S4 Air And Atmosphere Flashcards
What are 3 pollutants and what are their sources?
1) carbon monoxide - incomplete combustion of carbon-containing substances such as petrol
2) nitrogen oxides (NO,NO2) - lightning activity and internal combustion engines (oxygen and nitrogen react due to high temperatures)
3) sulfur dioxide - volcanic eruptions and combustion of fossil fuels
What is the effect of carbon monoxide?
Combines haemoglobin in blood to form carboxyhaemoglobin, which is extremely stable. It prevents haemoglobin from transporting oxygen to the rest of the body, may result in death
What are the effects of nitrogen oxides and sulfur oxide?(3)
1) irritate eyes and lungs and cause respiratory difficulties
2) high levels lead to inflammation of lungs (bronchitis)
3) formation of acid rain
Define air pollution.
It is the condition in which air contains a high concentration of certain chemicals that may harm living things or damage non living things.
How is acid rain formed?(2)
1) Sulfur dioxide dissolves in water to form sulfurous acid (H2SO3). In the presence of oxygen in the air, the acid is slowly oxidised to form sulfuric acid.
2) nitrogen is converted to nitric acid in the presence of oxygen and water.
What are the effects of acid rain?
1) acid rain reacts with metals and carbonates in marble and limestone. Metal bridges and stone buildings are damaged
2) reduce pH of natural water bodies to below 4, killing aquatic life
3) leaches important nutrients from soil and destroy plants
What are catalytic converters?
It is attached to the exhaust system of a car, and contains catalysts platinum and rhodium.
What are the 3 redox reactions that take place in a catalytic converters?
1) carbon monoxide is oxidised to carbon dioxide
2) oxides of nitrogen are reduced to nitrogen
3) unburnt hydrocarbons oxidise to carbon dioxide and water.
What are 2 measures used to reduce air pollution caused by motor vehicles?
1) use of alternative fuels such as hydrogen and methanol
2) development of electric-powered motor vehicles
What are flue gases?
They are waste gases such as sulfur dioxide formed when fossil fuels like coal undergo combustion.
How to minimise effects of sulfur dioxide pollution?
1) remove sulfur from fossil fuels before burning (expensive and difficult)
2) desulfurisation - remove sulfur dioxide from waste gases from burning.
What happens in desulfurisation?
As sulfur dioxide passes through the plant, it reacts with an aqueous suspension of calcium carbonate to form solid calcium sulfite and carbon dioxide. The calcium sulfite is further oxidised to calcium sulfate by atmospheric oxygen.
Why is Ozone layer important?
the ozone layer shields us from harmful ultraviolet radiation from the sun.
Why is the ozone depleting?
It is caused by chlorofluorocarbons(CFCs). CFCs are compounds containing carbon, fluorine and chlorine. In the presence of UV light, CFCs break down to form chlorine atoms that are very reactive. They react with ozone(O3) to form chlorine oxide and oxygen, destroying the ozone layer. If ozone depletion continues, more harmful UV radiation will reach the earth, causing skin cancer, genetic mutations, eye damage such as cataracts.
What are the 2 main processes that produce carbon dioxide?
1) respiration. Glucose is oxidised to form energy, carbon dioxide and water.
2) combustion of fuels such as methane forms carbon dioxide, water and energy.
