Study&guide&for&Exam&1&&& Chemistry&301&&&& Fall,&2018&&!Check!the!Web!under!"Announcements"!for!schedule!updates!and!other!suggestions.!!!!! Review&sessions:!!Friday,!Saturday,!Sunday!before!the!exam.!!!Time!and!place!listed!on!the!Web.!!!The!review!sessions!will!not!include!new!material!nor!particularly!organized!discussions.!!They!are!designed!to!respond!to!your!questions,!so!please!come!prepared.!!!!!!! Methods!of!separation:!!ionize!to!change!solubility.!!Acids!and!bases!can!form!salts.!!Common:!!carboxylic!acids!and!amines!(base).!!Others!generally!classed!as!"neutral"!(some!exceptionsIIphenol,!etc).!!Separation!schemes,!sequential!addition!of!water!solutions!of!acid!and!base!to!the!organic!solution!of!the!mixture.!!Salts!form!and!go!into!the!water;!come!out!again!as!free!acid!or!free!base!when!neutralized,!dissolve!again!in!the!organic!solvent.!!Molecular!weight!gives!the!molecular!formula.!![do!not!attempt!to!memorize!historical!facts!or!episodesIInot!important]!!! Nomenclature:!!no!direct!questions!based!on!nomenclature.!!It!will!help!if!you!can!easily!translate!a!name!into!a!structure;!nothing!complicated!nor!tricky.!!! Correlate!structure!with!hybridized!orbitals.!! 3!hybridizations:!!sp3!=!tetrahedral!(4!sigma!bonds).!!!sp2!+!p!!=!planar!trigonal!(one!pi!bond;!3!sigma!bonds);!!sp!+!2p!=!linear!(two!sigma!bonds!and!two!pi!bonds).!!Characteristic!bond!angles.!!Relative!bond!distances!(qualitative)!for!sigma!bonds!from!different!hybridized!AOs.!!Bonding!in!ethylene,!acetylene,!C=N,!C≡N,!C=C=O,!etc.!!Label!type!of!bond!and!type!of!AOs!overlapping!in!bond.!!Dipolar!bonds,!electronegativity!effects.!!!! Polar!pi!and!sigma!bonds.!!Bond!dipoles.!!Molecular!dipoles.!!Functional!groups.!!!!Correlate!bp!and!solubility!with!structure.!Molecular!association.!!4!forces:!!ionic!(rare,!strong),!HIbonding!(specific!for!IOH!and!INH!groups;!special!dipole;!draw.!!HIbond!donor,!HIbond!acceptor);!dipoleIdipole!interactions!(permanent!bond!dipoles);!van!der!Waals!forces!(temporary!polarization).!!Compare!molecules!of!similar!MW!but!different!structure!for!relative!bp.!!Branched!vs!linear!in!vdW!interactions.!!!! Solvent!effects:!!consider!solute/solvent!interactions!vs!solute/solute!and!solvent/solvent!interactions.!!Justify!"like!dissolves!like".!! Dissol ving!usually!has!favorable!entropy,!but!enthalpy!of!selfIassociation!may!prevent!dissolving.!!Classify!solvents!as!polar!or!nonIpolar,!protic!or!aprotic.!!Examples?!!! Acidity/basicity.!!Curved!arrow!formalism.!!Ka,!pKa.!!Hess's!law!shows!two!components!in!dissociation!of!a!proton!from!an!acid!(acid!behavior):!!break!a!bond!(bond!dissociation!energy)!and!add!an!electron!to!make!an!anion!(electron!affinity).!!For!atoms!in!the!same!row!(C,N,O),!BDEs!are!similar;!electron!affinity!is!dominant.!!What!contributes!to!electron!affinity?!!Compare!stability!of!energy!of!starting!acid!with!energy!of!conj.!base.!!!! Inductive!Effects.!!The!stability!of!the!conj!base!is!usually!more!sensitive!to!local!structure!and!solvent!effects.!!Analyze!stability!of!conj.!Base.!!Free!energy!diagram!to!describe!relative!energy!of!reactants!and!products.!!Compare!2,2,2Itrifluoroethanol!with!ethanol.!!Alkoxide!anion!stability.!!!! Effect!of!steric!factors!on!acidityIIsolvent!effects!and!measurements!in!the!gas!phase.!!Compare!methyl!alcohol!and!tertIbutanol.!!Polarizability.! !! Delocalization:!!compare!carboxylic!acids!and!simple!alcohols.!!Resonance!stabilization,!rules.!!!Resonance!structures!for!ethylene,!formaldehyde.!!Acidity!of!carboxylic!acids,!propene!=!3!p!orbitals!in!a!row.!!conj!base!of!propene!is!the!allyl!anion.!!Two!equiv.!resonance!structures,!(I)!charge!at!the!end!carbons,!not!in!the!middle.!!Strong!stabilization!(compared!to!simple!carbon!anion).!!Ketones!give!enolate!anions;!analogy!to!allyl!anion!and!carboxylate!a nion.!!Protonation!of!enolate!anion!to!give!two!isomers!whether!protonation!at!O!or!at!C.!!General!system!with!three!adjacent!p!orbitals.!!!Also:!!phenols!and!tolueneIIdelocalization!into!a!benzene!ring.!!Compare!phenol!and!a!simple!alcohol.!!!!! Hybridization!effects!on!acidity:!!%!s!character!idea.!More!s!character!=!more!stable!anion.!!Compare!methane,!propene,!acetylene.!!Special!case:!!1,3Icyclopentadiene.!!Anion!has!5!equivalent!resonance!structures;!remarkably!stable!anion!considering!no!electronegative!atoms!involved.!!!!