Air Quality, Climate and Water Flashcards
Which gas is most present in clean, dry air?
nitrogen
What is the composition of clean, dry air?
78% nitrogen
20% oxygen
1% water vapour
0.97% argon (among other inert gases)
0.03% carbon dioxide and others
How is carbon dioxide mainly formed?
complete combustion of carbon-containing fuels
How is carbon monoxide formed?
incomplete combustion of carbon-containing fuels
How are particulates (soot) formed?
incomplete combustion of carbon-containing fuels
How is methane formed (2 ways) ?
decomposition of vegetation
waste gases from digestion in animals
How are oxides of nitrogen formed?
nitrogen and oxygen in the air react in the HIGH TEMPERATURES of car engines
fala high temperatures
nao fala heat
How is sulfur dioxide formed?
combustion of fossil fuels that contain sulfur compounds
What are common air pollutants?
carbon dioxide
carbon monoxide
soot/particulates
oxides of nitrogen
sulfur dioxide
methane
What is the negative effect of carbon dioxide?
increases global warming, leads to climate change
What is the negative effect of carbon monoxide?
toxic gas, binds to haemoglobin in your blood and reduces capacity to carry oxygen
What is the negative effect of soot/particulates?
increases risk of cancer
increases risk of respiratory problems
What are the negative effects of nitrogen oxides?
acid rain
photochemical smog
respiratory problems
What is the negative effect of methane?
increases global warming, leads to climate change
What is the negative effect of sulfur dioxide?
acid rain
What are strategies to reduce the effects of climate change?
planting trees
reducing livestock farming
less use of fossil fuels
more use of hydrogen
renewable energy
What are strategies to reduce the effects of acid rain?
catalytic converters in vehicles
using low-sulfur fuels
use of flue gas + calcium oxide for desulfurisation
What is an obligatory product of incomplete combustion?
water
What other products, besides water, can be formed from incomplete combustion?
soot, carbon monoxide, carbon dioxide
What is the general word equation for complete combustion?
hydrocarbon + oxygen -> carbon dioxide + water
Which two products are always formed from complete combustion?
carbon dioxide and water
What two ways do greenhouse gases (CO2 and methane) cause global warming?
they absorb, reflect and emit thermal energy
reduce the loss of thermal energy to space
How do oxides of nitrogen form in car engines?
nitrogen and oxygen in air react in the heat of a car engine
What happens to nitrogen oxides in a catalytic converter?
they are reduced
Define ‘photosynthesis’.
the process which uses energy from light to convert water and carbon dioxide into oxygen and glucose in the presence of chlorophyll
What is the word equation for photosynthesis?
carbon dioxide + water → glucose + oxygen
What is the symbol equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What are two tests to test the presence of water?
anhydrous cobalt (II) chloride
anhydrous copper (II) sulfate
What happens to anhydrous copper(II) sulfate when it is in contact with water?
it goes from white to blue
What happens to anhydrous cobalt (II) chloride when it is in contact with water?
it goes from blue to pink
How do you test for water purity?
boil water, if it boils at 100 degrees it is pure
freeze water, if it freezes at 0 degrees it is pure
Why is distilled water used in practical chemistry?
distilled water has less chemical impurities
What potentially harmful substances can be found in water from natural sources?
some metal compounds
some plastics
sewage
nitrates and phosphates
Which beneficial substances can be found in water from natural sources?
dissolved oxygen
some metal compounds
Why are some plastics in water from natural sources harmful?
harm aquatic life
Why is sewage in water from natural sources harmful?
has harmful microbes which can cause disease
Why are nitrates and phosphates in water from natural sources harmful?
cause deoxygenation of water, damages aquatic life
Why is dissolved oxygen in water from natural sources beneficial?
beneficial for aquatic life
Why are some metal compounds in water from natural sources beneficial?
provide essential minerals for life
What is the function of sedimentation and filtration in water treatment?
remove solids
What is the use of carbon in water treatment?
removes smells and tastes
What does chlorination do in water treatment?
kill microbes
equation for what happens in the catalytic converter
2CO + 2NO -> 2CO2 + N2
equation for formation of oxides of nitrogen
N2 + 2O2 -> 2NO2
how catalytic converter reduces emissions of of pollutantants
- carbon monoxide converted to carbon dioxide (2CO + O2 -> 2CO2)
- oxides of nitrogen are reduced to nitrogen
- hydrocarbons are burned to make water
- products: carbon dioxide, water, nitrogen
what is the pH of rain
5.6 (naturally acidic) as it mixes with solutes in the air
when CO2 and other solutes dissolve in rainwater, what is formed?
carbonic acid
formation of acid rain
- some fossil fuels contain sulphuric impurities
- when burnt sulfur react with oxygen, producing sulphuric dioxide
- sulphuric dioxide dissolves in rainwater to make sulphuric acids which form acid rain
problems with acid rain
- dissolve limestone (buildings)
- destroy vegetation
- kill water lief due to changing a lake, river, etc
- damage human skin
ammonium salts and nitrates are used as
fertilisers
Describe the use of NPK fertilisers
provide the elements nitrogen, phosphorus and potassium for improved plant growth
