Lesson 3.3.3.2
3.3.3.2 Halogenoalkanes: Elimination Quiz: AQA Chemistry, Unit 3
20 questions
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Lesson 3.3.3.2, Halogenoalkanes: Elimination: 20 multiple choice questions for the AQA Chemistry (7405), Unit 3: Organic chemistry, written with Revision Ninja.
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The 20 questions
-
What type of reaction occurs when 2-bromopropane is heated with ethanolic potassium hydroxide?
- Elimination
- Addition
- Oxidation only
- Free-radical substitution
-
What is the organic product of elimination from 2-bromopropane?
- Propan-1-ol
- Propane
- Propan-2-ol
- Propene
-
What is the role of the hydroxide ion in the elimination of 2-bromopropane?
- It acts as a base by removing a proton
- It acts as a radical initiator
- It acts as an electrophile by accepting a pair of electrons
- It acts as a catalyst that is not involved in the mechanism
-
What is the role of the hydroxide ion in the substitution of 2-bromopropane with aqueous OH-?
- It acts as an electrophile
- It is a catalyst with no part in the product
- It acts as a nucleophile, substituting the bromine
- It is a radical that breaks the C-Br bond
-
Why does ethanolic KOH favour elimination over substitution?
- The reagent is strongly basic and the solvent reduces the nucleophilicity of OH-
- Ethanol makes the hydroxide ion neutral with no lone pair
- Ethanolic KOH contains no hydroxide ions
- Elimination needs no reagent at all
-
Which product is formed by substitution of 2-bromopropane with aqueous KOH?
- Propene
- Propan-1-ol
- Propan-2-ol
- 2-bromopropanol
-
Which feature of 2-bromopropane leads to concurrent substitution and elimination?
- The C-Br bond is adjacent to carbons with hydrogens that can be removed
- The molecule is fully saturated with no polar bonds
- The molecule is an alkene with a C=C bond
- The bromine atom is bonded to a hydrogen only
-
In the elimination of HBr from 2-bromopropane, which bond is formed?
- A C-Br double bond
- A C-OH single bond
- A C=C double bond
- A C-K ionic bond
-
Which description of the reagent in the reaction with 2-bromopropane is correct?
- OH- acts as both a nucleophile and a base
- OH- acts only as an acid
- OH- acts only as a free radical
- OH- acts only as an oxidising agent
-
What is the mechanism of elimination of HBr from a halogenoalkane by a strong base such as OH- in ethanol?
- Electrophilic addition to a C=C bond
- SN1 with a carbocation only
- Free-radical chain reaction
- E2: the base removes a proton as the C-Br bond breaks and a C=C bond forms
-
Which of these is the product of elimination of 2-bromobutane?
- Butane
- But-2-ene
- But-1-ene only
- Butan-2-ol
-
Which product is formed from 1-bromopropane with ethanolic KOH by elimination?
- Propan-2-ol
- Propene
- Propan-1-ol
- Propanal
-
What is the molecular formula of the elimination product of 2-bromopropane?
- C3H5Br
- C3H8
- C3H6
- C3H7OH
-
Which reagent gives a mixture of alcohol and alkene from 2-bromopropane?
- Dilute HCl only
- Concentrated sulfuric acid only
- Aqueous KOH at room temperature, with some ethanolic KOH
- Chlorine gas in UV light
-
Why is the nucleophilic substitution product more likely in aqueous solution than in ethanol?
- Ethanol is a stronger nucleophile than water
- Water removes all the bromine from the molecule
- Water is a more polar solvent that favours substitution, reducing the basicity effect
- Ethanol is an oxidising agent
-
Why must 2-bromopropane be heated with KOH in the elimination reaction?
- Heating removes the alkene product immediately
- The reaction needs energy to break the C-Br bond and to remove HBr
- The reaction is spontaneous at 0 C only
- Heating converts KOH into a radical
-
A student heats 2-bromopropane with ethanolic KOH. Which product is most likely to be the main organic product?
- 2-bromopropanol
- Propene
- Propanone
- Propan-2-ol
-
Explain why 2-bromopropane gives a mixture of products when heated with aqueous KOH.
- Hydroxide acts as both a nucleophile and a base, so substitution and elimination occur at the same time
- Aqueous KOH is a radical initiator producing two products
- The reaction is reversible so both products form at equilibrium
- Potassium ions react to form two products
-
Explain why a secondary halogenoalkane is more likely to undergo elimination than a primary halogenoalkane with a strong base.
- Elimination is only possible for tertiary halogenoalkanes
- Secondary halogenoalkanes contain no C-H bonds
- Primary halogenoalkanes cannot be attacked by any nucleophile
- Secondary halogenoalkanes have more adjacent hydrogens to remove, and the steric hindrance at the carbon reduces substitution
-
Explain the role of the solvent in the competing reactions of 2-bromopropane with hydroxide ions.
- The solvent is the reagent that forms the alkene
- Ethanol reduces the nucleophilicity and basicity balance towards elimination, while water favours substitution
- The solvent is a catalyst that is consumed completely
- The solvent converts OH- into H+
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