Air (D) Flashcards
State the composition of air
- Air is a mixture of different gases:
- 78% nitrogen
- 21% oxygen
- 1% noble gases (mainly argon)
- 0.04% carbon dioxide
State the Sources of Sulfur Dioxide
- combustion of fossil fuels such as petrol and natural gas
- volcanic eruptions
- Note: sulfur present in the fossil fuels reacts with oxygen to form SO2
- equation: S + O2 → SO2
State the Sources of Oxides of Nitrogen
- Combustion of nitrogen and oxygen from air in the internal combustion engines of vehicles at high temperature.
- Lightning activities (where nitrogen and oxygen in the air react to form oxides of nitrogen)
- *N2(g) + O2(g) → 2NO(g)
- 2NO(g) + O2(g) → 2NO2(g)*
State the Sources of Carbon Monoxide
Incomplete combustion of carbon-containing fuels such as charcoal, wood, petrol.
State the Sources of Methane
- anaerobic (in the absence of oxygen) bacterial decay of organic substances
- waste gases from cattle
State the Sources of Unburnt Hydrocarbons
unburnt fuels in internal combustion engines of vehicles
- Lightning activities
- from reaction of unburnt hydrocarbons and nitrogen oxides in the presence of sunlight in the lower atmosphere.
- from reaction between oxygen molecules and sunlight in the upper atmosphere
What does catalytic converters do?
- oxidise CO into less harmful CO2
- reduce NO / NO2 to harmless nitrogen gas (N2).
- With platinum catalysts
Why is the catalytic converter still unable to remove all pollutants?
- CO2 produced is a greenhouse gas that causes global warming
- Catalytic converters reduce air pollution (original pollutants from the engines are more harmful than CO2). But catalytic converters cannot eliminate pollution.
How does photosynthesis and respiration regulate the amount of CO2 in atmosphere?
The amount of CO2 released into the atmosphere through respiration is the same as the amount of CO2 absorbed from the atmosphere through photosynthesis
Why can’t we planting more trees decrease amount of CO2 in air?
Human activities such as burning / combustion of fossil fuels are releasing more carbon dioxide at a higher rate compared to the amount of carbon dioxide that can be absorbed by planting more trees via photosynthesis.
State processes and equations that add and reduce CO2 in atmosphere
-
Combustion (add CO2 to atmosphere)
- CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g)
-
Respiration (add CO2 to atmosphere)
- C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H20 (l)
- Decomposition (add CO2 to atmosphere)
-
Photosynthesis (remove CO2 from atmosphere)
- 6CO2 (g) + 6H20 (l) → C6H12O6 (aq) + 6O2 (g)
Harmful Effects of carbon monoxide
- Carbon monoxide is a toxic gas and causes death.
- It combines with haemoglobin in red blood cells and lower the ability of haemoglobin to transport oxygen to the rest of the body.
Harmful effects of Sulfur Dioxide and Nitrogen Monoxide
- The gas causes breathing difficulties in humans and animals and leads to inflammation of the lungs
How is acid rain formed from Nitrogen Monoxide and Sulfur Dioxide?
- SO2(g) + H2O(l) → H2SO3(aq)
- 2H2SO3(aq) + O2(g) → 2H2SO4(aq)
- 4NO2(g) + O2(g) + 2H2O(l)→4HNO3(aq)
