R3.4 Electron-pair sharing reactions (HL)
15 revision questions with answers for R3.4 Electron-pair sharing reactions (HL). Read them here, or play the set as a class game on the projector. Free to host, and students join with a code.
Species that accepts an electron pair to form a coordination bond?
- Lewis base
- Brønsted–Lowry acid
- Lewis acidRight answer
- Nucleophile
What this set covers
Mechanisms at HL: Lewis acids and bases, heterolytic fission, curly arrows, Sₙ1 and Sₙ2 mechanisms and their rate equations, Markovnikov's rule for propene with HBr, and the nitration of benzene through the nitronium ion.
- Common mix-up
- Students often assume Sₙ1 and Sₙ2 give the same stereochemistry: Sₙ2 inverts the configuration at a chiral carbon, while Sₙ1 goes through a carbocation intermediate.
- Revision tip
- Draw curly arrows for one Sₙ2 step and the nitration of benzene, then state the rate equation and the slow step for each.
All 15 questions and answers
Species that accepts an electron pair to form a coordination bond?
Answer: Lewis acid
Atom that donates the lone pair in BF₃ + NH₃ → F₃B–NH₃?
Answer: Nitrogen
Bond breaking in which both electrons go to one fragment?
Answer: Heterolytic fission
What a curly arrow shows in a reaction mechanism?
Answer: Electron pair movement
Rate equation for the Sₙ2 reaction of RBr with OH⁻?
Answer: rate = k[RBr][OH⁻]
Type of halogenoalkane that reacts mainly by Sₙ1?
Answer: Tertiary
Intermediate formed in an Sₙ1 reaction?
Answer: Carbocation
Effect of an Sₙ2 reaction on the configuration at a chiral carbon?
Answer: Inversion
Halogenoalkanes react fastest by nucleophilic substitution when the leaving group is…?
Answer: Iodide
In HX addition to an alkene, H joins the carbon already bearing more H atoms: this is…?
Answer: Markovnikov's rule
Major product of propene with HBr?
Answer: 2-bromopropane
Electrophile in the nitration of benzene?
Answer: NO₂⁺
Mixture used to generate the electrophile for nitrating benzene?
Answer: Conc. HNO₃ and H₂SO₄
Type of reaction between benzene and the nitronium ion?
Answer: Electrophilic substitution
Benzene favours substitution over addition because addition would disrupt its…?
Answer: Delocalised π electrons
Play it as a class game
Play this set opens it in splycr, where you can host it for your class straight away. Hosting needs no account: put the room code on the projector, and students join from a phone with the code and their first name. Each question plays as multiple choice, and the three wrong options were written for that question.