Organohalogen Compounds in the Environment (15.2)

Question 1

What is an organohalogen?

Answer 1

Molecules with at least one halogen atom connected to a carbon chain

Question 2

What are some uses for organohalogens?

Answer 2

-General solvents
-Dry cleaning solvents
-Refrigerants
-Pesticides

Question 3

What’s the layer above the troposphere called?

Answer 3

The stratosphere

Question 4

What is the outer edge of the stratosphere called?

Answer 4

Ozone layer

Question 5

What limits the amount of UV-B radiation reaching the earth?

Answer 5

Ozone

Question 6

What dangers come with the depletion of the ozone layer?

Answer 6

More UV-B radiation will reach the earth which increases the risks of skin cancer and genetic damage

Question 7

What happens to ozone in the stratosphere naturally?

Answer 7

Ozone is repeatedly formed and broken by UV radiation

Question 8

What is the equation for oxygen being broken down into oxygen radicals?

Answer 8

O2 –> 2O

Question 9

What is the reversible reaction between oxygen, oxygen radicals and ozone?

Answer 9

O2 + O –> O3

Question 10

What has upset the equilibrium of reactions in the ozone layer?

Answer 10

The use of CFC’s/Chlorofluorocarbons

Question 11

Why don’t CFC’s react when in the troposphere?

Answer 11

Because CFC bonds are stable in the troposphere

Question 12

Why do CFC’s break down in the ozone layer?

Answer 12

Because the UV radiation creates halogen radicals

Question 13

How do halogen/chlorine radicals upset the ozone layer’s equilibrium?

Answer 13

By catalysing the breakdown of ozone

Question 14

What can also cause ozone depletion?

Answer 14

Nitrogen oxides

Question 15

What are the propagation steps for nitrogen oxide radicals?

Answer 15

1.) NO * + O3 –> NO2 + O2
2.) NO2 + O –> NO* + O2

Question 16

How are nitrogen oxide radicals released?

Answer 16

-Through lightning strikes
-Aircraft travel in the stratosphere

Question 17

Why are C-Cl bonds the only ones that break in CFCs

Answer 17

Because C-Cl bonds have the lowest bond enthalpy

Question 18

What is the process where radiation initiates bond breakage?

Answer 18

Photodissociation

Question 19

What are the propagation steps for chlorine radicals reacting with ozone

Answer 19

1.) Cl* + O3 –> ClO* + O2
2.) ClO* + O –> Cl* + O2

Question 20

What is the overall equation for ozone breakdown?

Answer 20

O3 + O –> 2O2

Question 21

How do you create overall equations?

Answer 21

Remove spectating molecules/atoms (species that stay the same on the product and reactant sides)