Free Radical Substitution Flashcards
What is a photochemical reaction
One which involves UV light
What is homolytic fission
The process of UV light providing the energy to break a covalent bond equally to form 2 free radicals
What are the 3 stages of a free radical substitution reaction
Initiation, propagation, termination
What type of reaction occurs in the propagation stage
A chain reaction
On an atomic level, what happens in the propagation stage
A hydrogen molecule is substituted by a free radical (probably chlorine)
What will be produced if chlorine is in excess
Chloromethane, dichloromethane, trichloroethane, tetrachloromethane
What will be the main product if methane is in excess
Chloromethane
What are CFCs
Chlorofluorocarbons
What is a safer alternate to CFCs
HFCs
How do the Cl free radicals form, give an equation for this reaction
UV breaks the Cl-Cl bond in the CFCs
CCL3F —> CCl2F + :Cl
Give the equation for the natural formation of ozone
O2 + :O —> O3
What is the role of the chlorine free radical
Acts as a catalyst to react with ozone
Give 2 equations to show the chlorine free radical acting as a catalyst as it reacts with ozone
:Cl + O3 —> :ClO + O2
:ClO + O3 —> :CL +2O2
What is the overall equation for the free radiation reaction of ozone
2O3 —> 3O2
