Chapter 15 - Haloalkanes

Question 1

What is a nucleophile?

Answer 1

Electron pair donator

Question 2

What are some examples of nucleophiles?

Answer 2

OH-
H₂O
NH₃

Question 3

What type of reaction do haloalkanes undergo?

Answer 3

Nucleophilic substitution

Question 4

Why does the OH nucleophile approach the electron deficient carbon from behind?

Answer 4

Minimises repulsion between nucleophile and ∂^- halogen atom

Question 5

What is the order of carbon-halogen strength?

Answer 5

C-F strongest bond (more energy needed to break)
C-Cl
C-Br
C-I weakest bond (less energy needed to break)

Question 6

What is the trend in rate of hydrolysis for different haloalkanes?

Answer 6

Increases as strength of carbon-halogen bond decreases because bond is easier to break

Question 7

How to measure the rate of hydrolysis in haloalkanes?

Answer 7

Add AgNO_3(aq) and measure time taken for precipitate to form

Question 8

When do CFCs break down and why is this bad?

Answer 8

When they reach the stratosphere and then catalyse the breakdown of the ozone layer

Question 9

What is the initiation stage in the depletion of the ozone layer using chlorine radicals? Include conditions

Answer 9

CF₂Cl₂ -> CF₂Cl• + •Cl
UV light

Question 10

What are the two propagation steps in the depletion of the ozone layer using chlorine radicals?

Answer 10

Step 1: Cl• + O₃ -> ClO• + O₂
Step 2: ClO• + O -> Cl• + O₂

Question 11

What are the two propagation steps in the depletion of the ozone layer using nitrogen oxide radicals?

Answer 11

Step 1: NO• + O₃ -> NO•₂ + O₂
Step 2: NO•₂ + O -> NO• + O₂

Question 12

What is the overall equation for the depletion of the ozone layer?

Answer 12

O₃ + O -> 2O₂