Alkanes

Question 1

What is the initiation stage of reacting chlorine with methane

Answer 1

Essential condition = UV light to break Cl-Cl bond, as it is a weak bond
Cl2=2Cl:
: represents a single electron, meant to be one dot
Bond has broken in homolytic fission, each atom gets one electron from the covalent bond

Question 2

Define free radical

Answer 2

A reactive species which possesses an unpaired electron

Question 3

Give the overall equation of the formation of chloromethane

Answer 3

CH4+ Cl2= CH3Cl+ HCl
Methane gas reacts with chlorine gas to form chloromethane and hydrochloric acid

Question 4

Describe stage 1 of propagation for the formation of chloromethane

Answer 4

Chlorine free radicals are very reactive and will remove a H from the methane leaving a methyl free radical and hydrochloric acid
CH4+ Cl:=HCl + :CH3

Question 5

Describe stage 2 of propagation for the formation of chloromethane

Answer 5

Methyl free radical reacts with a Cl2 molecule to produce the main product and another Cl free radical
;CH3+ Cl2=CH3Cl+ Cl
When the Cl free radical is regenerated it reacts with several more alkanes in a chain reaction

Question 6

Describe termination stage of forming chloromethane

Answer 6

Collision of two free radicals does not generate further free radicals,chain is terminated
:CH3 + :Cl= CH3Cl
:Cl+:Cl= Cl2
:CH3 + :CH3 = CH3CH3