Air & Water Flashcards

1
Q

What is coal gasification?

A

The process of producing syngas from coal, water, and oxygen

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2
Q

What is syngas?

A

A raw material that can be used as a fuel or to produce useful chemicals

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3
Q

Benefit of using hydrogen as a fuel

A

It is environmentally-friendly since it only releases H2O as a product

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4
Q

Source of hydrogen

A
  • steam reformation of methane

- cracking of hydrocarbons

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5
Q

Percentage of nitrogen in air:

A

79%

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6
Q

Percentage of oxygen in air

A

20%

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7
Q

Percentage of carbon dioxide in air:

A

0.3%

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8
Q

Results of fractional distillation of air:

A
  1. Oxygen
  2. Argon
  3. Nitrogen
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9
Q

Uses of oxygen

A
  • making steel
  • oxygen tents in hospitals
  • oxy-acetylene flames in welding
  • oxygen cylinders for divers/high-altitude mountaineers
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10
Q

Source of carbon monoxide

A

Incomplete combustion of compounds containing carbon

Includes: petrol, coal, oil, gas

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11
Q

Effect of carbon monoxide

A

Reduces the ability of blood to carry oxygen.

Instead of oxyhemoglobin, it becomes carboxyhaemoglobin.

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12
Q

Source of lead compounds:

A

Car exhausts. It is formed through the combustion of petrol containing lead.

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13
Q

Harmful effects of lead compounds

A

Causes lead poisoning, which may lead to brain damage

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14
Q

Sources of methane

A
  • bacterial decay of vegetable matter

- waste gases from digestion in animals

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15
Q

Harmful effects of methane

A

Greenhouse gas

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16
Q

Source of ozone

A

Photochemical reactions

17
Q

Harmful effects of ozone

A

reacts with unburned hydrocarbons to form photochemical smog, which causes respiration problems

18
Q

Source of unburned hydrocarbons

A
  • incomplete combustion of petrol in internal combustion engines of cars
  • leakage from petrol tanks in vehicles (petrol vaporises and escapes)
19
Q

Harmful effects of hydrocarbons

A

Some hydrocarbons are toxic and can disrupt healthy cell growth in small children

20
Q

Source of sulphur dioxide

A
  • burning of fossil fuels containing sulphur compounds

- volcanic eruptions

21
Q

Harmful effects of sulphur dioxide

A

Causes acid rain

22
Q

Source of nitrogen oxides

A
  • combustion of fuel in internal combustion engines at high temperatures
  • lightning activity
23
Q

Harmful effects of nitrogen oxides

A
  • acid rain

- catalyses the photochemical formation of ozone

24
Q

Effects of acid rain:

A
  • erosion of steel/concrete structures
  • increased soil acidity
  • lower pH levels in lakes/streams
  • aquatic life affected
25
Q

Uses of calcium carbonate

A
  • reduces acidity

- desulphurisation: removes SO2 in flue gas

26
Q

What does a catalytic converter do?

A

Redox reactions:

  • nitrogen oxide to nitrogen
  • carbon monoxide to CO2
  • unburned hydrocarbons to CO2 and H2O
27
Q

Examples of greenhouse gases and their sources:

A
  • CO2 from combustion of fossil fuels
  • methane from rotting vegetation
  • CFC from aerosol propellants/refrigerants
28
Q

Describe the greenhouse effect

A

Greenhouse gases absorb the heat energy radiated back from the earth’s surface so that the heat is retained. As a result, the surface temperature increases.

29
Q

Sources of CFC

A
  • aerosol propellants

- refrigerants

30
Q

Harmful effects of CFC

A
  1. The high-energy radiation breaks carbon’s bonds with chlorine
  2. Chlorine proceeds to bond with oxygen from the ozone layer, effectively destroying ozone molecules
31
Q

What does the ozone layer do?

A

Prevents high-energy UV radiation from penetrating to the earth’s surface

32
Q

Composition of natural water and their contents:

A
  • rain-water: made up of dissolved gases
  • rain-water (industrial areas): made up of dissolved pollutants
  • rain-water (becomes surface water): contains mineral salts, organic matter, etc
  • surface water (agricultural lands): contains nitrates and phosphates from fertilisers leached from the soil
33
Q

Effects of water pollutants:

A
  • metal poisoning
  • nitrates interfere with haemoglobin’a ability to carry oxygen
  • nitrates and phosphates cause eutrophication
34
Q

Uses of water:

A
  • food/car manufacturing: washing and cleaning
  • steel mills+power stations: cooling purposes
  • soft drinks: food processing
35
Q

Describe the water purification process:

A
  1. Coagulation
  2. Sedimentation
  3. Filtration
  4. Chlorination
36
Q

Why is alum used in water purification processes?

A

Coagulating small particles to make big solid lumps

37
Q

Why is lime used in water purification processes?

A

To neutralise acidic impurities

38
Q

Products of complete combustion of fossil fuels

A

CO2/CO and H2O