Chemistry II final review
Chemistry II final review CHEM 1200
Popular in Chemistry II
Popular in Chemistry
This 7 page Study Guide was uploaded by Alexi Martin on Friday May 13, 2016. The Study Guide belongs to CHEM 1200 at Rensselaer Polytechnic Institute taught by Dr. Alexander Ma in Spring 2016. Since its upload, it has received 95 views. For similar materials see Chemistry II in Chemistry at Rensselaer Polytechnic Institute.
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Date Created: 05/13/16
Chemistry Final Review Highlighted questions = exam questions May be a question Question distribution: Chapter easy medium hard total 19 0 3 2 5 1213 1 2 1 4 14 2 2 0 4 15 1 3 1 5 17 2 2 0 4 18 0 3 1 5 20 1 3 1 5 21 2 1 0 3 Karty 3 5 2 10 23 0 4 1 5 Total 12 28 10 50 Calculations 23 (simple and hard) One or 2 questions from lab quizzes (unchanged) From exam 1,2 and 3 14 from them 10 are untouched the rest are somewhat changed Organic Mechanisms (Karty 5,7,8) [all physical examples are on powerpoint] simple elementary reactions bimolecular reactions unimolecular reactions stereochemistry and stereospecificity organometallic reagents predicting reaction mechanisms organic lab topics Simple elementary reactions Coordination is a formation of a bond Proton transfer Heterolysis bond breaking Nucleophilic addition and elimination involves a nucleophile Electronic addition and elimination, involve an electrophile 1 Bimolecular reaction single step stereospecific substitution SN2 alkyl halide> leaving group elimination E2 reaction rates: 2nd order rate (SN2)=k[Nuc:][RX] rate(E2)=k[B:][RX] see powerpoint for free energy diagrams Unimolecular reaction Substitution SN1 1st step rate determining step the formation of carbocation SN1 R or L attack not stereospecific Elimination E1 3 products multi step Reaction rates: rate (SN1)=rate(E1)=k[RX] always in competition Free energy diagrams see powerpoint Carbocation rearrangements (SN1 and E1 only) 1,2 hydride shift preferred 1,2 methyl shift Zaitsev’s rule: elimination reaction, favors the most substituted alkene as the major product Stereochemistry and stereospecificity SN2 vs SN1 SN2 stereospecific, Sn1 non stereospecific E2 beta proton has to be anti coplanar from the leaving group X Organometallic reagents Alkyllithium RLi treat as R and gringard R’MgBr e rich carbocation will attack almost anything very reactive nucleophile Aluminium hydride and borohydride treat as H hydride and H e rich Predicting reaction mechanisms Rate determining steps for multistep reaction mechanisms such as Sn1 and E1 1st step formation carbocation slowest, RDS> 1st step (SN1 and E1) rate=k[RX] Basicity vs nucleophilicity (SN2 and E2) Basicity in elimination reactions ability to attack electron poor H of adjacent C (beta proton) Nucleophilicity in substitution reactions such as SN2 ability t attack the e poor C of the RX Predicting reaction mechanisms 5 factor reaction mechanisms E2>E1 strength attacking species: the base for elimination reactions or the nucleophile in substitution reactions Concentration: increased concentration of nucleophile favors SN2>Sn1 increase concentration E2>E1 Stability of leaving group: excellent leaving groups favor SN1 and E1>Sn2 and E2 Type of C atoms: methyl and primary C favor SN2, unless there is a carbo rearrangement then E1 and Sn1, tertiary C favor SN1 and E1 not Sn2 secondary C are neutral 2 Solvent effects: protic Sn1 and E1 aprotic Sn2 and E2 SN1 vs Sn2: Sn1 tertiary C weak nucleophilic protic solvents reduce [Nuc:], Sn2 methyl and primary C strong nucleophilic aprotic solvents (polar) increase [Nuc:] Substitution and elimination: increase in temperature increase in entropy increases the likelihood of elimination Organic lab structures IR and organic structures: alkene vs ketone , alcohol bs alkene (characteristics ) CH 3000 OH 3500 C=O 1700/1800 Thermodynamics (Ch 19) Conservation of energy and 1st law,△E=q+w, q and w done by system + done on system Work in chemical systems △H=△E+P△V △H=△E+△ngasRT at constant P, △S=q/T Entropy and 2nd law △Suniverse> 0 △Suniverse=△SSystem+△Ssurroundings △S>0 irreversible △S=0 reversible 3rd law entropy 0 at abs 0 perfect single crystal Spontaneity and gibbs free energy q=HTS at constant temperature △G=△HT△S △G= 0 equilibrium △G>0 nonspontaneous △G<0 spontaneous I △H>0 △S<0 nonspontaneous II △H<0 △S<0 temperature dependent IV △H<0 △S>0 spontaneous III △H>0 △S>0 temperature dependent Absolute entropy and standard Gibbs free energy similar to △Hf or Hess’s Law △G=sum of △Gf products the sum of △Gi reactants and △S=sum of Sf products( # mol) sum of Si reactants (# mol) maximum work wmax=△G reversible processes only estimated boiling point △Gvap=△HvapTvap△Svap=0 Tbp=△Hvap/△Svap when △G vap=0 △G and position of equilibrium chemical phase △G=0 △G=△Gnought+RTLnQ Q=[products]/[reactants]=Pproducts/Preactants Temperature dependence of K at equilibrium △G=0 Q=K △Gnought= RTlnK K=e^(△G/RT) Liquids and Solids (Chapter 12&13) intermolecular forces london dispersion (all molecules), dipole dipole (polar) H bonding (OFN) ion dipole (solutions) properties of liquidviscosity, surface tension, capillary forces, meniscus vapor pressure and vaporization Clausius clapeyron lnPvap= △Hvap/RT+ln beta (definition of boiling curve) vapor pressure vs △H vap lnP2/P1= △Hvap/R(1/T21/T1) fusion and sublimation heating curve and phase diagram q=n△Hprocess (flat lines of heating curve) or q=mc△T for slope (see powerpoint for heating curve and phase diagram ) 3 unit cells simple cubic BCC FCC (coordination number number of atoms per unit cell) packing efficiency density calculation Xray diffraction lattice spacing d ngamma=2dsintheda types of crystalline solid molecular weak intermolecular forces decrease melting ionic strong electrostatic forces increase melting soluble metallic force of delocalized e increase melting stability conduct electricity network covalent bonded strong increase melting extremely hard Solutions (Ch 14) solution equilibrium and solubility unsaturated saturated supersaturated energetics of solution at equilibrium △Hsolution=△Hsolute +△Hsolvent△Hmix △Hsolute=△Hhydration (ion dipole)△Hlattice energy solution concentration Henry’s Law Sgas=kHPgas colligative properties (depend on the number of particles not chemical properties) Raoult’s law Pa=XaPtot Pb=XbPtot P=Pa+Pb Freezing point depression FPsolventFPsolution=△Tf=mKf m=mol/kg Boiling point elevation BPsolutionBPsolvent=△Tb=mKb Osmotic pressure pi=MRT R=0.08206 M=mol/L Van’t Hoff factor iratio of # mol praticles to # mol of formula units Chemical Kinetics (Ch 15) Reaction rates A+B> C Rate law 1st order rate=k[A] or =k[B] 2nd order =k[A]^2 or rate=k[A][B] 0 order =k General rate =k[A]^n[B]^m elementary reactions Integrated rate laws 0 [A]t= kt+[A]0 1 ln[A]t= kt+ln[A]0 2 1/[A]t = kt+1/[A]0 Half life 0 t1/2=[A]0/2k 1 t1/2=0.693/k (nuclear reactions also Effect of temperature Arrhenius equation k=Ae^(Ea/RT) lnk= Ea/R(1/T)+lnA Where Ea is activation energy Ln k2/k1= Ea/R(1/T21/T1) reaction mechanisms elementary vs multistep Rate determining step is the slowest, formation of intermediates, final cannot have intermediates catalysis not in overall reaction, lowers Ea by going through alternate mechanism Acids and Bases II (Chapter 17) strong acids and bases complete dissociation such as NaOH and HCl 4 pH and pOH scales pH= log (H3O+) or pOH= log(OH) pH+pOH= 14 at 25 degrees celsius weak acids have incomplete dissociation ka=[A][H3O+]/[HA] HA+H2O>A+H3O+ (arrow goes in both directions) finding the pH or a strong and weak acid use ICE to find it at equilibrium weak bases have incomplete dissociation :B+H2O>B:H++OH kb=[B:H+][OH]/[B:] ICE to find [OH] pOH 14pOH=pH acids and bases ions and salts Depends on conjugate ions of acids and bases Strong acid neutral Cl Br NO3 strong base Na+ Ca2+ K+ neutral weak acid anion basic anion (F COO) weak base cation acidic (NH4+_ ionization of polyprotic acids acid strength and molecular structures Binary acids strength increases as you go down the column or form L to R across a period Oxyacids strength increases as the oxidation number of the central atom increases lewis acid e pair acceptor lewis base e pair donor, both nuc: and B: have lone pair of e organic acids and bases (stability of anion) charge ARIO A electronegativity of atom increase in electronegativity stabilizes charge R resonance stabilization resonance spreads out the charge I inductive effect (EWG and EDG) EWG spread out charge O hybrid orbitals sp3<sp2<sp so 50% character Ion equilibrium (CH 18) buffers Solutions and pH pOH=Pkb+log[B:H+]/[:B] pOH=pka Henderson hasselbach equation pH=pka+log[A]/[HA] or if [A]=[HA] pH=pka buffer effectiveness Effective when base and acid ratio is 1:1 buffer capacity Stoich problem number of mols of acid to base titrations Strong acid and strong base Stoich limiting reagent determine pH from excess H+ oh OH weak acids and weak bases I before addition of OH titrant pH=pH weak acid using ICE ka=[A][H3O+]/[HA] II before equivalence point (½ equivalence point) buffer problem henderson hasselbach equation pH=pka+log[A]/[HA] III at equivalent pH solution Ph weak base kb=[B:H+][OH]/[B:] divide by total volume IV excess OH [OH] leads to pOH leads to pH make sure to divide by total volume of the solution 5 diprotic acids solubility equilibria dissociation of a soluble solid into its ions Ksp=[ion 1]^coefficient[ion 2]^coefficient use ICE to figure out precipitation Q=KSP saturated no precipitation Q<ksp unsaturated no precipitation Q>ksp above saturation precipitation will occur complex ion equilibria Kf= [adduct]/[ion 1][ion 2] may be raised to coefficients Electrochemistry (Ch 20) Balance redox reaction Half reaction full reaction in basic conditions using an organic compound that is being oxidized or reduced galvanic cells Spontaneous cathode + reduction anode oxidation Standard cell notation anode|ion||ion|cathode standard electrode potentials Compare ½ cell reducation potentials Ecell=EredEox always + for galvanic cell cell potential and gibbs free energy △G= nFEcell where F=96485 C/mol e Balance redox to find n cell potential and equilibrium constant Ecell= RT/nFlnKc cell potentials and concentrations Ecell=Enoughtcell RT/nFlnQ if Q=K Enought cell= 0 electrolytic cells Nonspontaneous signs of electrode are switched not redox electrolysis and electroplating q=lt=nf compare with reduction potentials of water (H2 and O2) Nuclear chemistry Ch 21 types of radioactivity alpha, beta, gamma, positron emission and e capture balancing nuclear equations mass number and atomic number are conserved kinetics of radioactivity (half life t1/2=ln2/k) mass defect and nuclear binding energy E=mc^2 per nucleus Where E is binding energy and m is mass defect per nucleon /total # proton and neutron remember both may be per mol fusion reactions smash atoms to make bigger atoms valley of stability and magic numbers 6 Inorganic chemistry Ch 23 properties of transition metals E configurations do not have s orbital (they are cations) Atomic trends from L to R across down lanthanide contraction coordination complexes Coordination number and geometries octahedral tetrahedral square planar and linear know configurations of all ligands and chelating agents are lewis acid and base reactions monodenate vs polydentate (chelating agents) nomenclature cation then anion ate isomers Coordination linkage geometric (cis trans and fac mer ) optical crystal field theory and bonding Field splitting octahedral tetrahedral square planar and linear Field strength calculate split E=hc/gamma Strong field CN NO2 NH3 en large △oct low spin Weak field ligand OH H2O halids low △oct high spin High spin low spin complex and magnetic properties chemistry of metals Metallurgical processes Metal structures and alloys properties of inorganic C Look on powerpoint for sample organic questions 7
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