chpt 22 maintaining air quality

Question 1

What are some air pollutants ?

Answer 1

1.carbon monoxide
incomplete combustion of carbon containing materials eg hydrocarbons
toxic and binds irreversibly to haemoglobin in bloof
2. sulfur dioxide
volcanic eruption
acid rain corrosion
3. oxides of nitrogen
burning of fuels a HIGH temperatures eg in combustion engine of vehicles
acid rain corrosion
4. methane
common natural gas
greenhouse gas
5. unburnt hydrocarbons
incomplete combustion
eye and respiratory tract infections
6. ozone
rxn of hydrocarbons and nitrogen oxides in presence of sunlight at lower atmospheres
respiratory tract infections

Question 2

What causes the depletion of the ozone layer ?

Answer 2

1. ozone absorbs harmful UV rays and radiation
2. CFCs are harmless to animals and humans but as they rise up to higher atmosphere, decomposed by sunlight to produce chlorine atoms
3. chlorine atoms destroy ozone molecules and allows harmful sunlight to pass through
4. increase in skin cancer, eye infections

Question 3

What are the methods to reduce air pollution ?

Answer 3

1. Flue gas desulfurisation
2. catalytic converters

Question 4

How does flue gas desulfurisation work ?

Answer 4

1. main pollutant of sulfur dioxide comes from power stations
2. removal of sulfur dioxide from flue (waste) gases
3. calcium carbonate slurry sprayed through flue gas
4. forms calcium sulfate and carbon dioxide (less harmful)

Question 5

How do catalytic converters work ?

Answer 5

1. converters contain ceramic material coated with platinum catalysts
2. catalysts arranged in honey comb structures to maximise surface area to vol ratio
3. harmful pollutants converted into less harmful substances
4. does not prevent pollution, but reduces it (not a long term plan)
5. 2co (g) -> co2 (g)
6. nitrogen oxides -> nitrogen gas
7. unburnt hydrocarbons burnt to produce co2 and water vapour