OZ 4-How Ozone Is Formed

Question 1

Define heterolytic fission

Answer 1

When a bond breaks and both electrons go to 1 atom

Question 2

Define homolytic fission

Answer 2

When a bond breaks and 1 electron goes to each atom

Question 3

What is formed from homolytic fission?

Answer 3

Radicals

Question 4

Is the splitting of HCl an example of homolytic or heterolytic fission?

Answer 4

Heterolytic, as atoms have different electronegativity

Question 5

What is a radical?

Answer 5

-a species with an unpaired electron

Question 6

Name the 3 steps in Free Radical Subsitition

Answer 6

1. Initiation
2. Propagation
3. Termination

Question 7

What occurs in Initiation of Free Radical Substitution?

Answer 7

• when radical are formed from homolytic fission

- always endothermic, as a bond is being broken

Question 8

What are the conditions for Free Radical Substitution?

Answer 8

• UV light

Question 9

What occurs in Propagation of Free Radical Substitution?

Answer 9

• when molecule and radical react to form a new molecule/radical pair
• a bond is broken and formed, so not endo or exothermic

Question 10

What occurs in Termination of Free Radical Substitution?

Answer 10

• when 2 radicals react to form 1 molecule

- a bond is formed, so is exothermic

Question 11

What do half arrows represent in Free Radical Substitution mechanism?

Answer 11

Movement of 1 electron

Question 12

What are the 3 ways in which oxygen radicals react with substances in the atmosphere? (Give equations)

Answer 12

1. O. + O2 O3 (produces ozone)
2. O. + O. O2 (reforms oxygen)
3. O. + O3 2O2 (decomposes ozone)