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TSHALTAIAGFFA.IIAO.NCBDTCI.IIASOLAL,BAB,CAS,ATDOD.IIASOTBLBOBAOW.IITSOTEOAE.TSTAS-TTAHSLAASFATWCDTTNTD,IIAHRN.RH.IIHAYRTW.TIHTFMCTAC.CATHCATYOP.TINJTEOAR,NIFOCI.TITTOTJ.TESN. > Chem Air > Flashcards

Chem Air Flashcards

1
Q

What is the composition of air?

A 
Nitrogen 78% 
Oxygen 21%
CO2 0.03%
Water vapour 0-5%
Noble gases >1%
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2
Q

What does the fractional distillation of liquid air aim to get

A

Nitrogen and oxygen

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3
Q

Steps of fractional distillation of air (2)

A
  1. Air is cooled and compressed into a liquid
  2. It is then soersted into its constituents via fractional distillation, lowest bp distills first (N2)
    Boiling points:
    - nitrogen: -196
    - argon: -186
    - oxygen: -183
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4
Q

Finding % of oxygen in air (copper)

A

Known amt of air is passed back and forth over heated copper -> copper II oxide, o2 decrease -> air in syringe decr

Calc:
Vol of o2= initial vol-final vol
%=vol of o2/initial vol

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5
Q

Definition of air pollution

A

Air pollution is the condition in which air contains a high concentration of certain chemicals that may harm living things or damage non-living things

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6
Q

3 common air pollutants

A

1 carbon monoxide CO
2 oxides of nitrogen NOx: NO, NO2
3 sulfur dioxide SO2

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7
Q

Sources of carbon monoxide

A
  • incomplete combustion of carboncontaining fuels

- incomplete combustion of petrol in car engines

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8
Q

How are oxides of nitrogen produced 2

A
  1. Car engines or factories
    Temp is very high,
    N2 + O2 in air = 2NO
    More oxygen: 2NO + O2 = 2NO2
  2. Lightning strikes
    Heat energy released by lightning
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9
Q

How do oxides of nitrogen form acid rain

A

Oxides of N and oxygen and water
4NO2 + O2 + H2O -> 4HNO3
Acid rain

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10
Q

How is Sulfur dioxide produced 2

A
  1. Combustion of sulfurcontaining fossil fuels (major source)
    Eg. Coal, crude oil, natural gas -> sulfur as impurities (higher in coal)
    S + O2 =heat= SO2
  2. Volcanic eruptions
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11
Q

How does sulfur dioxide result in acid rain

A

Sulfur dioxide and oxygen in air dissolves in rainwater

2SO2 + O2 + 2H2O = 2H2SO4

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12
Q

What are some other air pollutants 4

A
  • unburnt hydrocarbons
  • methane CH4
  • lead Pb
  • ozone O3
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13
Q

How are unburnt hydrocarbons and lead produced

A

Unburnt hydrocarbons and lead : car exhaust and chemical plants

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14
Q

How is methan producedb

A
  • Bacteria decay of dead plant and dead animal matter, decay of rubbish
  • a greenhouse gas -> polar ice caps melt: flooding & drastic weather changes
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15
Q

How is ozone produced

A

NO2 and unburnt hydrocarbons in presence of sunlight

At low altitudes it causes pollution problems, breathing difficulties, and photochemical smog

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16
Q

Effect of carbon monoxide on environment

A

Binds strongly with haemoglobin to form carboxyhaemoglobin, which is very stable and hard to reverse
Cannot transport O2 to the rest of the body -> headaches fatigue breathing difficukties and death

17
Q

Effects of oxides of nitrogen and sulfur dioxide on the environment (acid rain)

A 
Acid rain -> they dissolve in rainwater 
Sulfur dioxide with oxygen and water to sulfuric acid
2SO2 + O2 = 2SO3 
SO3 + H2O =H2SO4 
Nitrogen dioxide to nitric acid 
4NO2 + 2H2O + O2 = 4HNO3
18
Q

Effects of Acid rain

A

pH of 4 or less

  • Metal bridges and stone buildings are corroded
  • Reduce pH of natural water bodies, destroy fish and plants
  • Leaches impt nutrients from soil, destroys plants and crops. Plant growth stunted
  • Irritate eyes, breathing difficulties, inflammation of lungs
19
Q

Impacts of unburnt hydrocarbons

A 
Causes cancer (carcinogenic) 
Reacts with nitrogen oxides to form ozone at low altitudes
20
Q

Impacts of methane on environment

A

CH4

Greenhouse gas

21
Q

Impacts of ozone on environment

A

(At low altitudes)
Forms photochemical smog - irritates eyes lungs, breathing difficulties
Damages crops (less O2)

22
Q

Increase of 1 in pH =

A

10fold in acidity

23
Q

How to reduce effects of acid rain 3

A

1 Liming - Powdered linestone CaCO3 : neutralise (temp and ex)
2 catalytic converters (vehicles)
3 flue gas desulfurisation (BGD plant)

24
Q

Catalytic converters

A

Catalysts: platinum and rhodium

Redox reactions
1 carbon monoxide oxidised carbon dioxide
2 oxides of nitrogen reduced nitrogen
3 unburnt hydrocarbons oxidised carbon dioxide and steam

25
Q

Flue gas desulfurisation

A
  1. Remove sulfur from fossil fiels before burning (ex, difficult)
  2. Remove sulfur dioxide from waste gases (flue gases) -> desulfurisation (cheaper)

Flue gas reacts with an aqueous suspension of moist limestone (calcium carbonate) or moist lime (calcium oxide) = solid calcium sulfite + CO2 gas
Calcium sulfite oxidised calcium sulfate (by atmospheric O2)

26
Q

Depletion of Ozone layer O3

A

Photochemical reaction between O2 and O in atmosphere

Advantage: at high altitudes (stratosphere), a shield, filters harmful ultraviolet radiation from sun

UV rad -> skin cancer, genetic muration, eye damage, harm marine life

27
Q

What is causing the depletion of ozone in the stratosphere?

A

Chlorofluorocarbons CFCs
1 carbon
2 fluorine
3 chlorine

Are very stable, remain in atmos for very long, slowly diffuse and react with ozone, destroying layer -> more UV

28
Q

Solution for ozone depletion

A

Ban use of CfCs but stuffs still there for very long

29
Q

Control of air pollution singapore

A

1 no open fires for disposal of domestic and industrial watse
2 introducing unleaded petrol and phasing out leaded petrol
3 reducing allowed lvl of sulfur in diesel
4 catalytic converters in petrol vehicles

30
Q

Reducing air pollution by motor vehicles 3

A

1 New materials like lightweight alloys to make car bodies -> lighter = less fuel
2 alternative clean fuels (methanol, hydrongen) -> products of combustion of these are harmless
3 dev of electric vehicles -> reduce exhaust

31
Q

Greenhouse effect

A

Rate of removal of atmospheric CO2 must be balanced by the rate of return of CO2 to atmosphere

Carbon cycle

32
Q

Greenhouse effect- return carbon 3

A

1 respiration: glucose -> CO2 + water
2 combustion of most fuels -> CO2 + water
3 decay and bacterial decomp -> breakdown of carbon compounds in them

33
Q

Greenhouse effect remove CO2 2

A

1 photosynthesis: CO2 + water -> glucose + O2
2 ocean uptake: dissolved CO2 used by plants and organisms. Most converted to calcium carbonaye (limsetone) : shells and skeletons -> linsteone

34
Q

Greenhouse gases

A

Gases that trap radiation -> absorbs radiation, less amt of heat energy into space

CH4 and Nitrous oxide -> stronger infrared absorbers than CO2
Water vapour as well

35
Q

Global warming

A

The incr in temp due to build up of grenhouse gases
Human acticities -> burning of fossil fuels, large scale cutting down forests -> rapid build up of gases
More return than removal

36
Q

Consequences of global warming 4

A

1 more unusual weather conditions
2 less crop yield (vegetation->deserts)
3 melting of ice -> ocean lvl rise, flood low lying areas
4 Rapid evap of water: CO2 from water in oceans to atmos

TSHALTAIAGFFA.IIAO.NCBDTCI.IIASOLAL,BAB,CAS,ATDOD.IIASOTBLBOBAOW.IITSOTEOAE.TSTAS-TTAHSLAASFATWCDTTNTD,IIAHRN.RH.IIHAYRTW.TIHTFMCTAC.CATHCATYOP.TINJTEOAR,NIFOCI.TITTOTJ.TESN. (28 decks)

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