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University of South Carolina-Columbia
CHEM 333 CHEM 333 Exam 3 Questions
and Answers 2026 Latest Update
when (H2O) solvent acts like a nucleophile in substitution reactions, its
called... Ans: solvolysis
when drawing transition states, make sure to include Ans: dotted lines
(bonds breaking and bonds forming) and partial charges
what happens if we have a chiral center where the LG is attached Ans: SN2
in energy diagrams, if bonds break, the energy Ans: goes up
in energy diagrams, if bonds form, energy Ans: goes down
in energy diagrams, the "top of the hill" is the Ans: transition state
when the bonds formed are stronger than bonds broken Ans: exothermic,
heat released
when the bonds formed are weaker than the bonds broken Ans:
endothermic, heat absorbed
what is the RDS for SN1 Ans: LG leaving
what does the unimolecular mean in SN1 Ans: one thing reacting in the rate
determining step
bimolecular in SN2 means Ans: there are two molecules reacting in the rate
determining step, the alkyl halide and nucleophile
if you were looking at an energy diagram, what would represent the rate
determining step? Ans: the highest hump
SN1 rate is dependent on Ans: the alkyl halide concentration
SN2 rate is dependent on Ans: alkyl halide and nucleophile concentration
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if you double the nuc concentration and nothing happens to the rate, what
rxn is it? Ans: SN1
if you double the alkyl halide concentration and the rate doubles, what rxn
is it? Ans: SN1 and SN2
solvent with an acidic H Ans: protic (H attached to hetero atom)
solvent without an acidic H Ans: aprotic
common protic solvents Ans: H2O, MeOH, EtOH, acetic acid, have a polar
bond
common aprotic solvents Ans: DMSO, H3CCN (acetonitrile), DMF, acetone,
CH2Cl2/DCM, THF, Et2O, benzene, toluene
what determines polarity Ans: dielectric constant
what is the dielectric constant Ans: ability to insulate opposite charges,
keep charges apart
what is the DC for polar substances Ans: greater than 15
what is the DC for non polar solvents Ans: less than 5
polar aprotic solvents solvate what Ans: cations but not anions, leave anion
alone so it can attack and act as a good nucleophile
polar protic solvents solvate what Ans: anions and cations-> anions less
likely to be nucleophile
for polar aprotic, what is more likely to be a nucleophile and what is least
likely Ans: F-, I-
for polar protic, what is more likely to be a nucleophile and what is least
likely? Ans: I-, F-
Good nucleophiles Ans: Br-
HO-
N3-
I-
© 2026 All rights reserved
University of South Carolina-Columbia
CHEM 333 CHEM 333 Exam 3 Questions
and Answers 2026 Latest Update
when (H2O) solvent acts like a nucleophile in substitution reactions, its
called... Ans: solvolysis
when drawing transition states, make sure to include Ans: dotted lines
(bonds breaking and bonds forming) and partial charges
what happens if we have a chiral center where the LG is attached Ans: SN2
in energy diagrams, if bonds break, the energy Ans: goes up
in energy diagrams, if bonds form, energy Ans: goes down
in energy diagrams, the "top of the hill" is the Ans: transition state
when the bonds formed are stronger than bonds broken Ans: exothermic,
heat released
when the bonds formed are weaker than the bonds broken Ans:
endothermic, heat absorbed
what is the RDS for SN1 Ans: LG leaving
what does the unimolecular mean in SN1 Ans: one thing reacting in the rate
determining step
bimolecular in SN2 means Ans: there are two molecules reacting in the rate
determining step, the alkyl halide and nucleophile
if you were looking at an energy diagram, what would represent the rate
determining step? Ans: the highest hump
SN1 rate is dependent on Ans: the alkyl halide concentration
SN2 rate is dependent on Ans: alkyl halide and nucleophile concentration
© 2026 All rights reserved
, 2 | Page
if you double the nuc concentration and nothing happens to the rate, what
rxn is it? Ans: SN1
if you double the alkyl halide concentration and the rate doubles, what rxn
is it? Ans: SN1 and SN2
solvent with an acidic H Ans: protic (H attached to hetero atom)
solvent without an acidic H Ans: aprotic
common protic solvents Ans: H2O, MeOH, EtOH, acetic acid, have a polar
bond
common aprotic solvents Ans: DMSO, H3CCN (acetonitrile), DMF, acetone,
CH2Cl2/DCM, THF, Et2O, benzene, toluene
what determines polarity Ans: dielectric constant
what is the dielectric constant Ans: ability to insulate opposite charges,
keep charges apart
what is the DC for polar substances Ans: greater than 15
what is the DC for non polar solvents Ans: less than 5
polar aprotic solvents solvate what Ans: cations but not anions, leave anion
alone so it can attack and act as a good nucleophile
polar protic solvents solvate what Ans: anions and cations-> anions less
likely to be nucleophile
for polar aprotic, what is more likely to be a nucleophile and what is least
likely Ans: F-, I-
for polar protic, what is more likely to be a nucleophile and what is least
likely? Ans: I-, F-
Good nucleophiles Ans: Br-
HO-
N3-
I-
© 2026 All rights reserved
