SN1 and SN2: Kinetics, Stereochemistry and What Decides the Route · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Two ways to swap one group

Science · Chemistry · ages 19-20
Name ______________________   Date ____________

  1. What stereochemical outcome does SN2 give at a chiral centre?

    • A racemic mixture
    • Inversion
    • No change at all

  2. Doubling the nucleophile leaves the rate unchanged but doubling the substrate doubles it. What is the route?

    • SN2
    • SN1
    • Neither route fits

  3. A tertiary alkyl halide can react by SN2.

    Circle one:   True   False

  4. Which solvent change pushes a borderline reaction toward SN2?

    • Moving to water, which cradles ions
    • Moving to acetone, which leaves the nucleophile bare
    • Removing all solvent entirely

  5. A chiral substrate reacts and the product is a racemic mixture. Which route ran?

    • SN2 through backside attack
    • A route with no intermediate and no attack
    • SN1 through a flat carbocation

  6. A secondary halide meets a strong nucleophile in acetone. What dominates, and what changes in aqueous ethanol?

    • SN2 with inversion, turning to SN1 with racemisation
    • SN1 with racemisation, turning to SN2 with inversion
    • SN2 in both solvents with no change

  7. A methyl halide sits in a polar protic solvent with a weak nucleophile. A student predicts SN1. What is wrong?

    • Methyl cations are too stable for SN2
    • Methyl cannot form a stable cation, so SN2 still wins
    • Solvents never affect the route

  8. A student reads the SN1 rate law straight from the balanced equation. Why is that wrong?

    • Balanced equations show only totals, while orders come from experiment
    • Rate laws are never measured at all
    • SN1 has no balanced equation
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Two ways to swap one group W1-mt_BiCjJw2eJF-s1

  1. Inversion · Backside attack flips the centre in one motion.
  2. SN1 · Only the substrate appears in the slow step.
  3. False · Bulk blocks backside attack, so tertiary goes SN1, never SN2.
  4. Moving to acetone, which leaves the nucleophile bare · Bare nucleophiles strike from behind.
  5. SN1 through a flat carbocation · Both faces were open, so both configurations formed.
  6. SN2 with inversion, turning to SN1 with racemisation · Secondary substrates let the solvent decide.
  7. Methyl cannot form a stable cation, so SN2 still wins · Substrate class forbids SN1 here whatever the solvent.
  8. Balanced equations show only totals, while orders come from experiment · Only doubling tests reveal who collides in the slow step.
Worksheet · LightMySky