume it reaches very quickly IlOBr2 can be written in terms of for step I llOBr2 o 5 Rate o 6 Or we can use Reversible Reaction Rates Equilibrium Approximation o A Equilibrium approximation assumes all steps prior to the rate limiting step o B It requires that the be than the o C Example I I Since the rst step is considered to be set the forward reaction rate equal to the reverse reaction rate and then solve for IlOBr2 I 2 llOBr2 Z 39 3 Rate law rate I 4 o D Ifthere is not a step that is than the others use Reversible Reaction Rates Steady State Approximation o A Steady State Approximation the concentration ofthe is considered to be and it leads to the same result as Catalysis 13 15 o A Chemical equilibrium the condition where the equals the it is the point of o B No change in or Equilibrium Equilibrium Constant K o A Equilibrium Constant KZ o B Equilibrium constant for the Z is the Z ofthe Z o C Equilibrium constant for a Zis equal to Z ofthe for Z of o D Since the rate constant k depends Z so does Z o E K has no because are for a called Equilibrium Equilibrium Constant K Example o A 0A bB 9 cC dD elementary reaction o B RatefOWd Z o C Ratemme Z remember Z o D For only set the two rates equal to each other I I Z o E K this relationship only holds true Equilibrium Equilibrium Constant K and the Law of Mass Action o A Law of Mass action K CCDquotAquotBb o B The Law of Mass Action is good for including NOTE regardless Z ie Z o C Although and including which are considered to be on the MCAT are present and necessary for exist they are given values of in the equilibrium expression and thus Partial Pressure Equilibrium Constant The Principle for Detailed Balance o A Principle for Detailed Balance at equilibrium for reactions with Z the forward and reverse reactions rates Z o B Also any Z resulting in the Zfrom Z must have the Zfor Partial Pressure Equilibrium Constant Equilibrium of Gases o A Reactions with gases Z is written in terms ofZ o B However both constants can be used in the same equation it will just result in different values of K o C NOTE the Z and the Z do not have the same value but are related by the equation I Kp Z 39 3 n Z equation next bullet I 4 Visualized Reaction Quotient Z o A Describes reactions Z o B Q o C Q is not Z it can have any Z o D Since reactions always move Z Q always Z Reaction Quotient Q Predictions o A Q K Z o B Q gt K Z thus it will shift towards Z called a Z o C Q lt K Z thus it will shift towards Z called a Z Le Chateier s Principle o A When a system Z is stressed it will shift in Z Z said stress o B 3 stresses that obey Frenchie I I a Unless you have a reactant and products Then increasing will not shift the Exam Kracllters problem 287 15 18 I REVIEW o Enthalpy H I PV I B At constant pressure Z Z I C AH q at I I I 2 Z at Z I 3 Z o Entropy Extensive I A Increases with I 2 Z I 3 I B lfa reaction increases the of for the reaction Z not necessarily the Z or Z I C Greater Z greater Z o Gibbs Free Energy Equations I A AG AH TAS I I Every variable above refers to the Z and not the Z I 2 Only good for constant Z reactions I B AG O at I I I 2 Z I 3 Z I C AG positive I I The smaller the Z for the reaction with the positive AG I D AG negative I I I 2 Z only if o a Z o b Z o Internal Energy Definition I A Internal Energy the Z energy of molecules on a Z I I I 2 Z I 3 Z I 4 Z I 5 Z I 6 I B Internal energy does not include Z that is it is all possible forms of energy on the Z I C A Zat Z with no Z or Z elds can only have energy change from I D First law of thermodynamics rewritten I E Reaction in such a system with no change in there is no and I F Note for an internal energy only depends on o Work PV Work I A Constant pressure times the change in volume I B Occurs in a Z no Z no Z I C Work is a Z I D PV work takes place when a gas Z against a Z regardless of whether or not the Z is Z I First Law of Thermodynamics o A De nition energy ofa Z and Z is Z 18 o C AG negative 25 I I Increase I 2 Gibbs Free Energy Spontaneity Remember o A Enthalpy j o B Entropy AH AS AG Spontaneity Negative Positive Negative Negative Positive Positive Positive Negative 75 28 Name Formula Nitrite 3 Nitrate 3 Sul te 3 Sulfate 3 Hypochlorite 3 Chlorite 3 Chlorate 3 Perchlorate 3 Carbonate 3 Bicarbonate 3 Phosphate 3 Names You Need to Know 2 Name Formula NO239 3 N03 3 S032 SO42 CO39 j CO239 CO339 CO439 3 C032 j HCO339 PO43 Units of Concentration O O O l Molarity 2 Molality l 3 3 Mole fraction l 78 lo s 391I39 39lm39c vapor Solution g L l uu liquid K K V l s o B When added to a some will reach the ofthe solution and the amount of area available for the molecules o C That is these fuckers use up prime real estate but into the o Less prime real estate molecules while the l ofthe and 2 stay the same so o E From we know that if decreases at and then has to proportionally and it does by o F Paoult s Law I I quot Pv 39 Z Xa I 0 f Pa Vapor Pressure Volatile Solutes in o A Volatile Solute A solute that vapor pressure o B Like it will compete for the the prime real estatequot o C Unlike ofthe molecules escape from the surface and to the o lfthe solution is solvent and solute can be used to nd the of both the and the o E Paoult s law I I quot Pv 39 2 Paxa 30 But wait bitches lt doesn39t stop here What it the solution isn39t Vapor Pressure Volatile Solutes in between molecules be changed o I lfthe solution is the o 2 Whereas with and solutes in ideal solutions it was a simple the added solute shit takes up space and or it 5 here the added solutes alter the of the themselves Aw shit o 3 Why aw shit Because this means either or will be needed by the to into the causing from what predicted Vapor Pressure Paoult s Law Recap o l llonvolatile Solutes ldeal Solutions f97 ofthe is then the vapor pressure will be 97 ofthe vapor pressure ofthe o 2 Volatile Solutes ldeal Solutions lf97 ofthe is then vapor pressure will be 97 ofthe vapor pressure ofthe 3 ofthe vapor pressure ofthe o 3 llonideal Solutions I l Negative Heat of Solution a bonds are formed b bonds are able to from the cotthefrom I 2 Positive Pleat of Solution a bonds are formed b bonds are able to from the 30 32 o D X moles per liter of BaF2dissolve then there are Z moles ofZ and Z moles of o E Plug in I l 24 x IO395 ZZ2 I 2 24 X lO395 4x3 I 3 X l8 x lO392 solubility of BaF2 in of at Solubility Product Constant Example Continued o A Okay but what ifwe dissolve l mole of llaF It would completely dissociate o B Spectator ions lla Zthat have on o C Common ion effect when Z that may or may not be from the Z Z cause an Z in accordance with Z Z but does not affect Z I I F ions Z affect equilibrium I 2 By Z Z the reaction will Z in the Z that Z the Z Z which is the Z I 4 This Z the Z ofZ I 5 24 x lO395 ZZ2 I 6 Because the Zis Z to the Z X and even Z is going to be much I 7 Z the Z and solve for just X2 I 8gtlt24gtltlO395 Solubility Guidelines o A Insoluble compound with Z ofZ than Z o B Ionic compounds are Zthat contain I I Z Z I 2 Z Z 39 3 Z 39 4 o C lonic Compounds are Z that contain I I Z Z and Z compounds Z o D Sulfate Compounds Z are Z but are Z ifthey contain I lZZandtheZZ o F The heavier alkaline metals Z are Zwhen they contain 39 l I 2 Z Z o G Generally Z compounds except for the cases mentioned above are NOT THE HEAVIER ALKALINES I l and Z Z Solubility Factors o I Solubility is affected by I A Z I B o 2 The solubility ofZ and Z are not affected by the above factors o 3 Gases in an Z Z solution an Z in pressure ofZ a over a Z is Z proportional to the Z of gas a ifthe Z does not Z with or Z in theZ This is given by Z Solubility Factors Henry39s Law o A Equation I Z Z I I C Z i Z I 2 kg Z Z I 3 PV Z Z Z ofgas a Z the solution o B Equation 2 Z Z I xa Z I 2 P Z I 3 kg Z o C Henry39s Law constant I I ls Z from equation I to equation 2 37 34 Heat Capacity Phase Change and Colligative Properties 34 36 lleat Capacity Water o A Water speci c heat capacity o B The old de nition ofa calories new is Calorimeters o A Calorimeter device that measures change o B Two types I I Constant coffee cup I 2 Constant bomb Calorimeters Constant Pressure o A Used to measure o B Reaction takes place with open top at atmospheric pressure thus expanding gases cannot be contained constant pressure o C Recall at constant pressure q o Thus from q MCAT q change in Calorimeter Constant Volume o A Used to measure the change in ofa o B Recall at constant volume q o C The steel vessel heats up the water around it o Thus from q MCAT q Rhase Change Water Example o A Water at constant pressure of l atm I I l 0 C and add heat molecules and temperature I 2 0 C temperature rising with additional heat because bonds are and ice is I 3 O C temperature rising with additional heat as molecules I 4 lOO C temperature rising with additional heat because bonds are and water is I 5 lOO C temperature rising with additional heat as molecules o B iagram I I I211 1l E R Sn I E 3 hII A 3 6 5 139 P 39 D E w 1 9 a 1 T E jil 1 IIl39LI Rhase Changes Normal lvleltingBoiling Point o A Normal melting point at the heat capacity is o B llormal boiling points at the heat capacity is o C llormal I I Indicates pressure I 2 Constant pressure q 36 38 pressL1re a tm O F iagram IIIIIII7quotquot39l1I39iIquot I Phase Diagrams Water vs Carbon dioxide 0 A I atm can be determined without labels I I Water at I atm exists in all three phases at different temperatures thus the I atm line must be the triple point I 2 Carbon dioxide at I atm sublimes thus the I atm line must be the triple point 0 B Compare the equilibrium lines separating the liquid and solid phases I I Water ice oats I a Why Increasing decreasing thus water density gt water density I 2 Carbon dioxide positive slope o C Check this shit out I Colligative Properties 0 A Colligative properties Depend solely on the of particles regardless ofthe of particle o B Four colligative properties of solutions I T T I 4 T T I Colligative Properties Boiling Point Elevation for IIonvoIatiIe Solutes o A From adding nonvolatile solute vapor pressure and we know when vapor pressure equals thus addition ofa solute the boiling point need heat addition to boil o B Equation for an I I AT I H ltb T I 3m notor I 4 i of particles which a will when added to solution 0 C vanlt IIoff factor I I Expected value I a taIlte ion pairing into account I 2 Observed value I a taIlte ion pairing into account I 3 Ion Pairing I a Ideally dilute solution of upon complete eg IIaCI IlgCI2 I b IIonideaI solutions not due to the solute but rather of or into a caused by I Colligative Properties Boiling Point Elevation for Volatile Solutes o A Boiling point elevation can be applied to nonvolatile solutes volatile solutes o B Why Because volatile solutes can or vapor pressure and thus or boiling point respectively which obviously isn39t a fucking eIevationquot RR 40 a Pure water is not itself targetedquot for osmosis because it is completely dilute why would solvents move against their gradients to dilutequot it further I b Since free energy is in part a measurement of entropy something that is completely dilute has zero potential entropyquot ie there is no chance some solvent is going to dilute it cause dissolution and increase entropy I 2 Pure water assigned an osmotic potential value of I 3 Solute added osmotic potential becomes a Solution now has potentialquot to be diluted in an entropy driven manner I 4 At and 0g a and means is the only force at work I 5 water ows from osmotic potential to osmotic potential a is increased o F Water Potential I I l etinition The potential ofwater molecules to move from a solution more water less solute to a solution less water more solutes the same as I 2 ls a function of a does not have to be b does not have to be c I 3 moves from water potential to water potential when two are separated by a membrane permeable to but not I 4 iagram explanation when at points A pure water and B solution have the same but point B has lessquot more negative than point A I 5 iagram ll iIRT O Q quot 1Hl it p 1 quotquotquotquotiquot 39 H ll Il l 07p quot39lkI i39 Ii p f p T T T T T A T gt 3 quot quot vll39lI l llli ln iamiii ii llu i uI39 39 H1 ltu tIi39 lIl39llll ate Time Score of X39s 54l3 3793 7 58 l 3 2 l 204 4 40 o C Only for I Definitions BronstedLowry 43 o A Bronsted Acid anything that that a proton o B Bronsted Base anything that Z a proton Definitions Lewis o A Lewis acid anything that Z a pair ofZ o B Lewis base anything that Z a pair ofZ o C Lewis acids include I I I a Z I b Z I 2 All except a b C I I 3 Every ZZ o D Lewis acid strength I I Strong Z cation Z charge less Z wants an Z more I 2 Weak Z cation Z charge o E Note Lewis acids are not necessarily all Z or Z acids pH o A Measure ofZ ion concentration o B pX is a function of any X pX Z X o C Measuring Z ion concentration in Z per Z Z 39 l PH Z Z pH Concentrations o A Usually Z Z any H is possible though o B 25 C pH I I 7 Z I 2 gt7 Z I 3 lt7 Z o C pH change ofZ is a Z fold increase in Z pH Estimations o A Example I I I I0 3l6 I 2 X I 3 Why I00 Z and IO39 Z so X must be between Z and Z I 4 X 05 o B Example 2 I H 103 I 2 Z I 3 3 I 4 Thus Z 3 o C Example 3 I I Little more than lO393 say 4 X lO393 I 2 Solution must be a little Z acidic pH Z I 3 llotice4X lO393lt lO392 so 3 gt Zgt 2 pH Conjugates o A HA H20 9 A I I3O o B Conjugate acid when the Z Z Z a proton o C Conjugate base when the Z Z Z a proton pH Conjugate Strengths o A Stronger acid Z conjugate base o B Stronger base Z conjugate acid o C WARNING this does not mean that Z acids have Z conjugate base it may be or o D Check this motherfucking diagram 43 45 I c Impact of this increasing j by lOx result in lOx j the acid increases but the percent dissociation decreases I Percent Ionization of an Acid o A Factors affecting percent ionization of an acid I I of solution I 2 of acid I 3 of acid I Molecular Structure and Acid Strength Halides o A Three factors determine if a compound will release its proton and I I Strength ofthe bond holding the hydrogen to the molecule I a HE is the most good but also the bad I 2 Polarity ofthe bond I a HCl is while CH methane I 3 Stability of the conjugate base I a HF is the most good but F is the bad and thus the most j bad I 4 Diagram I Molecular Structure and Acid Strength Oxyacids o A Polarity electronegative oxygens polarity o B Stability the multiple oxygens can the bonds o C Oxidation number of central atom acidity proportionally with the oxidation number ofthe central atom o D Diagram I Hydrides o A Binary compounds contain only elements and ifthey have hydrogen are called o B Hydrides can be or I I Basic I a on the periodic table eg I b hydrides I 2 Acidic I a on the periodic table eg I b hydrides I 3 Neutral I a hydrides I b hydrides o C Metal Hydrides or o D Nonmetal hydrides or j with the exception of which I39m guessing is basic o E Acidity of hydrides I I going down the period table I 2 H2O HZS H2Se H2Te I 2 going across the periodic table I 3 Maximum acidity bottom right I Hydrides Diagram o A I Equilibrium Constants for Acid Base Reactions o A Pure water reacts with itself to form and I a H2OH2O9j o B This is called I Equilibrium Constants Water o a Water o b lltWwater o c Ka water o d pKa water I Equilibrium Constants for Acid Base Reactions Autoionization 45 47 b molL of CN39 ions I Al Undissociated HCN 5 Plug all this shit into equation from step I a 62x lOquot0 I 6 Solving for requires a quadratic formula fuck that noise We make the assumption that lt of 00l I 7 After throwing out a 62x lOquot0 825gtlt IOquot ltpH lt Finding the pll Weallt Base Example o A Same exact steps just nd and that from Salts o A Salts compounds that in water o B Upon dissociation create or conditions o C pH predicted by comparing the ofthe respective Salts Example o A Na and Cl are the of and respectively o B Thus NaCl dissociates solution Salts Example 2 o A llH4llO3 composed of ofthe base and the weallt ofthe strong acid V respectively o B llH4 o C N03 o Thus llH4llO Salts Weak lewis Acids o A Remember All act as Lewis acids in solutions except I a I b Titrations o A Titration drop by drop mixing of an and a o B Purpose nd by comparing to o C ApH of as or added curve Titrations Strong Acid and Strong Base PH l o A o B Portion ofthe graph that most closely represents a line the ofthis line is called the or the Titrations Equivalence PointStoichiometric Point o A efinition ofthe line that is most closely o B For a monoprotic acid it is the point in the when there are equal of and in solution o C Example of Equally strong acid base titrations llCl and lla ll Graph above I l to correspondence I 2 Equivalence point number of of exist in solution I 3 Note this does mean equal the may differ and thus will too 47 49 I I Ka j I Ka I 3 Log rule logllta I u plta o B Equivalence point I I Kb I 2 Equilibrium expression Kb I 3 OH I 4 logOH39 I 5 j 0Z I Titrations Butters o A Butter the spot in a speci cally the where the amount of or can be added with the change in o B To make a buffer I I Choose an with a closest to desired of buffer solution I 2 Mix amounts ofthat and its conjugate I 3 Goal gtgtgt or o C Summary tons ofa and its pn quotquot i i Bu vr pil1t 39 l l IIpvrinwnt held I in lhis pll rn1ltv I In lvullvrml sulnlinn o Fl iagram L I Indicator o A Chemical used to nd the o 3 Usually a whose is a different color o C Human eye detection 2 llO o Titrate acid with base I I Low pH form predominates I 2 pH rises form arises I 3 Higher pH becomes visible o E Titrate base with acid I l o E Summary pH of color change depends upon of I Indicators Range o A Range pH values ofthe two points of color range predicts I j o B Lower range of color change I l pH 9 pH o C Upper range of color change I I pH 9 pH I Indicators Endpoint o A Point where the changes o B Endpoint is not the o C lndicators usually have a that covers the whole I Indicators Endpoint and Henderson Hasselbalch o A Question If HH be used to nd the at the why can it be used to nd the that will include the 49 51 Electrochemistry E1 52 Equation Review Free Energy and Chemical Energy Equation Review o A Cell Potential Free energy I I AG o B Standard State Equation I I AG o C Nonstandard State Equation I I AG I 2 AG o D Equilibrium AG O I AG or AG a Varies with temperature o L o 2 I 3 Relationship ltand AG llfltthenAG jO 2 If ltgt thenAG jO 3 If ltlt thenAG jO I 4 Fucking Warning I I If K gt I does NOT mean the reaction is spontaneous 2 If K gt I DOES mean the reaction is spontaneous at conditions and the specified o E Nernst Equation I I E I 2 E E7 54 o A Find the molarity of a reducing agent titrate it with aZZagent o B Example Find molarity of Sn ions I I Titrate with known concentration of Z Zagent Ce4 I 2 Sn ions to Sn4 ions Ce4Z to Ce3 I 3 Analyze Z electrons to Z Ce4 but Z electrons to Z Sn2 I 4 Summary moles Ce4to reach equivalent point Zx moles Sn2 in solution Potentials o A Electric potential E electric potentials are associated with Z Zbecause Z are transferred and Z have charge Potentials SHE o A Z Z SH E used to separate the Z ofa reaction into Z and Z components called Z Z Potentials Half reaction o A Z a component ofa Z Z o B Every half reaction must be Z by Z o C Half reactions are usually listed as Z Z with Z Z just being the opposite o D Half reactions at Z C to memorize I l Strongest oxidizing agent Z I 2 Strongest reducing agent Z Half Reaction Potential E a Second half of bottom reaction nal reaction ofZ Z Potentials Electric Potential o A Electric potential has no Z Z but rather Z assignments based on the Z value ofthe half reaction at Z I l2H2e399H2 I 2 E 000V R4 56 I a H20 l2 50Cl39 9 2l0339 2H 5Cl39 I Balancing Redox Reactions Basic Example 0 O O O O I Mn0439 Br 9 Mn02 Br0339 2 3equot 4H Mn0439 9 Mn02 ZH20 I a Balance Manganese atoms NA I b Balance Oxygen atoms 2 I c Balance Hydrogen atoms 4 I d Count charges I I Left side 3 charge 4 I I 2 Right side 0 charge 0 O I e Balance charges 3 electrons left side malltes both sides 0 charge 3 3H20 Br 9 Br0339 6H 6equot I a Balance bromine atoms llA I b Balance Oxygen atoms 3 I c Balance Hydrogen atoms 6 I d Count charges I I Left side I charge I I 2 Right side 5 charge I 6 I e Balance charges 6 electrons right side malltes both sides I charge 4 Balance the electrons for both equations I a Electrons must be on opposite sides Equation I has 3 electrons on the left side whereas Equation 2 has 6 electrons on the right side I b Balance electrons Multiply entire Equation I by 2 I I 3e39 4HMn04399Mn022H20 X2 I 2 6equot 8H 2Mn0439 9 2Mn02 4H20 5 Add the equations together a 6e 8H 2Mn0439 3H2O Br 9 2Mn02 4H2O Br0339 6H 6e 6 Cancel extra shit I a Examine the equation I 6e 8H 2Mn0439 3H2O Br 9 2Mn02 4H2O Br0339 6H 6e I b Fuck you electrons I 8H 2Mn0439 3H2O Brquot 9 2Mn02 4H2O Br0339 6H I a Fight to the death Hydrogen ions I I 2H 2Mn0439 3H20 Br 9 2Mn02 4H20 Br0339 I a You too water molecules I I 2H 2Mn0439 Br 9 2Mn02 H20 Br0339 7 Basic Solution Neutralize Hydrogen ions with Hydroxides I a 20H 2H 2Mn0439 Br 9 2Mn02 H20 Br0339 20Hquot I I Left side 2 hydrogen ions get whacked by 2 hydroxide ions I 2 Whatever goes on one side must go on the other 2 hydroxide ions to the right side I 3 These combine to form water molecules 8 Balance the Water Molecules I a Examine the equation ZH20 2Mn0439 Br 9 2Mn02 H20 Br0339 I b Water molecules FIGHT H20 2Mn0439 Brquot 9 2Mn02 20H Br0339 9 Check this shit out I a H20 2Mn0439 Br 9 2Mn02 20H Br0339 I GalvanicVoltaic Cell 0 A Preface I I Two electrically conducting are placed in contact I 2 One from one cannot freely flow to the other I 3 Result j difference between the 9 creates E6 58 0ob RCLI n c Cat O 39 39 ll AlgCl CI I Pt Z 3 nu V iIlIIIH1 A I I gt ZI I liq 239 gCIlt v gt Agvs I CI my Galvanic Cell O 7f iagram with 39sIdIIIdl39I Iiydrugcn LIcclmdc ISIIF o C Note I I Oxidation potential of hydrogen is I 2 the of any used in conjunction with of the occurring at the other I 3 Thus half reaction can be measured using o Note No in the above cell I I Why Both are in contact with the same M not necessary o E Liquid Junction I I Required when a cell contains two different I 2 can move across the liquid junction thus creates an additional that affects the of the cell I 3 A salt bridge this I Salt Bridge o A Atype of used tothe in a o B Composed of lillte o C Purpose I I Allows between without creating within the How you ask Fuck you I39ll tell you o How I I llt ions move toward the at the that Cl ions move toward the o E And if we don t have one I I mix 9 I 2 path for electrons to move from to 9 I 3 the cell 9 I 4 Cell potential iagram bitches ER 60 o A AG Z Z Note Z Zcan be at any Z just assumed to be at Z K I I If we use only Z Z concentrations for Q I 2 Then Q Z I 3 And RTlnQ Z I 4 Thus Z Z o B AG Z o C At quilibrium I I No available Z Z to do Z so I 2 AG Z I 3 PluginZforAGinZZ I 4 AG I 5 Rewritten Free Energy and Chemical Energy Equilibrium Equation o A AG Z I l aries with temperature 0 anj b o B Relationship Kand AG I llfKlthenAG Z I 2f Kgt lthenAG ltZ I 3lf Klt lthenAG gtZ o C Fucking Warning I I If K gt I does NOT mean the reaction is Z I 2 If K gt I DOES mean the reaction is at conditions and the Free Energy and Chemical Energy When Concentrations Change How Do We Find the Potential God Damn Z o A Take the equation AG AG RTlnQ o B Substitute Zfor AG o C And Substitute Zfor AG o D Divide by Z o E Equals Z Z Nernst Equation Free Energy and Chemical Energy Nernst Equation o A o B Base IO logarithm Z o C Purpose I I Plug in Z Zto create 3 I 2 Allows us to nd the Z Z Galvanic vs Electrolytic o A PotentialSpontaneity I l Galvanic and thus by AG nFEmaX I 2 Electrolytic and thus by an outside source by AG nFEmaX Concentration Cells o A Concentration Cell I I Limited form ofa Z Z I 2 Contains a Z Z Ztallting place in one half cell I 3 Z Z Ztallting place in the other half cell I 4 Never at Z Z conditions thus I 5 Always requires the Z Zto solve for the Z Z o B Half Reactions I I Adding the two half reactions Z Z I 2 Must use the Z Zto nd the Z o C Entropy I I Nature wants greatest Z 60 61 I 2 Thus the concentrated side will try to become concentrated ow accordingly o D Potential I l Concentration cellstend to have potential Concentration Cell o A Diagram i m11i1l quot l llfl V i FLquot 2 It 39l il la lw Concentration Cell o B llernst Equation for potential at 250C I I Eezl both a and I 2 Substitute for the Fe rations on either side I 3 Result for the case above E E 0062og00O a n 2 because electrons are used the reaction occurs b E Electrolytic Cell o A Electrolytic cell I I Hook up a across the ofa and the cell to run o B Potential o CTerminals I l Anode a Marked b astill occurs here I 2 Cathode a Marked b still occurs here I 3 Why a Galvanic cells are used to an I b Thus the are labeled so that the negative will ow the o D iagram 61 C Form l cations D VERY reactive E React with nonmetals to form ionic compounds F React with hydrogen to form hydrides Alkaline Earth Metals Group 2A A Second family B Hard higher density and melting point than alkali metals C Form 2 cations D Less reactive than alkali metals o E Within the family reactivity heavier gt lighter Group 4A Carbon and Shit o A Form 4 covalent bonds with nonmetals o B Only carbon malltes triple bonds within this family Group SA Nitrogen and Shit o A Form 3 covalent bonds o B Except for Nitrogen all can form 5 covalent bonds d orbitals o C With a Lewis base can make 6 bonds Chalcogens Group 6A o A Oxygen reacts with metals to form oxides ie BaO o B Oxygen reacts with alkali metals to form peroxides ie lla2O2 and super oxides ie KO2 Halogens Group 7A o A Seventh family my own interpretation o B Most are diatomic o C Like to gain electrons o D All react with hydrogen to form gaseous halides NobleRareInert Gases o A Eighth Family my own interpretation o B llonreactive o C All gases at room temperature o D Unlillte all other elements they have endothermic electron af nity values MainGroupRepresentative Elements o A Section A metals Transition Metals o A Section B metals o B When forming ions lose electrons from s subshell rst and then d subshell and thus can form multiple ions eg Vanadium V o C Form colored solutions a result of partially lled d orbitals these electrons can absorb photons and be bumped up to a higher energy orbital Diatomics A Oxygen B llydrogen C Nitrogen D Halogens E Heat of Formation I The rst three and uorine from the Halogens all have an enthalpy change of zero OOOO OOOO O OOOO Small atoms o A Tend to be more reactive because they can39t stabilize charge Cations o A Tend to be smaller Anions o A Tend to be larger lsoelectric ions o A Same number of ions different protons o B Get smaller with increasing atomic number more protons to pull in electrons o A Two or more elements in whole number ratios Molecules o A The repeating groups of atoms in compounds o B lonic compounds do not have molecules Empirical formula o A Simplest whole number ratio of atoms in a compound Molecular Formula o A Representative of all the elemental atoms in a molecule Ionic compounds o A Named after their cation or anion eg Copper ll ion o B Monatomic anions ide eg Hydroxide o C Polyatomic ions ite or ate eg N02 nitrite and N03 nitrate Molecular Compounds o A Two nonmetals o B Always has covalent bonds Acids o A lfname ends in ide it starts with hydro and ends in ic eg Hydrosulfuric acid o B If an oxyacid more ogtltygens ic and less oxygens ous Binary molecular compounds o A Compounds with only two elements o B Name begins with element farthest left and down may get pre x o C Second element gets the ide o D Ex Dinitrogen Tetrogtltide N204 Physical Reaction o A Maintains the molecular structure o B Ex melting evaporation dissolution rotation of light Chemical Reaction o A Molecular structure changes o B Ex Combustion metathesis redogtlt Run to completion o A Moves to the right until the supply of at least one reactant is gone o B Reactions often don39t do this because they reach equilibrium rst Limiting Reagent o A Runs out and fucks everybody o B Ex alcohol on spring break Theoretical Yield o A The amount of product produced when a reaction runs to completion Actual Yield o A The actual amount of product collected Percent Yield o A Actualtheoretical gtlt lOO percent Reaction types o A Combination A B 9 C o B Decomposition C 9 A B o C Single Displacement A BC 9 B AC o D Double DisplacementMetathesis AB CD 9 AD CB Bonding in solids Crystalline o A Sharp melting point o B Characteristic shape with repeating units o C Classi ed I I lonic electrostatic forces eg salts I 2 Network covalent in nite network of covalent crystals eg diamond I 3 Metallic metal atoms bound together by delocalized electrons eg any metal I 4 Molecular individual atoms held by intermolecular bonds eg ice Bonding in solids Amorphous o A No characteristic shape or melting point has a melting range not point eg glass Polymers o A The dual nature wave particle of matter says that there is an inherent uncertainty in the product ofthe position ofa particle and its momentum and this uncertainty is on the order of Planck39s constant AxAp3h o B That is the more we know about it39s position the less we know about it39s momentum Aufbau Principle o A With each new proton added to create a new element a new electron is added as well o B Because a lower energy system is more stable a new electron will add to the lowest energy orbital in the lowest subshell o C Electrons are attracted to the nucleus 9 a force has to separate them 9 requires the transfer of energy into the system 9 the farther away the electrons the less energy is needed 9 the energy of the system moves from negative to zero as the electron moves in nitely far away Electron Configuration o A List the shells and subshells in order from lowest to highest energy level and add a subscript to show the number of electrons in each subshell o B Transition elements have degenerate orbitals same energy level and thus with 4s and 3d may occupy either or just remember that transition metals don39t always follow the given rules o C An electron can momentarily absorb energy and jump to a higher energy level creating an atom in an excited state Hund s Rule o A Electrons will not ll up any orbital in the same subshell until all orbitals in that subshell contain at least one electron and the unpaired electrons have parallel spins Planck39s Quantum Theory o A Electromagnetic energy is quantized o B Thus photons and electrons have quantized energy level o C When an electron emits a photon it falls an energy rung when it absorbs a photon it goes up an energy rung ifthe photon doesn39t have enough energy E hf the photon is de ected away and electron stays in its current rung o D lfa photon doesn39t have suf cient frequency it will never eject an electron regardless of the number of photons Work Function D o A The minimum amount of energy required to eject an electron o B Kinetic Energy ofthe ejected electron is given by the energy ofthe photon minus the work function KEeemn hf CI CHAPTER 2 Gases Kinetics and Chemical Equilibrium O A lltEaVg 3ZRT B Average translational kinetic energy is found from the root mean square rms velocity square root ofthe average ofthe squares ofthe molecular velocities o C rms velocity slightly gt average speed D The Kinetic Energy is inversely related to the temperature the speed is directly proportional to the square root ofthe kinetic energy I I KE 3ZRT and I 2 V sqrtKE o E Remember this is the average KE ofgas molecule little to no molecules could have this energy they vary widely Ideal Gases Graham39s Law o A Same temperature means different molecules in a mixture have the same average KE but because they have different masses they have different rms velocities o B Setting the two KE equal to each other one can determine the relationship between their rms velocities more speci cally the ratio o C VV2 sqrtm2sqrtm I l Dependent upon a Molecular weight directly proportional to effusion rate b Pressure o D Pressure vs Time graph effusion rate is the slope o E Graham39s Law provides information about two types of gaseous spreading effusion and diffusion Ideal Gases Effusion o A De nition spreading ofa gas from high pressure to very low pressure through a pinhole an opening much smaller than the average distances between the gas molecules o B Molecules with higher rms velocities will effuse faster o C Calculated effusion rateeffusion ratez sqrtm2sqrtm Ideal Gases Diffusion o A De nition the spreading of one gas into another gas or into empty space o B Diffusion rate is much slower than rms velocity because gas molecules collide with each other as they diffuse o C Calculated diffusion ratediffusion ratez sqrtm2sqrtm Real Gases Van der Waals Equation A Predicts how real gases deviate from ideal behavior B Calculated P anV2 nb nRT C b measure ofthe actual volume occupied by a mole of gas D a strength of intermolecular attractions E Values ofa and b usually increase with the molecular mass ofa gas and molecular complexity of a gas Real Gases Deviations o A Volume Real gas molecules do have volume 39 l Vreal gt Videal I 2 Videa is calculated from PV nRT o B Forces Real gas molecules exhibit forces on each other I I Repulsive when very close minor I 2 Attractive when far apart major and are thus pulled toward the center of the container causing them to slow before they hit the wall thinllt harmonic motion lltinda and thus have less pressure Prea lt Pidea I 3 Pidea is calculated from PV nRT Real Gases Facts o A Deviate from ideal behavior when their molecules are close together o B High pressures l 0 atm push gas molecules together o C Low temperatures boiling points cause gas molecules to settle close together Real Gases Deviations Explained Even More o A Deviations 39 l Vreal gt Videal 39 2 Preal lt Pideal O O OOOOO 11 Reaction Rate Equations Example o A aAbB9cCdD o B Lower case letters are stoichiometric coef cients Reaction Rate Equations Types o A Molecularity the number of molecules colliding at one time to make a reaction o B Elementary Reaction occur in a single step only here can the coef cient ofthe balanced equation serve as the exponent in the rate law o C Unimolecular one molecule colliding o D Bimolecular two molecules colliding o E Termolecular three molecules colliding Reaction Rate Equations Intermediates o I Intermediates species that are products of one reaction and reactants of a later reaction in a reaction chain o 2 Concentrations are often very low because they are both unstable and used up quickly Reaction Rate Equations Directions o I Reaction rates are reversible that is as products are formed products begin to react to form reactants Reaction Rate Equations Rate Law o A Rate law considering the forward reaction only BI Rateforward lltfl A lalBlB C k rate constant for the forward reaction D 0L and 5 order of each respective reactant E OL 5 overall order ofthe reaction Rate Law Experimental Determination OOOO Trlal lAlinitial M lBlinitial M rinitial lvlSec l 00 l 00 20 l l 00 200 8 l 2 200 200 I59 3 o A lnfo I l Trial l r lltAXB lltl 00quotl 00 I 2 Trial 2 r2 lltAXB lltl 0Oquot200 o B Divide the second equation by the rst r2r 8l20 lltl O0X200 lltl 00quotl00V 200 I 2 4 200 I 3 y 2 o C Repeat for other trials o D r lltAB2 I I Reaction order with respect to A l I 2 Reaction order with respect to B 2 I 3 Overall reaction order I 2 3 o E Calculate llt substitute the values from any one ofthe above trials into the rate law eg I I 20Msec lltx l00 M x l00lquotl2 I 2 k 20lquotl392secquot o F Thus the rate law r 20lquotl392 secquot AB2 o G Note increasing the concentration of reactants will result in more collisions which will increase the reaction rate Reaction Orders Irreversible Zeroth Order o A Plot A with respect to time t results in a straight line with slope lltf 11 16 o C Q lt K product lt reactant then at equilibrium thus it will shift towards the product side called a rightward shift le Chatelier s Principle o A When a system at equilibrium is stressed it will shift in whatever direction reduces said stress o B 3 stresses that obey Frenchie I l reactant or product a Unless you have a solid reactant and gaseous products Then increasing solid will not shift the equilibrium Egtltam Kracllters problem 287 I 2 APressure I 3 ATemperature a The reaction E forward and reverse is always increased with increased temperature even if the reaction is egtltothermic Egtltam Kracllters problem 289 I Solvation reactions I H Pressure increase due to addition of nonreactive gases Le Chatelier s Principle Haber Process Example o A ll2g 3H2g 9 2llH3g Heat o B productreactant Add N2 shifts to the right to reduce partial pressure of N2 Equilibrium Concentrations Concentrations l q1ililviui11 llti t39 N 4 FLLllllll39lll11t Time Time o C Heat Add heat reaction pushed to the left Equilibrium Concentrations Concentrations Equilibrium Time o Pressure Reduce size of container at constant temperature Pressure increases 4 gas molecules on the left side and 2 on the right so shifts to the right E 8 S Equilibrium Q p J m 2 E 5 E 2 5 J E ejH U K T H U NH 2 a quotquotquot v R ime Time Le Chatelier s Principle Special Exceptions o l Solvation reactions the solubility of salts increases with temperature regardless if its egtltothermic ie ifthe salt is on the left it will dissolve when heat is added even if heat is on the right this is because entropy increases with dissolution and the entropy factor becomes more important as the temperature increases TAS o 2 Pressure increase due to the addition of a nonreactive gas Add He to the Haber system the total pressure will increase but the partial pressures of the other gases will not so no equilibrium shift occurs CHAPTER 3 Thermodynamics 1F 18 I B Occurs in a system at rest no gravitational potential energy no kinetic energy I C Work is a path function I D PV work takes place when a gas expands against a force regardless of whether or not the pressure is constant First Law of Thermodynamics o A De nition energy ofa system and surrounding is always conserved o B Thus any energy change to a system must equal the heat ow into the system plus the work done on the system AE q w I I Note this convention is where work on the system is positive 2 If it were work by the system were positive it39d be AE q w Second Law of Thermodynamics o A Definition Heat cannot be changed into work in a cyclical process o B Definition 2 entropy of an isolated system will never decrease o C Definition 3 239 law generally deals with irreversibility Third Law of Thermodynamics o A Assigns a zero entropy value to any pure substance element or compound at absolute zero and in internal equilibrium o B Entropy change tiny change in heat per Kelvin in a reversible process I I AS dqrevT Zeroth Law of Thermodynamics o A Definition Two systems in thermal equilibrium with a third system are in equilibrium with each other o B That is two bodies in thermal equilibrium share a thermodynamic property which must be a state function its called Temperature Thermodynamics o A Thermodynamics the study of energy and its relationship to macroscopic properties based on probabilities and thus really only work for macroscopic complex systems with a lot of molecules and cannot be applied to the microscopic systems indeed it is the opposite of quantum mechanics Thermodynamics Division of the Universe o A System macroscopic body under study three types I I Open exchange both mass and energy with their surroundings I 2 Closed exchange energy but not mass with their surroundings I 3 Isolatedadiabatic do not exchange energy or mass o B Surroundings everything other than the macroscopic body under study State Functions State Function o A State physical condition ofa system described by a speci c set ofthermodynamic properties o B State Function When a state can be described by 3 properties and is independent of the path of its formation think conservative forces which can also be stated as It can be measured without knowing any of its historyquot I I Note the macroscopic state of any one component uid system in equilibrium can be described by at least 3 properties I must be extensive I 2 lfyou have at least 3 properties all others can be speci ed o E Two Types quack I I Extensive A Definition proportional to the size ofthe system B lfyou combined two identical systems an extensive property would double C Divide one extensive property by another intensive property D Examples o I Volume V o 2 of moles n o 3 Enthalpy o 4 Entropy 1R 20 lleat Radiation o A Definition thermal energy transfer via electromagnetic waves it is the only type of heat that transfers through a vacuum o When metal is hot it goes red 9 yellow 9 white 9 blueit s radiating visible electromagnetic waves o C All objects above OK radiate heat o Power rate of electromagnetic radiation P osAT4 I l A surface area I 2 T temperature in K I 3 8 emissivity ofthe object39s surface value ofO to l I 4 o Stefan Boltzmann constant 567 x lO398 Wm2llt4 a Black body radiator emissivity of I only in theory b Dark colors radiate and absorb more reflect less c light colors re ect more radiate and absorb less o E Emissivity egtltample better to paint your house white reflects more heat in the summer your house is cooler than the environment radiates less heat in winter house is warmer than environment o F Rate at which object absorbs radiant heat from its environment P osATe4 T04 I l To temperature of object I 2 Te temperature of environment o G llewton s Law of Cooling the rate of cooling ofa body is proportional to the temperature difference between it and the environment Work o A efinitioh any transfer of energy that is not heat o B Whereas in physics it39s the change to a motion or position of body in chemistry it39s the change in size andor shape ofa system at rest I Work PV Work o A Constant pressure times the change in volume PAV o B Occurs in a system at rest no gravitational potential energy no kinetic energy o C Work is a path function o P j PV work takes place when a gas egtltpands against a force regardless of whether or not the pressure is constant lleat engines o A Turn a piston on its side to remove gravity at heat not temperature and the energy is changed entirelyquot into PV work as force against the piston o Not all heat is turned into work I l Piston hits a max we have to push it back in I 2 The process of pushing it back in increases temperature I 3 This requires more work to compress it than was expended to expand it I 4 So we use a cold reservoir to cool the piston I 5 Diagram V I 6 Diagram egtltplained Due to the conservation of energy heat entering the engine q must equal net work done on the engine w plus the heat leaving the engine qc a qh W Clc Second Law of Thermodynamics o A Definition Heat cannot be changed into work in a cyclical process 70 22 o 4 Electronic energy I a Potential electrical energy created by the attractions between the electrons and their respective nuclei F p lquotlcclmnic I b o S lntermolecular potential energy also called bond energy I a Energy created by the intermolecular forces between molecular dipoles O O T OO I b Intcrmolltc11lni polvnlial o 6 Rest mass energy I a Energy predicted by E mc2 Rest nmlts I b Zeroth Law of Thermodynamics o A efinition Two systems in thermal equilibrium with a third system are in equilibrium with each other o B That is two bodies in thermal equilibrium share a thermodynamic property which must be a state function its called Temperature Temperature o A Temperature increases with an increase in thermal energy o B Thermal energy the sum oflnternal kinetic energy I l Translational energy I 2 Rotational energy I 3 Vibrational energy o C Remember extensiveextensive intensive energymoles temperature Temperature Measurements o A Celsius at l atm water freezes at 0 C and boils at lOO C o B Kelvin Celsius 273 lowest possible temperature ever OK o C Increase of l C increase of IK Enthalpy ll o A H U P o B At constant pressure AH AU PAV o C AI q at I l Constant pressure I 2 Closed system at rest I 3 P work only gt Enthalpy is not a measurement of some intuitive property shit s man made E Enthalpy is not conserved lillte energy universal enthalpy does not remain constant E Differs from energy in that enthalpy assumes no work was done by the gas G Extensive property ll Units Jmol l Note for an ideal gas enthalpy only depends on temperature Enthalpy Standard States o A Again there are not actual objective values for enthalpy so scientists made shit up I l Chosen temperature T I 2 Pressure l bar 750 torr or I05 pascals o B Element in the above standard state usually at 25 C but can be any value enthalpy O Jmol Enthalpy Standard Enthalpy of Formation AIf O O O O O O 77 Gibbs Free Energy Equations o A AG AH TAS 25 I I Every variable above refers to the system and not the surroundings I 2 Only good for constant temperature reactions o B AG O equilibrium at I I Constant temperature I 2 Constant pressure I 3 PV work only I 4 Reversible process o C AG negative I I lncrease AS universe I 2 Spontaneous Gibbs Free Energy Spontaneity Remember o A Enthalpy K o B Entropy J AH AS AG Spontaneity Negative Positive Negative All temperatures Negative low T Negative Negative Positive high T Low temperatures Negative high T Positive Positive positive low T High temperatures Positive Negative Positive Not spontaneous CHAPTER 4 Solutions 739 27 I I Number ofwater molecules needed to surround an ion I 2 Varies with size and charge ofthe ion I 3 Usually has values between 4 and 6 Electrolyte o A A compound which forms ions in aqueous solutions o B Strong electrolytes create solutions conduct electricity I I Salts I 2 Strong bases I 3 Strong acids o C Weak electrolytes compounds that form few ions in solution Names You Need to Know Name Formula Nitrite NO239 Nitrate N03quot Sul te SO32 Sulfate SO42quot Hypochlorite ClO39 Chlorite ClO239 Chlorate ClO339 Perchlorate ClO439 Carbonate C032quot Bicarbonate llCO339 Phosphate PO43quot Units of Concentration O O I Molarity M moles ofsolutevolume ofsolution I I Temperature dependent because it is per liter of solution and density changes with temperature 2 Molality m moles of solutelltilograms of solvent I I Temperature independent 3 Mole fraction x moles of solutetotal moles of all solutes and solvent I I Temperature independent 4 Mass percentage mass of solutetotal mass of solution X lOO 5 Parts per million ppm mass of solutetotal mass of solution x I06 Normaity the equivalentsquot ofa solution depends on the type of reaction taking place eg HZSO4 has two equivalents in an acid base reaction because it can donate two protons Problem Strategy 77 30 B When added to a liquid some will reach the surface ofthe solution and reduce the amount of surface are available for the liquid molecules C That is these fuckers use up prime real estate but don39t break free into the gaseous phase D Less prime real estate less molecules breaking free while the I surface area ofthe surface and 2 volume above stay the same so E From PV nRT we know that ifn decreases at constant volume and temperature then pressure P has to decrease proportionally and it does by RaouIt s Law F Raout s Law PV xaPa I I PV vapor pressure ofthe solution I 2 xa mole fraction ofthe liquid I 3 Pa vapor pressure ofthe pure liquid I Vapor Pressure Volatile Solutes in Ideal Solutions 0 O O A Volatile Solute A solute with vapor pressure B Like nonvolatile solutes it will compete for the surface area the prime real estatequot C Unlike nonvolatile solutes some ofthe volatile solute molecules will escape from the surface and contribute to the vapor pressure D lfthe solution is ideal solvent and solute have similar properties RaouIt s Law can be used to nd the partial pressures of both the solvent and the solute E Raout39s Law PV xaPa xbPb I I PV total vapor pressure ofthe solution I 2 Paxa partial pressure contributed by the respective solvent I But wait bitches It doesn39t stop here What if the solution isn39t ideal I Vapor Pressure Nonideal Solutions 0 O I lfthe solution is not ideal the intermolecular forces between molecules will be changed 2 Whereas with nonvolatile and volatile solutes in ideal solutions it was a simple the added solute shit takes up space and doesn39t evaporate or it doesquot here the added solutes alter the energies ofthe original molecules themselves Aw shit 3 Why aw shit Because this means either less or more energy will be needed by the molecules to break free into the gaseous phase causing huge deviations from what Raoult39s Law predicted I Vapor Pressure Raoult39s Law Recap O O O O I Nonvolatile Solutes Ideal Solutions lf97 ofthe solution is solvent then the vapor pressure will be 97 ofthe vapor pressure ofthe pure solvent 2 Volatile Solutes Ideal Solutions If 97 ofthe solution is solvent then vapor pressure will be 97 ofthe vapor pressure ofthe pure solvent PLUS 3 ofthe vapor pressure ofthe pure solute 3 Nonideal Solutions I I Negative Exothermic Heat of Solution I a Stronger bonds are formed I b Fewer bonds are able to break free from the surface I c Negative deviation of the vapor pressure from Raoult39s law I 2 Positive Endothermic Heat of Solution I a Weaker bonds are formed I b More bonds are able to break free from the surface I c Positive deviation ofthe vapor pressure from Raoult39s law 4 Graphical Representation 3920 32 Solubility Product Constant Example Continued o A Okay but what ifwe dissolve I mole of llaF It would completely dissociate o B Spectator ions lla ions have that no effect on equilibrium ideally o C Common ion effect when ions that may or may not be from the same source cause an equilibrium shift in accordance with Le ChateIier39s principle but does not affect Ksp I I F ions do affect equilibrium I 2 By Le ChataIier39s principle the reaction will shift in the direction that reduces the F39ion which is the left 4 This reduces the solubility of BaF2 5 24 x lO395 gtlt2gtlt l2 I 6 Because the equilibrium is shifting to the left x and even 2gtlt is going to be much smaller I 7 Drop the 2x and solve forjust X2 I 8 X 24x IO395 Solubility Guidelines o A Insoluble compound with water solubilities ofless than 00I mol Lquot o B Ionic compounds are soluble that contain I Nitrate N03 2 Ammonium lIH4 3 Alkali metals Li lIa K Rb Cs Fr 4 Halogens Cl39 Br I o C Ionic Compounds are insoluble that contain I I Silver mercury and lead compounds Ag Hg22 Pb o D Sulfate Compounds SO42 are soluble but are insoluble ifthey contain I I Mercury lead and the heavier Alkaline Earth metals Hg22 Pb Ca2 Sr Ba239 Ra2 o F The heavier alkaline metals Ca2 Sr Ba are soluble when they contain I I Sul des S239 I 2 Hydroxides OH39 o G Generally insoluble compounds except for the cases mentioned above are I I Carbonates phosphates sul des and hydroxides CO3239 PO43 S2 OH Gas Solubility o A Temperature I I Solubility is inversely proportional to temperature at low temperatures increasing the temp decreases the solubility I 2 At higher temperatures the entropy factor takes over AG AH TAS o B Pressure I I Solubility is directly proportional to pressure o C Shaking causes bubbles to coalesce decreasing solubility They escape the solution o D Salt nucleates gas bubbles and causes them to coalesce decreasing solubility They escape the solution Solubility Factors o I Solubility is affected by I A Pressure I B Temperature o 2 The solubility of liquids and solids are not largely affected by the above factors Solubility Factors Henry39s Law o A Henry39s Law I I Gases in an ideally dilute solution increase in pressure ofgas a over a solution is directly proportional to the solubility of gas a ifthe gas does not react with or dissociate in the solvent I 2 Holds true when pressure is low o B Equation I C kaPV I I C solubility ofthe gas a in moles per liter I 2 ka Henry39s Law constant which varies I 3 PV vapor partial pressure of gas a above the solution 39239 O 36 A Slope when not zero is inversely proportional to speci c heat only not mass B Mass does not change during phase change Phase Changes Heat of Fusion and Vaporization O O A Heat of fusion I I Enthalpy changes associated with melting I 2 Endothermic positive enthalpy values I 3 lncreases volume I 4 lncreases molecular movement I 5 Increase entropy positive values B Heat of vaporization enthalpy change associated with boiling endothermic I I Enthalpy changes associated with boiling I 2 Endothermic positive enthalpy values I 3 Increases volume I 4 lncreases molecular movement I 5 Increase entropy positive values Phase Changes Freezing and Condensation O O A Heat of freezing I I Enthalpy changes associated with freezing I 2 Exothermic negative enthalpy values I 3 Decreases volume I 4 Decreases molecular movement I 5 Decrease entropy negative values B Heat of condensation I I Enthalpy changes associated with condensation I 2 Exothermic negative enthalpy values I 3 Decreases volume I 4 Decreases molecular movement I 5 Decrease entropy negative values Phase Changes Water 0 I Liquid water can absorb more energy with less temperature change than either ice or gaseous water Phase Changes Enthalpy Review 0 O A Enthalpy is a state function thus the exact same amount of heat is absorbedreleased for reversible processes eg melting freezing vaporization condensation and sublimation deposition B AG AH TAS thus temperature determines what phase change is favored spontaneous Phase Diagrams O O O A Phase Diagram Indicates the phase ofa substance at different pressures and temperatures B Each section represents a phase C The lines marking the boundaries indicate where phases are in dynamic equilibrium I I Note solid and liquid phases can be in equilibrium with the vapor phase regardless of pressure or temperature I 2 Thus all 3 phases of water can exist at l atm and 0 C which a phase diagram wouldn39t seem to agree with Phase Diagrams Descriptions 0 O O A Triple point where solid liquid and gas are in dynamic equilibrium B Critical Temperature temperature above which a substance cannot be lique ed no matter how much pressure is applied C Critical Pressure the pressure necessary to produce liquefaction while the substance is at the critical temperature what the fuck I thought it couldn39t be lique ed Edit The critical temperature is the temperature above which liquefaction cannot be achieved but still can be achieved at the critical temperature D Critical Point Critical temperature and critical pressure 3926 39 o C Water potential I I Higher pressure 9 lower pressure Colligative Properties Osmotic Pressure Explained o A Explained I I Divide pure water by a membrane permeable only to water and not the solute I 2 Add solute to one side it cannot permeate the barrier I 3 Entropy forces water to move to the other side to equilibrate the solution let39s say it achieves a perfect equilibrium I 4 Keep adding solute I 5 Water will keep migrating to make a dilute solution but think the more and more water that moves over 9 the higher the liquid on that side ofthe tube will rise 9 pressure increases P pgAy I 6 Eventually a balance is struck between entropy vs pressure I 7 Osmotic Pressure is the extra pressure on the solution compared to other side ofthe tube o C Analogy osmotic pressure is the force pulling water into the solution whereas hydrostatic pressure is the force pushing it out not technically correct because pressure Is a scalar and has no direction but a good analogy nonetheless o D Equation H il IRT I I M molarity not molality or mass which is opposite of boiling point elevation and freezing point depression o E Osmotic Potential I I Definition partial measurement ofa system39s free energy a Pure water is not itself targetedquot for osmosis because it is completely dilute why would solvents move against their gradients to dilutequot it further b Since free energy is in part a measurement of entropy something that is completely dilute has zero potential entropyquot ie there is no chance some solvent is going to dilute it cause dissolution and increase entropy I 2 Pure water arbitrarily assigned an osmotic potential value of zero I 3 Solute added osmotic potential becomes negative a Solution now has potentialquot to be diluted in an entropy driven manner I 4 At constant temperature and constant pressure a Constant temperature and pressure means entropy is the only force at work I 5 water flows from higher osmotic potential to lower osmotic potential a Entropy is increased o F Water Potential I I Definition The potential ofwater molecules to move from a hypotonic solution more water less solute to a hypertonic solution less water more solutes essentially the same as free energy I 2 Is a function of I a Temperature does not have to be constant b Pressure does not have to be constant c Solute concentration I 3 Water moves from higher water potential to lower water potential when two solutions are separated by a membrane permeable to water but not solute I 4 Diagram explanation when at equilibrium points A pure water and B solution have the same water potential but point B has lessquot more negative osmotic potential than point A I 5 Diagram 3920 O 43 C WARlllllG this does not mean that weak acids have strong conjugate base it may be weak or strong The weaker the acid the stronger it39s conjugate base but that doesn39t mean it is a strong base Check this motherfucking diagram 4 l Strong Acids an Bases for the MCAT i l o A Strong acid stronger than hydronium I l Strong base stronger than hydroxide I think o Weak acid weaker than hydronium I l Weak base weaker than hydroxide I think Strong Acid Formula Strong Base Formula Hydroiodic acid HI Sodium hydrogtltide llaOH llydrobromic acid HBr Potassium hydrogtltide KOH Hydrochloric acid HCl Amide ion lll l239 Nitric acid HNO3 Hydride ion l l39 Perchloric acid l lClO4 Calcium hydrogtltide CaOH2 Chloric acid llClO3 Sodium ogtltide lla2O Sulfuric acid HZSO4 Calcium ogtltide CaO pkl Conjugates Continued A Amphoteric substance that can act as either an acid or a base depending on the O O O O environment B Polyprotic acids can donate more than one proton C iprotic l Donate just two protons 2 Can also be called polyprotic 3 Second proton is so weak that it39s effect on pH is negligible rule ifthe llta values differ by more than I03 4 It should be noted that percent dissociation decreases with increasing acidity this means acids dissociate less in more concentrated solutions Le Chatelier s 5 This does not mean that concentrated solutions are less acidic Say it again l Acid dissociation decreases with increasing acid concentration 2 Acid strength increases with acid concentration 4392 47 a xx00l x 62x lOquot0 I 6 Solving for x requires a quadratic formula fuck that noise We make the assumption that x lt 5 of 00l I 7 After throwing out x a xx00l 62x lOquot0 I 8x25x lO396H5ltpH lt6 Finding the pEl Weak Base Example o A Same exact steps just nd pOH and subtract that from I4 Salts o A Salts lonic compounds that dissociate in water I l The higher the charges between the two ions the harder it is to dissolve them in water o Composed of both I l Metal I 2 llonmetal o C Upon dissociation create acidic or basic conditions o pH predicted by comparing the conjugates ofthe respective ions Salts Example o A Na and Cl are the conjugates of NaOH and HCl respectively o B Thus llaCl dissociates neutral solution Salts Example 2 o A llH4llO3 composed of conjugate acid ofthe base NH3 and the weak conjugate base ofthe strong acid N03 respectively o B llH4 acidic C NO neutral super weak base fgt Thus llll4llO weakly acidic Salts Weak Lewis Acids o A Remember All cations act as weak Lewis acids in aqueous solutions except I a Alkali metal cations I b Heavier Alkaline Earth metal cations Ca2 Sr Ba Titrations o A Titration drop by drop mixing of an acid and a base o B Purpose nd unknown by comparing to titrant o C ApH ofthe unknown as acid or base added sigmoidal curve Titrations Strong Acid and Strong Base p H o A o B Portion ofthe graph that most closely represents a vertical line the midpoint ofthis line is called the equivalence point or the stoichiometric point Titrations Equivalence PointStoichiometric Point 47 49 o I Measure the pH ofa given concentration ofthe acid o 2 Measure the pH halfway to the equivalence point ofa titration o 3 Find the pKb ofthe conjugate base o 4 Cannot measure the amount of base needed to neutralize the acid Titrations Henderson Hassebach How to Find pH at Half Equivalence Point o A HendersonHasselbalch is simply a form ofthe equilibrium expression Ka 39 l llta l lA39l lA 39 2 llta l lA39l lA I 3 Log rule logllta logH logA39HA 39 pamppHb MWFWD I 5 pH pKa logA39HA Titrations HendersonHasselbalch How to Find pH at Equivalence Point o A Cannot use HH to nd the pH at the equivalence point o B Must use Kbof conjugate base I I Find Kbfrom Kaand KW I 2 At equivalence point Conjugate base moles acidvolume acid volume of base used to titrate I 3 Unless the base has no volume then the volume ofthe base Conjugate base at equivalence point will not be equal to original acid Titrations Henderson Hassebach Finding the pH at Equivalence Point vs Half Equivalence Point o A Half equivalence point 39 l K l39lA39lquotlA 2 llta HA lquotlA 3 Log rule logllta logH logA39HA pamppHb MWFWD 5 PH Pllta l08A l39lA o B Equivalence point I I Kb KWlta I 2 Equilibrium expression Kb OH39HAA39 39 3 OH lltbA39HA I 4 logOH39 pOH I 5 l4 pOH pH Titrations Buffers o A Buffer the spot in a titration speci cally the half equivalence point where the most amount of acid or base can be added with the smallest change in pH o B To make a buffer I I Choose an acid with a pKaclosest to desired pH of buffer solution I 2 Mix equal amounts ofthat acid and its conjugate base I 3 Goal buffer gtgtgt outside base or outside acid o C NOTE the buffer depends on the ratio ofthe acid to base diluting it with water won39t do anything o D Summary tons ofa weallt acid and its conjugate base 40 51 I Second proton is much weaker acid than rst 2 That is second proton acid strength ltltlt rst proton acid strength 0 Grailh CHAPTER 7 Eiectrochennistry 3911 Potentials A Electric potential E electric potentials are associated with redox reactions because electrons are transferred and electrons have charge O Potentials Sll E O O O O O 54 4 Summary moles Ce4to reach equivalent point 2x moles Sn2 in solution A Standard Hydrogen Electrode SllE used to separate the potentials ofa reaction into oxidation and reduction components called halt reactions Potentials Halt reaction A Halfa component ofa redox reaction Every half reaction must be accompanied by another C Half reactions are usually listed as reduction potentials with oxidation potentials just being the opposite llalt reactions at 25 C to memorize I Strongest oxidizing agent top left 2 Strongest reducing agent bottom right Standard Reduction Potentials at 25quot C Half reaction Potential E uquotuq 30 9 Au5 150 Og 4H39aq i lo gt 11201 123 Pt339uq 2e A Pt 12 F g739nqi 20 gt Ag 080 Hg quotzIq 21 gt Hgl 080 Cu39nq e gt Cu 052 PACu3 aq 4 20 gt Cult 031 2H aq 2e gt H303 000 Fequotaq 36 gt Fe 0036 Ni2aq 2equot gt Nis 023 t 7 p 2 p vIquot F39 f quot 391 s 74 39 quot T 39U 1 quotW quotquot 151 1 h 393 l1 v39 f 1 H4214 39391 l39 I s 4 3 Potentials Electric Potential A Electric potential has no absolute value but rather arbitrary assignments based on the zero value ofthe half reaction at SHE O 2H2e399 H2 2 E 000V Potentials Electric Potential Example A Find the potential 2Au3 3Cu 9 3Cu2 2Au Separate into two half reactions O O I 2Au3 3e399 Au E 5O v 2 3Cu 9 Cu 2e39 o34v 21 a Second half of bottom reaction nal reaction of aerobic respiration EA 57 I 3 This converts chemical energy to electrical energy GalvanicVoltaic Cell Components o A Multiphase series of components no component is in more than one phase o B All phases must conduct electricity o C One must be impermeable to electrons if not electrons would come to equilibrium quickly due to free movement I I lmpermeable phase ionic conductor that carries current in the form ofions I 2 lmpermeable phase an electrolyte solution called a salt bridge o D Symbolization T ElE T I I T terminals conductors metal wires I 2 E electrodes conductors I 3 I ionic conductor salt bridge o E Voltage Electromotive force potential difference between T and T GalvanicVoltaic Cell Electrodes o A Anodes I I Negative sign I 2 Oxidation half reaction occurs here o B Cathodes I I Positive sign I 2 Reduction half reaction occurs here o C Electrode may refer to I I Strip ofmetal only or I 2 Strip of metal electrolyte solution it39s submerged in half cell o D Both terminals must be made ofthe same material GalvanicVoltaic Cell Cell Potential E o A Cell Potential EElectromotive force emf I I Potential difference between the two terminals when not connected I 2 Always positive always has chemical energy than can be converted to work I 3 Affected by a Concentrations ofthe solutions in the half cells b Reactions ofthe solutions in the half cells c Temperature ofthe solutions in the half cells d NOT the length ofthe wire connecting the half cells doesn39t make sense thinllt resistivity of a wire pla o B Connecting terminal I I Reduces the potential difference due to internal resistance I 2 Potential difference decreases as current increases o C Current I I Flow of positive charge through the load in opposite direction of electrons I 2 Pathway of electrons and thus the opposite of current a Anode electrons are repelled from here b Through the load c Cathode electrons are attracted to here d Thus current ows from the cathode to the anode o D Load the resistance SHE GalvanicVoltaic Cell Diagram Explanation o A Process Below I I H2 gas bubbles off platinum catalyst plate H ions produced I 2 Platinum Pt plate carries electrons through wire to silver Ag strip I 3 Ag accepts electron converts it to solid silver and allows a CI to solvate in the solution 3927 61 I 5 Always requires the Nernst equation to solve for the cell potential o llalf Reactions I I Adding the two half reactions E O I 2 Must use the Nernst equation to nd the potential o C Entropy I I Nature wants greatest entropy I 2 Thus the more concentrated side will try to become less concentrated electrons flow accordingly o Potential I I Concentration cells tend to have small potential Concentration Cell iagrarns o A Diagram 1 RCLI Cat Ox 9 Fe N I t I II 39Ic L mm H ru M ll ITquot It p K Ii Iv I39c39 A Iv Concentration Cell o llernst Equation for potential at 25 C I I le2 both a product left side and reactant right side I 2 Substitute for Q the Fe ratios on either side I 3 Result for the case above E E 0062log00lOl a n 2 because 2 electrons are used each time the reaction occurs b E O o C Entropy I I Nature wants greatest entropy I 2 Thus the more concentrated side will try to become less concentrated electrons flow accordingly I 3 Observe this above A More ions on the right side than the left side right Right B Left Side o I So solid Fe on the left side is trying to increase the number of ions by undergoing oxidation reactions 61 Electrolytic Cell 62 o 2 It does this happily with a positive thus spontaneous potential of 044 C Right side o l lons are trying to reduce their numbers by taking the electrons from the right side and reducing themselves to pure iron o 2 Now this goes against spontaneity with a negative potential of 044 So why the fuck does this happen o 3 Because entropy would rather see the sides balanced in terms of reactants which overrides the electric potential factor o 4 This can be seen in the equation E E 006nlogproductsreactants o 5 That is if E is positive then the reaction is spontaneous o 6 Well in concentration cells E is zero so whatever is being subtracted from it must be negative zero minus a negative positive o 7 When the numerator products from the right half ofthe equation in the left half cell is smaller than denominator reactants from the left half ofthe equation in the right half cell logproductsreactants negative o 8 Zero minus a negative positive E spontaneous makes sense more concentrated side tries to become less concentrated o 9 Science bitches o A Electrolytic cell I Hook up a power source across the resistance ofa galvanic cell and force the cell to run backwards o B Potential negative o C Terminals I Anode a Marked positive o D Diagram b Oxidation still occurs here I 2 Cathode a Marked negative b Reduction still occurs here I 3 Why a Galvanic cells are used to provide energy to an external load b Thus the electrodes are labeled so that the negative electrons will flow toward the positive electrode 639
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