Chemistry233
Chapter2ProblemSet
AcidsandBases–GeneralInformation
Bronsted-LowryAcid–Proton(H+)donor
LewisAcid–Electronpairacceptor
+
Bronsted-LowryBase–Proton(H )acceptor
LewisBase–Electronpairdonor
Analyzingtheacidityoforganicacids:
• AsthepKaofacompounddecreases,itsacidityincreases.
• Asthestabilityofitsconjugatebaseincreases,theacidityoftheacidincreases.
o Conjugatebasestabilityfactors:
§ Foratomsinthesamerow,anegativechargeonamoreelectronegativeatomismorestable.
§ Foratomsinthesamecolumn,anegativechargeonalargeratomismorestable.
§ Aconjugatebasewhosenegativechargeisdelocalizedthroughresonanceismorestable
thanonethatisnot.
§ Inductivestabilization:nearbyelectronwithdrawinggroupshelptostabilizeanegative
chargebyinductivelywithdrawingelectrondensity.
§ Orbitalconsiderations:Anegativechargeonansp-hybridizedcarbonismorestablethanone
onansp2-hybridizedcarbon,whichismorestablethanoneonansp3-hybridizedcarbon
• Topredicttheequilibriumofanacid/basereaction,writeoutthefullreactionandlabeltheacid,
base,conjugateacid,andconjugatebase.Comparethestabilityofthebaseandconjugatebase.The
reactionwilllietothesideofthemorestablebase/conjugatebase.
1) Classifyeachbondbelowasionic,non-polarcovalent,orpolarcovalent.Forthepolarcovalent
compounds,indicatethedirectionofthedipole.
Na Br
H Cl
H 3C CH2CH 3
H 3CO H
Br
H OH
H 3C CF 3
H CH 3
H 3C OH
Br Mg Br
Br
F Cl
Li
2) Determinetheformalchargeoneachoftheboldatomsbelow.
H
H 3C
C
C
H 3C
HC
HC
H
C
N
CH
CH
CH 3
H 3C
O
O
C
H2
C
CH 3
C
H
H
H 3C
C
H
CH 3
H 3C
CH2CH 3 H2
C
OH 2
H
H 3C
P
H
H 3C
N
H
H
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Chem.233–Chapter2ProblemSet
3) DrawLewisstructuresforthefollowingions.
Addoneelectronforanegativecharge.
Subtractoneelectronforapositivecharge.
C 3H 7O -
C 4H12N +
C 3H 7+
a)
on oxygen
on nitrogen
on carbon
b)
on carbon
C2H 3ClN a)
on nitrogen
b)
on carbon 4) Usecurvedarrowstoshowtheflowofelectronsforeachoftheacid-basereactionsshownbelow.
O
H
O
+
O
+
O
H
H O H
H
+
O
+
+
OH
H
O
H
+
H
O
O
H
+
O
HN
O
+ H 2N
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Chem.233–Chapter2ProblemSet
5) Foreachofthepairsofcompoundsbelow,identifythemoreacidiccompound.Listthefactorthat
ledyoutoyourchoice.
OH
and
SH
and
H Br
O
O
H F
H
and
OH
NH 2 and
H
and
OH
SH and H Cl
O
H
H
and
H
O
OH
and
O
O
S
H
S
H
and
O
S
N
H
and
H and
H
H
H
Cl
OH and
F
O
OH and
OH
O
O
F
and
OH
O
O
O
H
H
OH
OH
and F
F
Cl
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Chem.233–Chapter2ProblemSet
6) Rankeachsetofcompoundsinorderofincreasingacidity.
a.
NH 3
H 2O
HF
b.
HBr
HCl
HF
c.
H 2O
H 3O+
HO -
d.
NH 3
H 2O
H 2S
e.
CH 3CH2CH 3
ClCH2OH
CH 3CH2OH
7) Drawtheconjugateacidforeachofthefollowingbases.
H
O
H
NH
NH 2
O
O
O
In this example there are two potential sites for protonation. Which would be preferred? Why? Page 4 of 6
Chem.233–Chapter2ProblemSet
8) Drawtheconjugatebaseforeachcompoundshownbelow.
OH
H 3O
H 2O
O
NH 2
OH
H 2SO 4
NH 3
9) Foreachsetbelow,determinewhichspeciesisthestrongerbase.
NH 2
or
O
or
Br
or
NH
OH
S
O
Cl
Cl
or
Cl
or
O
O
O
or
O
or
or
NH 2
Cl
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Chem.233–Chapter2ProblemSet
10)Foreachreactionshownbelow,useunevenequilibriumarrowstoshowwhetherthereaction
favorsreactantsorproducts.
O
O
+
H 2O
+
OH
O
OH
H
+
+
H
OH
O
+
HF
+
OH
+
HI
I
+
H 2O
F
11)UsecurvedarrowstoshowthereactionbetweeneachLewisacidandLewisbasebelow.Drawthe
productforeach.
H 3C NH 2
+
H Cl
H 3C NH 2
+
BF 3
+
H Cl
Page 6 of 6