Free radical subsitution

Question 1

What are radicals

Answer 1

Atoms with an unpaired electron on the outer shell. This makes them very reactive

Question 2

How do we free Free radicals

Answer 2

We draw them with an . on the end to show the electron

Question 3

Initiation

Answer 3

UV breaks first halogen molecule into free radicals
e.g F2 -> F* + F*

Question 4

Propagation

Answer 4

Halogen radicals react with alkanes in a chin reaction where the halogen radical acts as a catalyst . This has two steps

Question 5

Propagation example

Answer 5

e.g CH4 ~> CH3Cl
1) CH4 + Cl* ~> *CH3 + HCl
2) CH3 + CL2 ~> CH3Cl + Cl

Question 6

Termination

Answer 6

When two free radicals meet they reaction to form a new molecule. This frees radicals and stops the chain reaction , But radicals far more likely to meet a molecule than a radicals

Question 7

Termination e.g
CH4 -> CH3Cl

Answer 7

Radicals involved in this reaction are
CH3 and Cl
1) Cl* + Cl* ~> Cl2
2) *CH3 + *CH3 ~> C2H6
3) CH3 + Cl -> CH3Cl

Question 8

Heterolytic fission

Answer 8

Both electrons go to the same atom making a X+ and Y-

Question 9

Both electrons go different ways making a X + Y

Answer 9

Homolytic fission