10. air Flashcards
composition of air
- 78% nitrogen
- 21% oxygen
- 0.03% carbon dioxide
- <1% other gases (group 0 noble gases)
common atmospheric pollutants
- carbon monoxide
- nitrogen monoxide + nitrogen dioxide
- sulfur dioxide
- methane gas
- unburnt hydrocarbons
- carbon dioxide
carbon monoxide:
source
- incomplete combustion of carbon containing fuels
carbon monoxide:
effects on humans
- toxic to humans
- binds to haemoglobin in RBCs to form carboxyhaemoglobin
- irreversible reaction, reduces ability of RBCs to transport oxygen
- death
carbon monoxide:
solutions
- removed by reactions in catalytic converters in vehicles
- CO + O2 = CO2
nitrogen monoxide + nitrogen dioxide:
source
- lightning activities
- in internal combustion engines
- high temperature causes nitrogen and oxygen in the atmosphere to react
- nitrogen monoxide can oxidise easily to form nitrogen dioxide
nitrogen monoxide + nitrogen dioxide:
effects on environment
- nitrogen monoxide: neutral
- nitrogen dioxide: acidic gas
- dissolves in rainwater to form nitrous acid, oxidised to form nitric acid
- acid rain
impacts of acid rain
- corrodes buildings made of cement, reactive metals and limestone
- decreases pH in soils, unsuitable for growing crops, reducing crop yield
- may fall into rivers and lakes, decreasing pH of water and affecting plants + marine life
nitrogen monoxide + nitrogen dioxide:
effects on humans
- poisonous choking gas that irritates and attacks the lungs
- respiration problems
nitrogen monoxide + nitrogen dioxide:
solutions
- removed by reactions in catalytic converters in internal combustion engines
- decomposes in a redox reaction to form N2 and O2
- NO can react with CO to form CO2 and H2O
sulfur dioxide:
source
- volcanic eruptions
- incomplete combustion of fossil fuels in internal combustion engines
sulfur dioxide:
effects on environments
- acidic oxide
- dissolves in water to form sulfurous acid, which oxidises to form sulfuric acid
- acid rain
impacts of acid rain
- corrodes buildings made of cement, reactive metals and limestone
- decreases pH of soil, unsuitable for growing crops, reducing crop yield
- may fall into rivers or lakes, affecting pH of water and plant/marine life
sulfur dioxide:
effects on humans
- poisonous choking gas that irritates and attacks the lungs
- respiratory problems
sulfur dioxide:
solutions
- removed in flue glue desulfurisation to reduce liberation of sulfur dioxide gas
- flue glue: waste gas from combustion of fossil fuels
- sulfur dioxide + water = sulfurous acid
- moist calcium carbonate + sulfurous acid = calcium sulfite + carbon dioxide + water
- calcium sulfite + oxygen = calcium sulfate
methane gas:
effects on environment
- greenhouse gas
- traps infrared radiation, contributes to global warming
impacts of global warming
- melting of large quantities of ice in the north and south pole, sea level rise, flooding in low lying countries
- areas of land with vegetation become deserts, reducing crop yield
- high temperatures drive out carbon dioxide from the oceans, (ghg) increased concentration in atmosphere, vicious cycle
unburnt hydrocarbons:
source
- from the incomplete combustion of hydrogen containing substances in internal combustion engines
unburnt hydrocarbons:
effects on environment/humans
- results in photochemical reactions which produce ozone
- difficulty breathing
unburnt hydrocarbons:
solutions
- removed by reactions in catalytic converters in vehicles
carbon dioxide
- continuously produced and removed
- produced by: respiration, combustion
- removed by: photosynthesis
- maintained by the carbon cycle
impacts of carbon dioxide
- green house has
- traps infrared radiation, results in global warming
- impacts of global warming (refer to methane gas)
ozone
- ozone layer acts as a filter, prevents excess UV radiation from the sun from reaching the earth’s surface
depletion of ozone layer
- CFCs (chlorofluorocarbons) are used as propellants in aerosol sprays, and coolants in fridges/air cons
- usually unreactive at sea level
- when they move up to the stratosphere, decomposes under strong UV radiation to form chlorine atoms
effect of chlorine atoms
- chlorine atoms react with ozone layer to form oxygen molecules, creating holes in the ozone
- chlorine atoms are regenerated, process is capable of occurring repeatedly
equation
Cl + O3 = ClO + O2
ClO + O3 = Cl + 2O2
impacts of depletion of ozone layer
- depletion of ozone layer allows excess UV radiation from the sun to reach the surface of the earth
- drastic increase in skin cancer, genetic mutations and eye damage (cataracts)
