Haloalkanes 2022

When heated with NaOH(aq), 1-iodobutane is hydrolysed at a much faster rate than 1-chlorobutane. Which statement explains the different rates?

• The C–I bond enthalpy is greater than the C–Cl bond enthalpy

• The C–I bond is less polar than the C–Cl bond.

• The C–I bond has a C atom with a greater δ+ charge than in the C–Cl bond

• The C–I bond requires less energy to break than the C–Cl bond

A student measured the time taken for a precipitate to form when a solution of AgNO₃ was added to three haloalkanes dissolved in ethanol. Her results are presented in the table above. Predict how long it took for a precipitate to form in the test tube with 1-iodobutane.

• 330

• 50

• 120

• 810

1. Complete the definition of a nucleophile.

A nucleophile is an atom or a group of atoms that is attracted to an ............................. deficient carbon atom, where it ............................. a pair of electrons to form a new .................. bond.

When a warm aqueous solution of potassium hydroxide is added to iodoethane, a nucleophile substitution reaction occurs producing ethanol and iodide ions. What is the formula of the nucleophile in this reaction.

Haloalkanes can be hydrolysed but the rate of hydrolysis varies. Which of the following statements is true?

• CH₃CH₂I would be the fastest because the C-I bond has the biggest dipole

• CH₃CH₂Cl would be the fastest because the C-Cl bond has the biggest dipole.

• CH₃CH₂I would be fastest because it has the weakest C-I bond

• CH₃CH₂Cl would be fastest because it has the weakest C-Cl bond

The correct systematic name of the compound in the picture is:

• 2,3-dichloro-2-ethylbutane

• 2,3-dichloro-3-ethylbutane

• 3,4-dichloro-2-methylpentane

• 2,3-dichloro-3-methylpentane

Here are some statements about hydrolysis of CH₃CH₂Br . Tick all that are correct.

• If AgNO₃(aq) is added to CH₃CH₂Br a cream precipitate is formed that dissolves in dilute aqueous ammonia

• If AgNO₃(aq) is added to CH₃CH₂Br, H₂O behaves as a nucleophile

• If AgNO₃(aq) is added to CH₃CH₂Br, a cream precipitate is formed only after hydrolysis has occurred

Which is true about the haloalkanes A, B and C?

• All of them are secondary haloalkanes

• A is tertiary, B is secondary and C is primary

• A is tertiary, B is secondary and C is secondary

• A is tertiary, B is tertiary and C is secondary

Identify the mistakes in this mechanism for a nucleophilic substitution

The reaction of 1-bromopropane and OH- ions produces an alcohol. Which statement is NOT correct?

• The reaction is a substitution

• Hydroxide ions act as a nucleophile

• The C-Br bond breaks by homolytic fission

• the reaction is a hydrolysis