Clean Air

Question 1

What affects the level of gases in the air?

Answer 1

1. Combustion of fossil fuels - increases the level of carbon dioxide and decreases the level of oxygen.
2. Respiration by plants and animals - increases level of carbon dioxide and decreases the level of oxygen
3. Photosynthesis by plants - decrease the level of carbon dioxide and increases the level of oxygen.

Question 2

What is the word equation for respiration?

Answer 2

Oxygen + glucose = carbon dioxide + water

Question 3

What is the word equation for photosynthesis?

Answer 3

Carbon Dioxide + water = oxygen + glucose.

Question 4

The level of carbon dioxide has increased slightly over the last few hundred years - why?

Answer 4

Deforestation - less photosynthesis.

Increased population and increased use of fossil fuels for energy.

Question 5

Name the main atmospheric pollutants.

Answer 5

Carbon Monoxide - poisonous gas formed by incomplete combustion of petrol and diesel.

Sulphur Dioxide - acid rain formed when the sulphur impurities in fossil fuels burn.

Oxides of nitrogen - photochemical smog acid rain formed by reaction of nitrogen and oxygen at high temperatures ( internal combustion engines in vehicles)

Question 6

What are some mechanisms for reducing pollution ?

Answer 6

Cars are fitted with catalytic converters containing the catalyst Rhodium - reduces the levels of carbon monoxide and oxides of nitrogen.

Carbon monoxide is converted to carbon dioxide
Oxides of nitrogen are converted to nitrogen.

Carbon monoxide + nitrogen monoxide = carbon dioxide + nitrogen

Question 7

What are the gases in clean air?

Answer 7

Oxygen - 21%
Nitrogen- 78% 
Remaining 1 % is made up of: 
Carbon Dioxide - 0.035%
Noble gases - argon, neon, krypton and xenon.

Water vapour content does vary.