Organic Chemistry EXAM 3 (Chapters
7 & 8) Reactions & Mechanisms
Revision with correct answers and
rationales assured excel!!
Organic Chemistry Reactions & Mechanisms Revision Guide with Rationales
1. SN2 Rate
Answer: Rate = k[substrate][nucleophile]
Rationale: SN2 reactions depend on both the substrate and nucleophile concentration
because bond breaking and bond forming occur simultaneously in a single step. Therefore, SN2
is a second-order reaction.
2. SN1 Rate
Answer: Rate = k[substrate]
Rationale: The slow, rate-determining step is carbocation formation, involving only the
substrate. The nucleophile attacks later and does not affect the rate.
3. E2 Rate
Answer: Rate = k[substrate][base]
Rationale: E2 elimination occurs in one concerted step. Both the substrate and base
participate in the transition state, making it second order.
4. E1 Rate
Answer: Rate = k[substrate]
Rationale: Like SN1, the slow step is loss of the leaving group to form a carbocation.
Therefore, only substrate concentration affects the rate.
, 5. Two-Step Reactions
Answer: SN1 and E1
Rationale: Both mechanisms proceed through a carbocation intermediate after the leaving
group departs.
6. One-Step Reactions
Answer: SN2 and E2
Rationale: Bond breaking and bond formation occur simultaneously without forming
intermediates.
7. Nucleophile
Answer: Electron-pair donor; "nucleus loving"
Rationale: Nucleophiles are electron-rich species that donate a pair of electrons to an
electron-deficient atom.
8. Polarizability
Answer: Ability of an atom's electron cloud to be distorted
Rationale: Larger atoms hold valence electrons less tightly, making them more polarizable
and often better nucleophiles.
9. Electrophile
Answer: Electron-poor species that accepts electrons
Rationale: Electrophiles possess a partial positive charge or an empty orbital that can
accept electron pairs.
10. Protonate
7 & 8) Reactions & Mechanisms
Revision with correct answers and
rationales assured excel!!
Organic Chemistry Reactions & Mechanisms Revision Guide with Rationales
1. SN2 Rate
Answer: Rate = k[substrate][nucleophile]
Rationale: SN2 reactions depend on both the substrate and nucleophile concentration
because bond breaking and bond forming occur simultaneously in a single step. Therefore, SN2
is a second-order reaction.
2. SN1 Rate
Answer: Rate = k[substrate]
Rationale: The slow, rate-determining step is carbocation formation, involving only the
substrate. The nucleophile attacks later and does not affect the rate.
3. E2 Rate
Answer: Rate = k[substrate][base]
Rationale: E2 elimination occurs in one concerted step. Both the substrate and base
participate in the transition state, making it second order.
4. E1 Rate
Answer: Rate = k[substrate]
Rationale: Like SN1, the slow step is loss of the leaving group to form a carbocation.
Therefore, only substrate concentration affects the rate.
, 5. Two-Step Reactions
Answer: SN1 and E1
Rationale: Both mechanisms proceed through a carbocation intermediate after the leaving
group departs.
6. One-Step Reactions
Answer: SN2 and E2
Rationale: Bond breaking and bond formation occur simultaneously without forming
intermediates.
7. Nucleophile
Answer: Electron-pair donor; "nucleus loving"
Rationale: Nucleophiles are electron-rich species that donate a pair of electrons to an
electron-deficient atom.
8. Polarizability
Answer: Ability of an atom's electron cloud to be distorted
Rationale: Larger atoms hold valence electrons less tightly, making them more polarizable
and often better nucleophiles.
9. Electrophile
Answer: Electron-poor species that accepts electrons
Rationale: Electrophiles possess a partial positive charge or an empty orbital that can
accept electron pairs.
10. Protonate
