Popular in Course
verified elite notetaker
Popular in Department
This 25 page Reader was uploaded by Sabby Fowler on Monday September 28, 2015. The Reader belongs to a course at a university taught by a professor in Fall. Since its upload, it has received 14 views.
Reviews for LB172FinalExamStudyGuide.pdf
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 09/28/15
LB 172 Final Exam Study Guide Recap 0 Enthalpy HAH 0 State function doesn t matter how you get to the end just the different between end and start 0 Sum of internal energy within a molecule compound or system 0 If no work enthalpy heat 0 Examples of changes in enthalpy I Combustion bomb calorimetry phase changes 0 Endo vs Exo O AH endothermic I ex Melting ice put energy in 0 AH exothermic I ex Freezing ice energy is released I kJmol per reaction I doesn t change I How to calculate it 0 Bond energies formed broken 0 Least accurate averages 0 Calorimetry O AHchT 0 AH AHfusmass 0 Hess s LawProductsReactants 0 Most accurate 0 Q I Q AH mass I J ouleskiloj oules I heat given off I changes based on amount undergoing reaction 0 Energy 0 Do molecules store energy I Energy is released when bonds are formed I It takes energy to break bonds I Couch example I Products have lower internal E when compared to ATP Thermo II 0 First Law of Thermodynamics 0 Energy is neither created or destroyed 0 Second Law of Thermodynamics O A processreaction will be spontaneous if the disorder in the universe increases Ientropy I Spontaneity I A reaction will occur without any outside intervention no catalyst no heat no work I Does NOT mean it will happen quickly 0 Ex Diamondljgraphite graphite is more stable than diamonds I Q How does spontaneity affect thermodynamics 0 If you ONLY think about enthalpy all exothermic reactions will be spontaneous no E put in all endothermic reactions would not be require E I NOT TRUE 0 Ice cub melting spontaneous 0 C is spontaneous amp endo 0 Sugar dissolving in water is spontaneous amp endo I Another component Entropy 0 Entropy s O O The amount of molecular disorder I Ientropy ldisorder in the system I if S gt 0 then I disorder I if S lt 0 then I disorder AS Sfmal Sinitial A chemical process will proceed if the amount of disorder in the universe is O I The universe will favor disorder why 0 Probability the ways we can be ordered 1 ways we can disordered infinite Sklnw I S entropy I K constant 138 103923 I W number of ways to disorder MacroMicro states I Macro of item in container I Micro position of item in containe The state with the highest entropy disorder will have the greatest dispersion of energy I Solid least disorder LLiquid LGaseous most disorder IMoles lDisorderEntropy Examples of increase in S I Going from liquid to gas or solid to liquid Examples of decrease in S I Gas to liquid liquid to solid I 2N2g 02 g III 2N02 g I 3 mols I 2 mols How to calculate entropy I ASsySIXII ZSprod ZSreact I Use appendix values I Coefficients matter 0 Units JK or JmolK 0 NOTE just because ASsys is positive does NOT mean the reaction is spontaneous ASuniV must be positive in order to be spontaneous I ASuniV Aern ASsurr I ASsurr AHT I If ASuniV gt 0 spontaneous I If ASuniVlt 0 not spontaneous I Aern ZAHpmd ZAHreact I Watch units 0 Third Law of Thermodynamics the entropy of a perfect crystal at zero K is zero I Reason why there s no A in S products Reactants exact value Gibbs Free Energy G 0 The maximum amount of work energy that can be released to the surroundings by a system 0 The amount of free energy provided by a reaction I For a constant temperature and pressure system 0 AerI1 AerI1 TASIXII 0 If AerI1 negative Ispontaneous 0 If AerI1 positive I not spontaneous O OPPOSITE of entropy 0 If a reaction is not spontaneous the reverse reaction is spontaneous I Qualitatively determining spontaneity 0 Exothermic increase entropy I Always negative always spontaneous at all temps O Endothermic decrease entropy I Always positive never spontaneous O Exothermic decrease entropy I Spontaneous at low temperatures 0 Endothermic increase entropy I Spontaneous at high temperatures 0 Quantitatively O 1AG1mAHImTASIXII I Watch units convert AS I k I Use appendix values I Difference between AH and AG and finding heat given off q or free energy available 0 AH and AG per reaction don t change 0 Heat given off q or free energy available positive change based on quantity AHG moles I Finding temp at which is becomes spontaneous Set AG 0 solve for T I It is at equilibrium at 0 so it would be spontaneous at any value less than the T you solved for O 2 AG ZAGprod ZAGreact appendix values 0 3 Hess s law with AG values for known reactions 2 ip leave it etc Gases I Who cares intro to gases 0 We breath it I Air 781 N2 209 02 09 Ar 000005 H2 rest of noble gases lt002 H20 0 4 C02 0035 CH4 0002 0 Environmental implication greenhouse gases C03 N02 CH4 etc OO Gases observed generated in reactions Gas laws I real life scuba diving Gases at room temp H2 02 N2 F2 C12 03 Noble gases CH4 C2H6 C3H8 HF HCl HBr HI C0 C02 NO N02 NH3 SOZ HCN Toxic gases NH3 CO HCN C12 mustard gas phosgene WWI Physical properties of gases 0 Occupy the space in which they are contained 0 Most relative kinetic energy 0 Much less dense than liquids and solids 0 Much more compressible than liquids and solids 0 Variables involved in gases pressure temp volume moles of gas 0 gas laws only apply to gases Pressure 0 What is it I The force as a result of the molecules colliding With the walls of their container I Molecules collide randomly I Collisions are elastic I Increase in collisions increase in pressure I Pressure forcearea in SI units Nm2 1 Nm2 l pascal I Pascal too small measure in atm I mmHg torr divide by 760 to get in atm I IPressure IVolume 0 Inverse relationship 0 Ex Scuba diving gas oxygen pressure on lungs if you don t breath your lungs explode 0 Potato chip bags shocks on cars airplanes I Boyles Law 0 P1V1 P2V2 Volume 0 I Volume lMoles I ex De ated vs in ated tire football breathing I water bottle demo explosion as moles of gas increases volume increases 0 Avogadro s Law I V1n1V2n2 Temperature 0 IVolume I Temperature 0 Charles Law I V1T1V2T2 Combined Gas Law 0 P1V1 T1 P2V2 T2 Ideal Gas Law 0 PVnRT O llTemp IlVolume Imoles IPressure I Pressure in atmosphere 0 If in torrmmHg divide by 760 I Volume in liters I 11 moles I R is constant 0082057 Latm mol K I Temperature in Kelvin I Never negative I Celsius 273 O STP standard temperature and pressure I Temp 0 degrees Celsius 273 K I Pressure 1 atm 0 Density 0 Density of gases is much lower than solids or liquids 0 Density massvolume 0 Density pressure molar mass RT 0 Partial Pressure 0 Dalton s law of partial pressure I The total pressure is equal to the sum of each of the partial pressures 39 PA XA PTotal I XA mole fraction nA ntotal Kinetic Molecular Theory 0 KB 12 mv2 I 3 assumptions 0 assume molecules take up no volume 0 assume the average Kinetic Energy at a certain temperature is the same for all molecules KE proportional to T O assume when molecules collide these collisions are elastic meaning there is no loss in energy 0 There is a lot of empty space between gas particles compared to that of solid and liquid particles 0 Average KB of gas particles is directly proportional to Kelvin temp 0 As you raise temp of gas average speed of particle increases I Don t be fooled into thinking all gas particles are moving at the same speed I Since KE 12 mv2 if average KE is same at a given temp small molecules will move faster I Particles of the gas atomsmolecules are constantly moving 0 Attraction between particles is insignificant 0 When moving gas particles hit another gas particle or the container they do not stick but rather bounce off and continue moving in another direction I Like billiard balls 0 The speed of gas molecules 0 U2 average squares of the particles velocity 0 root mean square a weighed average velocity ms Urms o PVnMU2 j3RT UrmS M O O R 8134 Jmol O T kelvin 0 Um1S ms I Mean Free Path gas molecules trael in a straight line until it collies with another molecule I Speed represents it traveling in a vacuum 0 M molar mass kgmol 0 Effusion vs Diffusion O Diffusion I Dispersing gas molecules form high concentrations to low concentrations 0 EX Wears perfume scent disperses throughout the room 0 Effusion I The movement of gas molecules from a small opening 0 EX Helium balloon slowing falling I Graham s Law 0 Rate of diffusioneffusion O Inverse relationshms rM 0 Formula 2 2 r 2 M1 0 Whenever given ratio it is assuming other value is 1 I What is meant by ideal 0 Assume I No attraction between molecules I Molecules don t take up any volume 0 Typically true at STP but I At low temps 0 Molecules are moving slower 0 More attraction 0 VI than ideal I At high pressures 0 Less space between molecules 0 Size matters Vllthan ideal IP than ideal 0 Phase Diagrams O Supercritical uid I Substance with properties of both a liquid and a gas 0 Example decaf coffee I Critical point I Triple point 0 Phase changes I SL fusion I LDG evaporation I SEIG sublimation I GDS deposition I GDL condensation Molecular Orbital Theory 0 Molecular orbitals are the summation of atomic orbitals 0 of atomic orbitals of molecular orbitals I Determines the molecular structure by treating the electrons as moving throughout molecular orbitals 0 Bond order electrons in bonding electrons in antibonding 2 0 Higher bond order more stable 0 If you remove bonding electrons decrease BO amp stability 0 If you remove antibonding electrons increase BO and stability 0 Naming boxes 0 Begin at bottom 0 Start with S then P 0 If 1 square I sigma 0 Next 1 square above it is I sigma antibonding 0 If 2 square pi 0 Next 2 square above it I pi antibonding 0 HOMO amp LUMO O HOMO highest occupied molecular orbital O LUMO lowest unoccupied molecular orbital O E from the HOMO attack and move to the LUMO 0 Valence Bond Theory vs Molecular Orbital Theory 0 VBT good general idea of molecule great for large molecules I Fails to predict physical properties of some molecules 0 Ex O2paramagnetic can t tell from lewis or VBT 0 Can predict the unpaired electrons from MOT O MOT illustrated moving electrons identifies energy levels of electrons can predict existence of molecules 39 Can answer why CO is toxic 0 Comperes for sites with O2 for heme protein BO 2 0 CO has 2 fewer valence electrons BO 3 0 Has a higher BO than O2 so it binds better preventing O2 from being transferred throughout the body 0 Metals have mobile electrons Band theory Band Theory 0 Combining a whole bunch of atomic orbitals in one long band of molecular orbitals O Electrons are delocalized across the whole band 0 Conduction Band antibonding amp Valence Band bonding 0 The Gap is the gap between valence and conduction band 0 Varies depending on material 0 For metals gap is in general non existent 0 For insulators too big of a gap preventing electrons from moving 0 Thermal vs Electrical conductivity 0 In order to be a good electrical conductor it must be able to transport charge well therefore free moving electrons O In order to be a good thermal conductor one must only transport the mechanical energy of molecular motions Semiconductors 0 Medium band gap 0 How to improve conductivity of semiconductors Heat Voltage Doping 0 Doping O N Type negative type I Add something With more valence electrons I Increase probability of an electron With enough E to bridge the gap I EX Adding Phosphorous 5 valence to Silicon semiconduct 4 valence 0 PType positive type I Add something with less valence electrongs I Creating holes Where electrons can travel holes empty orbitals I EX Adding gallium 3 valence to Silicon 0 Combine ptype amp ntype I ex LED much more efficient than incandescent as noted by heat given off by incandescent Solids I Solids are structural material 0 Wood steel glass concrete etc I Used in electronics 0 Conductors insulators I Optic Materials 0 Fiber optics glass 0 Energy storage 0 Batteries Metallic Solids I Held together by metallic bonds electrostatic attraction full and full I Repeating unit metal cations in a sea of electrons I Conductive thermally amp electronically 0 Cold to the touch absorbing your heat energy 0 Highest range in melting points I When heated its electrical conductivity decreases 0 Why Additional vibrations in each atom absorbing E impedes the ow of electrons Molecular Solids I Held together by IMFs 0 Repeating unit molecules 0 Lowest melting point 0 Typically considered insulators thermally and electrically C6H1206 H20 C10H22 Ionic Compounds 0 Held together by an electrostatic attraction I Repeating units ions cations and anions 0 high melting point I As a solid poor electron conductors 0 Brittle relatively hard materials Network Solids I Held together by covalent bonds 0 Repeating Unit nonmetal covalently bonded atoms 0 Very high melting point I Very hard 0 Ex Diamond graphite SiC Quartz I Insulators in general I Gooddecent thermal conductors 0 Why Rigid and can transfer vibrational thermal energy from one aom to another I Large band gap Summary I Network solids Ionic compounds Molecular solids and Metallic solids are all crystalline solids 0 As opposed to amorphous solids without form 0 Crystalline set unit cell repeating unit I Melting Point 0 Highest Network Solids 0 Ionic compounds 0 Metallic solids 0 Lowest Molecular Solids I Covalent bonds trump ionic bonds which trump IMF s Solutions I Who cares 0 We deal with solutions all the time reactions physical phenomenon we re composed of solutions I Solutions are not just aqueous 0 You can have a solid liquid or gas solute with a solid liquid or gas solvent I Examples I Solute gas Solvent gas I air I Solute gas Solvent liquid I pop I Solute liquid Solvent liquid I vodka I Solute solid Solvent liquid I salt water I Solute solid Solvent solid I brass I Henry s Law Pressure 0 Gases as a solute Why does pop fizz when the can opens O Other examples I Breathing on a plane amp scuba diving don t do both in same 24 hours I Diving high Pressure increase N2 solubility under water 0 Flying low pressure N2 will bubble out due to broken capillaries O Decrease Pressure Decrease solubility of gas 0 S gas M Kh constant X P atm I Kh differs based on the gas 0 Why does He have smallest Kh Smallest molecular weight and just LDF 0 Increase MW easier to distort I Solubility of gases Increase as pressure increases decreases as temperature goes up 0 Temperature 0 Increase in temp will excite gases causing them to move more quickly I Why warm popbeer goes at faster I Cold water fish vs warm water I Global wamring impact 0 IMF s like dissolves like solutessolvents with similar IMF s will have increased solubility I Solubility of liquids and solids 0 Increase temp will increase solubility 0 IMF s like dissovles like 0 Ex you decrease amount of NaCl that can be dissolved in water when you decrease the temp 0 Super saturated solutions 0 The amount of solute exceeds the amount of what should be soluble 0 Recrystallizations O Decrease in temp add a crustal use a glass stir rod scratch beaker 0 Why do solute and solvent mix 0 Increase in entropy disorder I What about enthalpy 0 Ex HCl water heat is given off exo NH4NO3 water feels cold endo 0 If endo IMF s in solution gt IMF s in solutesolvent 0 AH solution AH solute AH solvent AH mixture Colligative Properties 0 Affected by how much stuff you put in not what the stuff is Vapor Pressure 0 Whats in the space above water when water is boiling Water vapor 0 If there is no increase in Temp is there a Vapor pressure I Yes some molecules have enough KE to enter gas phase 0 Add nonvolatile solute ot hexane I Vapor pressure will decrease I Fewer molecules going into gas phase I More stuff in the way 0 When adding a solute it gets in the way of solvent evaporation 0 VP solution X solvent x VP pure solution I X solvent moles of solvent moles of solvent solute I Temp embedded in VP value 0 What about adding ionic compounds as solutes I I 0 Dissociative constant Van Hoff factor 0 of ions produced from one unit of a compound 0 VP equation X solvent moles of solvent moles of solvent solute xi 0 Assume i 1 if molecule 0 What if in a liquid liquid solution both liquids are volatile Both exert a VP 0 Raoult s Law I VP solution VPa VP b I VPa Xa VP purea 0 If calc VP is lower IMFS stronger together than alone if higher IMF s lower together Boiling Point Elevation 0 When VP externalatmospheric pressure then substance boils I Add salt to water to boil decrease in VP increase BP 0 Why bubbles before boiling Dissolved oxygen no longer soluble in water water becoming a gas 0 ATBpmXKBpXi 0 AT should be positive elevation I Add to known BP 0 m molality moles solute kg solvent 0 KBP solvent constant 0 I dissociation constant Freezing point depression 0 Why we put salt on roads and antifreeze in window wiper uid 0 ATP m X KF X i 0 AT will be negative take absolute value of depression 0 Subtract from known FP Osmotic Pressure 0 What is osmosis O Diffusion of water across a semipermeable membrane 0 Semipermeable only lets solvent through not solute 0 Water low to high concentration of solute I In an effort to reach equilibrium by reducing concentration of solute by increasing volume of water I Osmotic pressure Tl pressure required to stop osmosis 0 Who cares IV uids saline solution correct salt concentration of your body I Isosmotic equilibrium 0 Hyperosmotic shriveled high concentration out of cell 0 Hyposmotic swollen low concentration out of cell 0 EX Pickling brine very salty cucumbers shrivel in water to try and dilute brine I Osmotic pressure formula T MRTi where M is molarity mols solute L solvent R 082057 constant L atm mol K T in kelvin O I dissociation OOOO Reverse osmosis used in purification of water solute can t pass Chemical Kinetics I Study of molecules interactionsreactions and the speed in which they react I Who cares 0 Chemical reactions timewise O Synthesisl chemical companies form products in a reasonable time 0 Pharmaceuticalsl how long it takes things to react I Length it takes to work in body I Expiration dates 0 Knowing how the reaction occurs mechanisms not on exam 2 I Improve rate of reaction I Inhibition of reaction 0 How do we determine rates 0 Change in concentration over time 0 Al B I Rate AB At I Or Rate AA At 0 Generally decrease in concentration decreases rate 0 2H1 I H2 12 0 rate AH2 At AIz At 12 AHI At 0 HI will be consumed twice as fast when compared to forming product based on mole to mole ratio 0 Factors that affect rate 0 Collision theory I The ability of reactions to collide and interact with each other I When they collide they must collide with enough E to overcome E barrier activation energy I The orientation of molecules is important for reacting 0 Concentration I Increase Concentration increase rate in general I The rate law the exact relationship between concentration reactants and rate I Rate k AX By 0 Determine X and y experimentally not from a balanced equation 0 K rate constant I A concentration of A I Xy rate order I Rate orders 0 Zero order concentration will not affect rate 0 Only case where ate is independent of concentration 0 First order rate is proportional to concentration 0 Second order rate is proportional to the square of concentration 0 How to find 0 Select two trials where one concentration is changing but one is constant 0 Divide rates set that equal to fraction of concentration to the X power 0 Take natural log of both sides and solve for X 0 Overall rate order SUM of individual rate orders I Integrated Rate Laws 0 Rate vs concentration time I Incorporate the change in rate vs concentration over a period of time 0 Summations of instantaneous rates over a period of time 0 First Order 0 LnAtA0 1ltt Natural log of concentration vs time Negative slope A concentration at that time A0 initial concentration k rate constant t time 0 Don t need actual rates to solve just the ration between the two 0 Second Order OOOOOO O 1At kt 1A0 0 Positive slope O 1 concentration vs time 0 Zero Order 0 At 1ltt Ale 0 concentration vs time 0 positive slope I When you plot 0 LnA and get a straight line I first order 0 1 A and get a straight line I second order 0 A and get a straight line I zero order I Halflife 0 nuclearradioactive decay is always first order 0 Carbon dating half life of 5730 years Phosphorous dating half life of 147 days 0 Half life is how long it takes for a concentration to be cute in half 0 2X half life IA of concentration 3X 18 of concentration etc 0 Always get k from half life then use regular equation 0 First order I Tm 0693k 0 Second order 39 T12 lk A0 0 Zero order 39 T12 Ah2k 0 Temperature I Increase in temp increase speed of molecules increase number of collisions increases likelihood of molecules reacting increases rate I Increase in temp increase speed increase number of collisions increase KE increase likelihood two molecules will collide with enough energy to pass over the activation energy barrier I Arrhenius equation 0 Increase activation energy decrease rate constant 0 Increase temperature increase rate constant 0 Catalyst I Lower activation energy required I Orient molecules in correct orientation to react Reaction Mechanisms 0 Series of individual steps that when added together equal the overall reaction 0 Example 0 Overall 2N02Cl IZNOZ C12 0 1St Step N02C1 I N02 Cl 0 2nd Step N02C1 Cl N02 C12 0 Intermediate Cl 0 Intermediates formed temporarily and then used up during the reaction 0 Never added in the overall reaction 0 Intermediate is NOT the same as a catalyst I A catalyst it used regenerated and is added to the overall reaction 0 Elementary reaction step individual step 0 Unimolecular reaction step involving ONE molecule 0 Bimolecular reaction step involving TWO molecules 0 Termolecular reaction step involving THREE molecules 0 The Slow Step rate determining step 0 This step dictates what the rate law looks like stoich matters here Molecularity Rate Law A I products 1 Rate kA A A I products 2 Rate kA2 A B I products 2 Rate kA B A A Al products 3 rare Rate kA3 A A B I products 3 rare Rate kA2B A B C I products 3 rare Rate kABC I If slow step has intermediates 0 Rateforward Ratereverse Look to another step containing that intermediate Isolate the concentration of the intermediate and combine the k values Substitute this into the rate law This method can make biomolecular reactions look termolecular I Can never prove a mechanism only disprove O can have reasonable certainty about what most likely happens 0 Energy Diagrams can tell us Mimiquot nmimnn O O O O 0 Activation energy 3quot 9139 3 mmquot a a h 0 Exo h1ghlow vs Endo lowh1gh I O Reactlon rate slow step LE m E Reactants E Products I H1ghest act1vatlon energy E g Renew 3 energy E absorbed O Of SthS no released pr dums no Reactants I number of bumps Reaction Progress Reaction Progress Enothermic Enclothermic reectlon reaction Chemical Equilibrium I Chemical kinetics was talking about SPEED of a reaction I Chemical equilibrium talks about HOW FAR a reaction will go 0 Relative amounts of reactants vs products 0 Keq products reactants 0 In order to be at equilibrium Rateforward Ratereverse lt Dynamic Equilibrium I At dynamic equilibrium concentrations no longer change but aren t I aAbBcCdD I Keq Cc Dld Ala Bb 0 W Law of Mass Action always equals same at EQ regardless of initial concentrations I Who cares 0 Acid reactivity biological impact pH enzymes Pharmaceuticals reactivity solubility 0 K values 0 Small values produce mostly just reactants proceeds to the left Kltltl 0 High values product mostly just products proceeds to the right Kgtgtl 0 If k approx 1 neither direction favored proceeds about halfway 0 If reverse reaction invert K If multiply coefficients by a factor raise K to that value If adding two equations together multiply K values K values corresponds to concentration of reactants amp products ONLY AT EQ 0 If given amounts of reactantsproducts at EQ can solve for Keq vice versa 0 Kc vs Kp 0 K concentration M Cc Dd Aquot 1 Bb O Kp pressure atm KcRTAn O A PA RT or PA A RT 0 Kp Kc if total number of moles of gas on products total number on reactants 0 K vs Q 0 K equilibrium constant I Amount of reactants amp products at EQ ONLY 0 Q reaction quotient I Amount of products and reactants at any time during the reaction I Can find Q to determine which direction reaction is going I O lt K RIGHT need more Droducts I g gt K LEFT need more reactants I Same equation as K 000 0 Le Chatlier s Principle Equilibrium stressors 0 If a reaction undergoes a stress it will shift it s EQ to alleviate that stress 0 Phases matter gases and aqueous solutions are always in EQ expressions I Never include solids their concentrations don t change I Never include pure liquids ex Water 0 Changing concentrations of products and reactants I lproductslreactants LEFT Q gt K I llreactantsproducts RIGHT Q lt K 0 Adding amp Removing heat I I heat favor endothermic reaction heat reactant endo I I heat endo right 0 I heat endo left I Iljheat favor exothermic reaction heat product exo 0 Iheat exo left I Iheat exo right 0 Changing the volume I I volume favor side with most moles of GAS I I volume favor side with least moles of GAS 0 Changing pressure I lpressure favor side with fewer moles of GAS I lpressure favor side with more moles of GAS 0 Adding a catalyst I Does nothing to EQ I Catalyst speed up forward AND reverse rate Steps to Solving EQ problems 1 Writebalance equations 2 Determine direction of reaction a If any concentrations aren t listed assume they start at zero reaction will go towards these molecules b Can determine by finding Q QgtK left QltK right 3 Fill in ICE initial change equilibrium table 4 Use values at equilibrium and fill them in to K expression 5 Solve for X 6 Using x values determine concentrations at EQ Acids amp Bases 0 Arrhenius definition 0 Acid Ka a substance that produces H30 in water 0 Base Kb a substance that produces OH in water 0 Bronsted Lawry 0 Acid H donor 0 Base H acceptor 0 Amphoteric can act as an acid or base ex Water 0 Example NH3 H20 I I NH4 OH39 0 Base NH3 0 Acid H20 0 Conjugate Acid NH4 O Conjugate Base OH39 O Conjugate pairs NH3 amp NH4 and H20 amp OH39 0 Strong Acids and Bases O No EQ for strong acid and bases one way reaction arrow 0 Strong Acids HCl HBr HI HNO3 H2SO4 HClO4 HC103 lt borderline 0 Strong Bases Group I and Group 11 metal hydroxides NaOH KOH LiOH etc 0 Conjugate acidsbases of weak acidsbases vs strong acidsbased 0 Weak acidsbases their conjugate acids and bases CAN act as actual acids and bases when the reaction is reversed 0 Strong acidsbases their conjugate acids and bases CANNOT act as actual acids and bases the reactions cannot be reversed 0 Determining Acid Strength Based on K and pK O K1 Iacid strength lconjugate base strength 0 UK Ibase strength conjugate acid strength 0 pK1 acid strength 0 Ipr base strength I pKa 39 10g Ka 0 Lewis Acid e acceptor 0 Ex AlC13 Metal Cations Fe3 Sn2 0 Have empty orbitals to accept e 0 Lewis Base e donor 0 Ex OH NH3 H20 0 KW l x 103914 H30 x OH 0 If H30 gt OH acidic 0 If OH gt H30 basic 0 pH log H30 H30 1039pH 0 pOH log OH OH 1039pH pH pOH 14 Determining pH in strong acids and bases 0 Assume complete dissociation I So if you start With 050 M HCl you Will end With 050 M of H30 I note group II metal hydroxide bases 0 BaOH2 I Ba2 20H 0 So if you start With 050 M of BaOH2 you Will end With 100 M of OH Determining pH of weak acids and bases 0 Make an ice table 0 Determine concentration of H3O or OH at equilibrium Significant Figures for pH 0 Goes by decimal places 0 So a pH of 234 has 2 significant figures not 3 Percent Ionization O IAcid I Percent Ionization 0 Percent Ionization final initial x 100 I For shortcut if percent ionization lt 5 you can use it How salts affect pH 0 Separate salt into cation and anion and observe What each Will do in water If it forms a strong acid or base it Will have NO EFFECT because this is impossible Group 1 and 2 Metals Will never have an effect All other metal Will have an effect Any reaction that Will have an effect Will be at equilibrium Qualitatively deciding I If cationanion forms OH in water the solution Will be basic or pH gt 7 I If cationanion forms H30 in water the solution Will be acidic or pH lt 7 O Quantitatively I If cationanion forms OH in water set up ICE table for this reaction I If cationanion forms H30 in water set up ICE table for this reaction OOOOO Mixed Acids amp Polyprotic Acids Mixed acid example 0 Acid 1 Ka 49 x 103910 O Acid2Ka 18 x10394 0 Acid two is contributing more to H30 because it has a larger K31 value making it a stronger acid 0 pH is largely determined by the stronger acid Buffers Buffer a solution that is resistant to pH change Carbonate is the most popular buffer in our blood How Because it contains LOTS of conjugate pairs Ex HNOZ H20 ll H3O N02 0 Lots of HN02 and N02 0 If a strong acid is added I HCl NOT I HNOZ Cl 0 If a strong base is added I NaOH HN02 lNaNOz H20 0 How can we make buffer 0 O O O O O O O 0 Add weak acid and its conjugate base in the form of a salt I Ex HN02 and KN02 Add weak base and it s conjugate acid in the form of a salt I Ex NH and NH4Cl Solution of weak acid and strong base limiting I Ex HN02 and NaOH Solution of a weak base and strong acid limiting I Ex NH3 and HCl How to solve these problems Find what is left to affect pH after the reaction has gone to completion I Limiting reactant excess Set up Ice table of what is left I Put conjugate pairs on OPPOSITE sides of reaction Best buffers when pH pKa when HA A lowest pH for effective buffer is when base 110 acid highest pH for effective buffer is when base 10 acid How buffers maintain pH Lots of weak acid and its conjugate base I If strong acid is added conjugate base will neutralize it I If strong base is added weak acid will neutralize it For buffer problems if both weak acid and base are present in initial solution make sure to add these initial values in later ICE tables Titrations 0 Strong Acid and Base Titrations O O 0 Initial pH is the logsolution initially in solution ignore what is being titrated in Equivalence point is always 700 Find moles of both find the difference divide by total volume L take log of that pHpOH 0 Weak Acid and Strong Base Titrations O O O 0 Initial pH use ICE table to find of just weak acid Equivalence Point pH gt 7 Before Equivalence Point limiting reactant find what s left in solution ICE table After Equivalence Point limiting reactant find excess of strong base divide by total volume take log 14 that value pH 0 Weak Base and Strong Acid Titrations O O O 0 Initial pH use ICE table to find of just weak base Equivalence Point pH lt 7 Before Equivalence Point limiting reactant find what s left in solution ICE table After Equivalence Point limiting reactant find excess of strong acid divide total volume log 0 Titrations of Polyprotic Acids 0 Will have more than one equivalence point 0 H2803 NaOH I H20 H803 o HSO3 NaOH l H20 803 0 Indicator 0 Color change base on change in pH occurs from an indicator gaining or losing H which affects its color Solubility 0 How much a compound dissolves in water KSp 0 Common Ion Effect I Adding a soluble ion that is also present in EQ expression I EX Suppose CaOH2 is added to l M of C3C12 solution I CaClz s I Ca2 aq 2Cl39 s I Need less CaC12 products I solubility 0 If HCl was added it would react with OH39 Nuclear Chemistry 0 Radioactivity the emission of subatomic particles 0 particles B particles n0 positron etc I Uses for radioactivity 0 Radiation therapy gamma knife treat cancerous tumor 0 Imaging I PET scan F18 labeled glucose I 131 thyroid I P32 phosphoproteins I cancertumors I Fe59 bloodspleen I Te99 heart liver lungs I Ti201 heart Types of radioactivity 0 0t Decay alpha decay O Unstable nuclide emits an Ot particle Ot particle 42 X or 42 He 4 mass 2 number of protons EX 22288 Ra I 42 X 21886 Rn 0 daughter nuclide Largest mass highest ionizing power Least penetrating power due to mass ecay beta decay Unstable nuclide emits a 3 particle Neutron I Proton e39 EX 3215 P I 3216 S 01 e I beta particle Much smaller less ionizing power More penetrating power 0000 U OB 00000 I Gamma Rays 00 V O No mass no charge 0 Couples with some other radioactivity 0 Ex 23892 U I 23490 Th 42 or 00 v O Gamma rays are harnessed and utilized for gamma knife because high penetration due to zero mass 0 Positron Emission O No mass has a charge 0 Proton I neutron positron 0 Ex 2211 Na I 2210 Ne 01 e El positron 0 Electron Capture 0 Electron is absorbed O Proton e39 I neutron 0 Ex 10048 Cd 01 e 10047 Ag 0 ALL nuclear decay first order 0 LnAt Ao KT 0 Tm 0693K 0 Nuclear Fission O Dividing of an atom splitting 0 Ex 23595 U 10 11 I 9336 Kr 14 56 Ba 310 n O Boron control rods n0 absorbers 0 Fukishima 0 Lost power I no water pump I water super heated I boiled off I thermolysis I Thermolysis splitting of water H20 I 2H2 02 produces hydrogen gas explosions 0 12 potentially radioactive substances released into the air I 1131 Cs 137 St 90 Ba 140 I Cs amp St majority in a few years I Cesium is readily absorbed by the body acts like sodiumpotassium NaK channels I I131 is a radioactive substance sucked up by the thyroid people took KI to fill up thyroid so it wouldn t absorb any of the radioactive kind I Giona Indicent 1987 O Nucelar disaster I 4 dead 250100000 affected I Cs 137 stolen from a iron capsule in hospital sold to junkyard owner blue substances many people were exposed and got sick Mass Defect I Where the energy is coming from I In nuclear reactions the loss of mass is converted to energy 0 E me2 where m is mass lost in kg c is speed of light 3 X 108 ms squared 0 Mass defect mass reactants mass products p no Electrochemistry 0 AcidBase reactions dealt with the transfer of protons this deals with transfer of electrons 0 Must balance atoms and charge 0 Steps for Redox Reactions 1 To identify which is losing gaining break up into two half reactions based on oxidation numbers a Qxidation ls Losing electrons OIL i Oxidation number I b Reduction ls gaining electrons RIG i Oxidation number I Ex Cu s NOg39 aq I Cu2 aq N02 g Assigning Oxidation Numbers 0 If just an element by itself I 0 ex Xe C12 Sg 0 Sum of oxidation numbers the charge on the molecule neutral 0 0 Most electronegative element gets negative oxidation state F most en followed by O Element Usual Oxidation State Exceptions Group I metals Always 1 None Group II metals Always 2 None Oxygen Usually 2 Except in peroxides l and F20 2 Hydrogen Usually 1 Except in metal hydrides l Fluorine Always 1 None Chlorine Usually 1 Except in compound with O or F Cu s I 0 N aq I 5 03 aq 6 C11 811 I 2 N g I 4 02 g I 4 Oxidized Cu Cu s I Cu2 aq Reduced N NOs39 aq INOz g 2 Balance all non O non H numbers Cu s I Cu2 aq if 3 Add only HzO to balance oxygen atoms and only H to balance hydrogen atoms 2H 4 Add enough electrons to balance charge in each half reaction Cu s I Cu2 2 e39 le39 2H NO339 aq INOZ g H20 5 Multiply half reactions by whole numbers in order to equalize number of electrons Cu s I Cu2 2 e39 21e39 2H NOg39 aq INOZ g HZO 2e39 4H 2NOg39 aq I 2NOz g 2HzO 6 Add two half reactions cancel what appears on both sides ALL electrons must cancel Overall Cu s 4H 2NOg39 aq I Cu2 aq 2N02 g 2H20 If you have an acidic solution containing H in reactants STOP If you have a basic solution 7 Add enough OH to both sides to equal the quantity of H present combine H and OH to form HzO acid base neutralization cancel what you can all electrons must cancel Ex 8203239 aq SHZO 8 e39 4C12 I 2SO4239 10H 8Cl39 IOOH 203239 aq SHZO 8 e39 4C12 I 2SO4239 8Cl39 IOHZO Voltaic Cells Uses spontaneous chemical reaction to generate electricity Anode Oxidation losing electrons Cathode Reduction gaining electrons CaR Electrons go from cathode to anode Salt bridge 0 Transfers electrolytes between half cells I Release build up of charge I Allows reaction to continue Writing shorthand equations Anode s Anode hargeaq CathodeJ39Ch alrge aq Cathode s represents phase change represents salt bridge 0 O 0 Ex Cd 8 2Ag aq I Cd2 aq 2Ag s Anode Cd cathode Ag Cd 5 Cd2 aq Ag aq Ag 3 Hydrogen electrode standard reduction potential E0 0V 0 0 0 E cell E cathode E anode Work Eocell II F O 0 AG If AG positive E00611 negative I not spontaneous F 96 485 n moles of electrons transferred Eocell n F If AG negativeE00611 positive I spontaneous AG RT1nK O R 8314 joule version not 0082057 L atmmol K What s connected Equilibrium amp O Buffers 0 Weak Acids and Bases 0 Solubility 0 Gas Solubility 0 Gas Laws 0 AG I AG RT1nK R 8314 AG amp O Equilibrium I AG RT1nK R 8314 0 AH amp AS I AG AH TAS AS in joules so divide by 1000 0 Electrochemistry I AG E ce11n F F 96 485 0 One way reactions 0 Energy 0 One Way Reactions amp OOOOO AG Electrochemistry Nuclear Decay Energy Movement of Electrons 0 Movement of Electrons amp O O O 0000 One way reactions Reaction Mechanisms Band Theory I Electrons move from valence band I conduction band Conductivity Electrochemistry Resonance Molecular Orbital Theory 0 Strong Acids and Bases 0 Solutions amp 0 00000 IMF s Solubility Weak Acids and Bases Gas Solubility AH Gas Laws Kinetics amp 0 Gas laws 0 Reaction mechanisms 0 Nuclear Decay Band Theory amp 0 Solid Properties 0 Conductivity 0 Movement of electrons