Chapter 15 - Haloalkanes (MODULE 4)

Question 1

how are haloalkanes named

Answer 1

add prefix of halide, in alphabetical order, in front of the longest chain

Question 2

What is a haloalkane

Answer 2

a compound containing carbon, hydrogen and at least one halogen

Question 3

What are species that donate a lone pair of electrons known as

Answer 3

nucleophiles

Question 4

What are some common examples of nucleophiles

Answer 4

hydroxide ions, water molecule, ammonia

Question 5

what is nucleophilic substitution in haloalkanes

Answer 5

when a nucleophile replaces the halogen in a haloalkane

Question 6

What happens during hydrolysis of a haloalkane

Answer 6

halogen in haloalkane is replaced by a hydroxide ion

Question 7

during hydrolysis, what happens to the carbon- halogen bond

Answer 7

undergoes heterolytic fission

Question 8

What product is formed when a haloalkane undergoes hydrolysis

Answer 8

alcohol

Question 9

what is done to speed up the hydrolysis reaction of haloalkanes

Answer 9

heated under reflux

Question 10

What does the rate of hydrolysis of haloalkanes depend on

Answer 10

the carbon halogen bond strength

Question 11

What is the order of bond strength, highest to lowest of:

C-F
C-Cl
C-Br
C-I

Answer 11

C-F strongest
C-Cl
C-Br
C-I weakest

Question 12

Why are fluoroalkanes relatively unreactive

Answer 12

large quantities of energy are needed to break the C-F bond

Question 13

how to the reaction speeds of iodoalkanes compare to chloroalkanes and bromoalkanes

Answer 13

iodoalkanes faster than bromoalkanes faster than chloroalkanes

Question 14

how would you measure the rate of hydrolysis of a primary haloalkane

Answer 14

react the haloalkane with aqueous silver nitrate, and measure the time taken for a precipitate to form

Question 15

How do the hydrolysis speeds of primary, secondary and tertiary haloalkanes compare

Answer 15

tertiary is fastest, then secondary then primary

Question 16

what are organohalogens

Answer 16

molecules with at least one halogen atom bonded to a carbon chain

Question 17

what is the ozone layer

Answer 17

a layer of attmosphere at the outer edge of stratosphere

Question 18

Why is the depletion of the ozone layer bad for organisms

Answer 18

increased amounts of UV-B radiation reach the earth, which causes sunburn and cancer

Question 19

What is the equilibrium reaction of the formation of ozone

Answer 19

O2 + O ⇌ O3

Question 20

What do CFCs stand for

Answer 20

chlorofluorocarbons

Question 21

What does HCFC stand for

Answer 21

hydro chloro fluoro carbons

Question 22

Why are CFCs and HCFCs quite stable

Answer 22

because of the strength of the carbon halogen bonds within their molecules

Question 23

What happens when CFCs reach the stratosphere

Answer 23

they begin to break down and form chlorine radicals, which catalyse the breakdown of the ozone layer

Question 24

What is the initiation step of the reaction of CF2Cl2 and ozone
- what catalyst is needed

Answer 24

CF2Cl2 -> CF2Cl* + Cl*
- UV

Question 25

What are the 2 propagation steps of the reaction of CF2Cl2 and ozone

Answer 25

Cl* + O3 -> ClO* + O2 ClO* + O -> Cl* + O2

Question 26

What is the overall equation for the breakdown of ozone due to CFCs or NO*

Answer 26

O3 + O -> 2O2

Question 27

Apart from CFCs, what is the other common radical that breaks down ozone

Answer 27

nitrogen oxide radicals

Question 28

What are the propagation steps for the breakdown of ozone due to nitrogen oxide

Answer 28

NO* + O3 -> NO2* + O2 NO2* + O -> NO* + O2

Question 29

What did the Montreal Protocol in 1987 introduce

Answer 29

steps for the complete removal of CFCs in all products unless there were no alternatives