Free Halogen compounds questions for AS Level Chemistry (9701), part of Organic chemistry. Each question has the answer and the marking points an examiner would look for.
Generate a full Halogen Compounds worksheet →All Organic chemistry questionsBromoethane is heated separately with aqueous NaOH and with NaOH in ethanol.
Which row shows the main organic products?
| aqueous NaOH | ethanolic NaOH | |
|---|---|---|
| A | ethanol | ethanol |
| B | ethanol | ethene |
| C | ethanoic acid | ethene |
| D | ethene | ethanol |
Answer: B
Which term is described by this statement?
“A nucleophile replaces the halogen in a halogenoalkane.”
Answer: A
2-bromo-2-methylpropane and 1-bromobutane are each heated with aqueous sodium hydroxide.
Which row gives the mechanism for each?
| 2-bromo-2-methylpropane | 1-bromobutane | |
|---|---|---|
| A | SN2 | SN1 |
| B | elimination | SN2 |
| C | SN1 | SN2 |
| D | SN1 | SN1 |
Answer: C
2-bromopropane can be converted into propan-2-ol or propene depending on the conditions. In one experiment 7.38 g of 2-bromopropane gave 1.98 g of propan-2-ol.
State the conditions needed to make each product from sodium hydroxide.
State the role of the hydroxide ion in each reaction.
Calculate the percentage yield of propan-2-ol.
Explain why CFCs are unreactive in the lower atmosphere but cause damage in the stratosphere.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | aqueous warm → alcohol; ethanolic hot → alkene aqueous NaOH, warm → propan-2-ol B1 NaOH in ethanol, heat → propene B1 | 2 |
| (b) | nucleophile; base nucleophile in substitution B1 base in elimination B1 | 2 |
| (c) | 55.0% n(2-bromopropane) = 0.0600 mol C1 yield = 55.0% A1 | 2 |
| (d) | strong C–F; UV releases Cl• C–F (and C–Cl) bonds are strong so CFCs are unreactive M1 UV in the stratosphere breaks C–Cl to form Cl• radicals that break down ozone M1 | 2 |
This question is about the halogenoalkane 1-bromobutane, CH₃CH₂CH₂CH₂Br.
Classify this halogenoalkane as primary, secondary or tertiary.
State the reagent and conditions for converting it into an alcohol.
Describe the SN2 mechanism for this reaction. Show curly arrows, partial charges and any intermediate or transition state.
Explain why this halogenoalkane reacts by this mechanism rather than the other.
State the reagent and conditions needed to form an alkene from this halogenoalkane, and name the type of reaction.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | primary primary B1 | 1 |
| (b) | NaOH(aq); heat under reflux aqueous sodium hydroxide B1 heat under reflux B1 | 2 |
| (c) | OH⁻ attacks δ+ C; transition state; Br⁻ leaves in one step dipole on C–Br B1 curly arrow from lone pair of OH⁻ to δ+ carbon B1 curly arrow from C–Br bond to Br B1 transition state with partial bonds and negative charge B1 | 4 |
| (d) | primary carbocation unstable; little steric hindrance a primary carbocation would be unstable (only one alkyl group) B1 the carbon is not sterically hindered so OH⁻ can attack directly B1 | 2 |
| (e) | NaOH in ethanol; heat; elimination sodium hydroxide dissolved in ethanol B1 heat B1 elimination B1 | 3 |
Halogenoalkanes can undergo elimination.
State the conditions for elimination rather than substitution.
Name the organic product when 2-bromopropane undergoes elimination.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | ethanolic NaOH; heat NaOH in ethanol B1 heat B1 | 2 |
| (b) | propene propene B1 | 1 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in