OCR A Chemistry – 'Haloalkanes' 4.2.2

Each C–X bond is hydrolysed at a different rate.

Which is the correct order of this rate and explanation?

• fastest C–F ... C–I slowest BECAUSE fluorine is the most reactive halogen

• fastest C–F ... C–I slowest BECAUSE fluorine is the most electronegative

• fastest C–I ... C–F slowest BECAUSE iodine has a larger atomic radius

• fastest C–I ... C–F slowest BECAUSE C–I has the lowest bond enthalpy

Which is the best definition of a nucleophile?

• ...is an electron pair donor

• ...is attracted to an electrophile

• ...is where a curly arrow starts

• ...is a region of electron density

Which of the following is NOT able to be a nucleophile

• [OH]^–

• an alkene

• a cation

• NH₃

Which correctly shows the compound and its environmental impact?

• A

• B

• C

• D

To measure the rate of hydrolysis of a series of haloalkanes, different haloalkanes are added to separate test tubes of ethanol.

What must be added when the stopwatch is started, and when must the stopwatch be stopped?

• AgNO₃ — a precipitate forms

• Ag₂CO₃(aq)— effervescence is seen

• AgNO₃(aq)— a precipitate forms

• Al(OH)₃— effervescence is seen

How many carbons are bonded to the halogen atom in a secondary haloalkane?

The breakdown of the ozone layer...

TICK ALL THAT APPLY

• ...is catalysed by any radical in the upper atmosphere

• ...involves heterolytic fission, caused by UV radiation

• ...involves oxygen in its atomic form

• ...is a reversible reaction

When CF₃Cl catalyses the breakdown of ozone, this species is part of the propagation steps:

TICK ALL THAT APPLY

• CF₃•

• F•

• ClO•

• OF₂

Which bond breaks in the initiation step of the mechanism for breaking down of ozone by CFCs?

• C—C

• Cl—C

• Cl—Cl

• C—F