10 questions🇬🇧English
🧲 Haloalkanes & Nucleophilic Substitution – A-level
Chemistry · A-level — practise naming, nucleophilic substitution mechanisms, reactivity, elimination and CFCs.
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Questions
What is the IUPAC name of CH₃CHBrCH₃?
2-bromobutane
1-bromopropane
3-bromopropane
2-bromopropane
20s
How is 2-chloro-2-methylpropane, (CH₃)₃CCl, classified?
Tertiary haloalkane
Quaternary haloalkane
Primary haloalkane
Secondary haloalkane
20s
Why is the carbon atom in a C–Br bond attacked by nucleophiles?
The carbon has a lone pair that attracts them
The C–Br bond is non-polar and very weak
Br is more electronegative, so the carbon is δ+
Br is less electronegative, so the carbon is δ−
20s
In the mechanism of OH⁻ with bromoethane, where does the curly arrow showing nucleophilic attack start?
A lone pair on the oxygen of OH⁻
The δ+ carbon atom of bromoethane
The O–H bond in the hydroxide ion
The C–Br bond, moving towards Br
30s
Bromoethane is heated under reflux with KCN in ethanol. What is the organic product?
Ethylamine
Ethanol
Propanenitrile
Ethanenitrile
30s
Why does 1-iodobutane hydrolyse faster than 1-chlorobutane?
The C–I bond enthalpy is higher than C–Cl
Iodine is more electronegative than chlorine
The C–I bond is more polar than C–Cl
The C–I bond enthalpy is lower than C–Cl
30s
Bromoethane reacts with ammonia to make ethylamine. Why is ammonia used in excess?
To neutralise the ethylamine as it forms
To reduce further substitution of the amine
To make ammonia act as a base, not a nucleophile
To stop ethene forming by elimination
30s
Ethanolic AgNO₃ is added to 1-chloro-, 1-bromo- and 1-iodobutane at 50 °C. What is seen first?
A cream precipitate with 1-iodobutane
A yellow precipitate with 1-iodobutane
A white precipitate with 1-chlorobutane
A cream precipitate with 1-bromobutane
30s
Which conditions favour elimination rather than substitution when 2-bromopropane reacts with KOH?
Warm KOH dissolved in water
Cold KOH dissolved in water
Cold KOH dissolved in ethanol
Hot KOH dissolved in ethanol
30s
Why can one chlorine radical from a CFC destroy thousands of ozone molecules?
It is formed again in each termination step
It reacts with ozone to make stable Cl₂
It is regenerated in the second propagation step
It is released again each time UV splits O₃
30s