Atmospheric Chemistry Flashcards
(28 cards)
how far is the atmosphere
extends about 100km
how far is thin air
6 km up the air is too thin to breath
what does the atmosphere consist of
mixture of gases
similar all over the earth due to mixing
1. caused by rotation of earth
2. heating of earth by sun
composition of earth
nitrogen oxygen carbon dioxide noble gases water pollutants
production of oxygen
- natural production
made by green plants using photosynthesis
6CO2 + 6H2O = C6H12O6 + 6O2 - industrial production
fractional distillation of liquid air
a) scrub air - remove water and dust
b) liquefy - compressing then cooling then releasing
c) separate - let liquid warm up gases will boil of when their boiling point is reached
boiling points
Bigger atoms (molecules) have higher boiling points due to bigger attraction between molecules caused by Van der Waal’s Forces
0C = K - 273
K = oC + 273
[ -273 0C = Absolute Zero]
uses of oxygen
- oxygen in hospitals
- cellular respiration
- combustion
- steel making
- in rockets
nitrogen
unreactive
needs lots of energy to break n triple bond n
lightning can provide this forming NO2
N2 + 2O2 = 2NO2
NO2 dissolves in rain to form nitrites and nitrates
H2O + 2NO2 = HNO2 + HNO3
HNO2 = nitrites HNO3 = nitrates
uses of nitrogen
- Haber process - making ammonia
- liquid nitrogen to freeze pizzas
- filling crisp packets - prevent crushing
nitrogen cycle
atmospheric nitrogen 78 % nitrification denitrifying bacteria nitrates in soil death and decay absorbed by plants plants death and decay animals eaten as food death and decay and excretion
noble gases
He - filing airships
Ar - filing light bulbs
Ne - neon light
inorganic carbon compound
co produced by incomplete combustion
co is a neutral oxide
no effect on universal indicator
types of oxide
Acidic
neutral
basic
types of oxide
Acidic
neutral
basic
CO2
PRODUCED
USED
produced - respiration, burning, rotting, fermentation
used in - photosynthesis, fire extinguishers, fizzy drinks
carbon dioxide is an acidic oxide
CO2 + H2O -> H2CO3
carbonic acid is a weak acid - it turns Universal Indicator yellow
carbon cycle
atmospheric CO2 0.03% plants photosynthesis animals eaten respiration respiration solution oceans death and decay fossil fuels carbonate rocks roasting limestone
greenhouse gases
CO2
CH4
CFCs
H2O
levels of CO2 are getting too high
due to increase in use of fossil fuels, rainforest burning, deforestation
CH4 from oil fields, rubbish dumps and cattle belching
more violent weather
rising sea levels
pollution
Addition of any damaging substance to the environment
atmospheric pollution example
Acid rain formation and effect
SULPHUR DIOXIDE S02 from- volcanoes fossil fuel combustion industry S + O2 = SO2
Acid rain has a pH of less than 4.5
SO2 dissolves in rainwater to form H2SO3 [sulphurous acid]
SO2(g) + H2O(l) = H2SO3(aq)
Sulphurous acid then reacts with O2 in air
H2SO3(aq) + ½ O2(g) = H2SO4(aq)
[sulphuric acid]
causes
- corrosion
- health effects
- death of animals
- death of plants
Nitrogen Dioxide NO2
N2 generally unreactive
N2(g) + O2(g) = 2 NO(g)
[nitrogen monoxide - colourless gas]
NO(g) + 1/2 O2(g) = NO2(g)
[nitrogen dioxide - brown gas]
2 NO2(g) + H2O(l) = HNO2(aq) + HNO3(aq)
Nitrous acid Nitric acid
Other Pollutants
Lead and lead compounds (Pb)
Replaced by Volatile Organic Chemicals [VOC’s] e.g. benzene
VOC + O2 + UV => O3 (poisonous)
CFCs
HCFCs
If we change a Cl in CCl4 for a F then we get CFCl3 a ChloroFluoroCarbon a CFC
HCFCs = HydroChloroFluoroCarbons
ozone layer
O3 formed in stratosphere 25 - 50 km up Absorbs harmful UV radiation from sun UV burns and causes cancer.
Formation of Ozone
O2 = (UV) O radical + O radical
oxygen splitting called photodissociation {breaking of a bond using light}
O radical + O2 = O3
Most of the oxygen radicals [atoms] formed in this way react with oxygen molecules to form ozone again.
In this way even more harmful UV is absorbed and ozone is not depleted
some ozone lost due to oxygen radicals react with ozone form oxygen
O radical + O3 = 2O2
