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Chem S4 > Air & Atmosphere > Flashcards

Air & Atmosphere Flashcards

1
Q

What is dry air

A

Air without the presence of water vapour

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2
Q

Is air mixture or compound

A

Air is a mixture that can be separated by physical means

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3
Q

What do you obtain from air

A

Nitrogen, Oxygen and Argon through fractional distillation of liquid air

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4
Q

What is argon used for

A

Maintaining inert atmosphere in filament lamps

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5
Q

Sources and uses of Nitrogen

A

Fractional distillation of liquid air, used in haber process

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6
Q

Sources and uses of Oxygen

A

Fractional distillation of liquid air, life sustaining processes like respiration

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7
Q

Sources and uses of Argon

A

Fractional distillation of liquid air, provide inert environment

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8
Q

Sources and uses of CO2

A

Waste gases in industrial processes, photosynthesis

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9
Q

Sources and uses of Water Vapour

A

Evaporation of water, essential to sustain plants and animals

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10
Q

Sources and uses of Hydrogen

A

Cracking of crude oil/electrolysis of water, rocket fuel, hydrogen powered cars

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11
Q

Sources and uses of Chlorine

A

Electrolysis of concentrated NaCl, bleach and disinfectant

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12
Q

Sources and uses of SO2

A

Combustion of sulfur-containing compounds, reducing agent and to preserve food

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13
Q

Sources and uses of Ammonia

A

Haber process, production of nitric acid and fertilizers in plants

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14
Q

How to remove acidic gases

A

Bubble through alkali

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15
Q

How to remove alkaline gases

A

Bubble through an acid

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16
Q

How to remove gaseous reducing agents

A

Pass the gas over heated copper (II) oxide

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17
Q

How to remove gaseous oxidising agents

A

Pass the gas over heated copper metal

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18
Q

How to remove water vapour

A
  1. Bubble through concentrated sulfuric acid
  2. Pass through calcium oxide
  3. Pass through fused calcium chloride
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19
Q

Which gases can be collected by displacement of water

A

Hydrogen, Carbon dioxide, Oxygen

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20
Q

Which gases can be collected by upwards delivery

A

Ammonia

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21
Q

Which gases can be collected by downwards delivery

A

Chlorine, sulfur dioxide

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22
Q

Which gases can be collected by gas syringe

A

All gases

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23
Q

What is an air pollutant

A

An air pollutant is a substance which is introduced to the air by human activity and has a harmful effect on the environment, including our health

24
Q

Is carbon dioxide an air pollutant

A

Yes and No. No cause it is already found in clean air but yes because levels of CO2 have increased and it is heating up Eartyh

25
Q

Is carbon dioxide an air pollutant

A

Yes and No. No cause it is already found in clean air but yes because levels of CO2 have increased and it is heating up Earth

26
Q

is rain, pH 6.5 acidic

A

No, normal rain is slightly acidic cause carbon dioxide forms a weak acid with water

27
Q

How is carbon monoxide formed

A

Incomplete combustion of carbon based fuels such as coal and hydrocarbons. Occurs in vehicles and coal-powered factories

28
Q

Why is carbon monoxide harmful

A

CO binds strongly with haemoglobin in our red blood cells preventing our body from transporting oxygen. Over time, this will cause breathing difficulties, fatigue and death

29
Q

How to reduce CO emissions

A
  1. Use cleaner fuels, lower occurrence of incomplete combustion 2. Install catalytic converter in vehicle exhausts
30
Q

How is SO2 formed

A

Combustion of fossil fuels containing sulfur impurities such as coal and hydrocarbons. Occurs in industrial areas

31
Q

How is SO2 formed

A

Combustion of fossil fuels containing sulfur impurities such as coal and hydrocarbons. Occurs in industrial areas

Also found naturally at volcanoes

32
Q

How is SO2 bad

A

Readily reacts with moisture in atmosphere to form acid rain which corrodes buildings, stonework, vegetation and marine life. Can also react with moisture in eyes and lungs to cause eye irritation and lung damage

33
Q

How to reduce SO2

A
  1. Use desulfurised fuels
  2. Flue gas desulfurisation, SO2 reacts with limestone
34
Q

How are oxides of nitrogen formed

A

Combution of nitrogen, and lightning

35
Q

How are oxides of nitrogen bad

A

Readily reacts with moisture in atmosphere to form acid rain, corroding buildings, stonework, vegetation and marine life

36
Q

How to reduce oxides of nitrogen

A

Install catalytic converter in vehicle exhausts

37
Q

Environmental issues of air pollution: Global Warming

A

Greenhouse gases, CH4 and CO2 trap heat. Human activities such as burning of fossil fuelds lead to increase of greenhouse gases causing global warming

38
Q

Problems of Global Warming

A
  1. Melting of polar ice caps resulting in rising sea levels and floods
  2. Drying up of water bodies
39
Q

Environmental issues of air pollution: Depletion of ozone layer

A

Earth surrounded by layer of Ozone, O3. Important role in reducing intensity of ultra-violet radiation from sun.

40
Q

Problems of depletion of ozone layer

A
  1. Without screening effect, overexposure to ultra-violet radiation on earth would occur, leading to skin cancer, genetic mutations and eye damage
  2. CFCs emit chlorine atoms in presence of ultra-violet light which reacts with ozone hence depleting it
41
Q

What is the carbon cycle

A

The carbon cycle is important in maintaining the level of carbon dioxide in our atmosphere, so as to allow respiration and prevent global warming

42
Q

How is carbon dioxide removed from atmosphere (include equation)

A

Photosynthesis, 6CO2 + 6H2O -> C6H12O6 + 6O2

43
Q

Respiration equation

A

C6H12O6 + 6O2 -> 6CO2 + 6H2O

44
Q

Main greenhouse gases

A

CO2, CH4, O3, CFCs, unburnt hydrocarbons

45
Q

What is flue gas desulfurisation

A

Flue gas desulfurisation is the process of removing sulfur dioxide from waste gases of factories in industrial areas through the use of limestone

46
Q

Process of flue gas desulfurisation

A
  1. Limestone thermally decomposes to form calcium oxide and CO2. CaCO3 -> CaO + CO2

2.Calcium oxide reacts with SO2 to form calcium sulfite.
CaO + SO2 -> CaSO3

  1. Calcium sulfite oxidises in air to form calcium sulfate. 2CaSO3 + O2 -> 2CaSO4
47
Q

Uses of calcium sulfate

A

Cement or hard casts

48
Q

Why is limestone used instead of calcium oxide directly

A

Limestone is abundant and hence cheaper

49
Q

What is a catalytic converter

A

A catalytic converter is a device fitted in motor exhausts to facilitate the removal of air pollutants by allowing various air pollutants to react with each other through a series of redox reactions, forming less harmful products

50
Q

Catalytic conversion of CO

A

CO -> CO2

51
Q

Catalytic conversion of oxides of nitrogen

A

NO/NO2 -> N2

52
Q

Catalytic conversion of CH4

A

CH4 -> CO2 + H2O

53
Q

Catalytic conversion of hydrocarbons

A

CxHy -> CO2 + H2O

54
Q

Why catalytic converters in car don’t need remove SO2

A

Vehicle exhaust fumes do not contain SO2 as petrol fuel is desulfurised

55
Q

Equation of reaction between CO and NO2

A

4CO + 2NO2 -> 4CO2 + N2

Chem S4 (3 decks)

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