Air & Water

Question 1

What is coal gasification?

Answer 1

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

Question 2

What is syngas?

Answer 2

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

Question 3

Benefit of using hydrogen as a fuel

Answer 3

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

Question 4

Source of hydrogen

Answer 4

• steam reformation of methane

- cracking of hydrocarbons

Question 5

Percentage of nitrogen in air:

Answer 5

79%

Question 6

Percentage of oxygen in air

Answer 6

20%

Question 7

Percentage of carbon dioxide in air:

Answer 7

0.3%

Question 8

Results of fractional distillation of air:

Answer 8

1. Oxygen
2. Argon
3. Nitrogen

Question 9

Uses of oxygen

Answer 9

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

Question 10

Source of carbon monoxide

Answer 10

Incomplete combustion of compounds containing carbon

Includes: petrol, coal, oil, gas

Question 11

Effect of carbon monoxide

Answer 11

Reduces the ability of blood to carry oxygen.

Instead of oxyhemoglobin, it becomes carboxyhaemoglobin.

Question 12

Source of lead compounds:

Answer 12

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

Question 13

Harmful effects of lead compounds

Answer 13

Causes lead poisoning, which may lead to brain damage

Question 14

Sources of methane

Answer 14

• bacterial decay of vegetable matter

- waste gases from digestion in animals

Question 15

Harmful effects of methane

Answer 15

Greenhouse gas

Question 16

Source of ozone

Answer 16

Photochemical reactions

Question 17

Harmful effects of ozone

Answer 17

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

Question 18

Source of unburned hydrocarbons

Answer 18

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

Question 19

Harmful effects of hydrocarbons

Answer 19

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

Question 20

Source of sulphur dioxide

Answer 20

• burning of fossil fuels containing sulphur compounds

- volcanic eruptions

Question 21

Harmful effects of sulphur dioxide

Answer 21

Causes acid rain

Question 22

Source of nitrogen oxides

Answer 22

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

Question 23

Harmful effects of nitrogen oxides

Answer 23

• acid rain

- catalyses the photochemical formation of ozone

Question 24

Effects of acid rain:

Answer 24

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

Question 25

Uses of calcium carbonate

Answer 25

- reduces acidity | - desulphurisation: removes SO2 in flue gas

Question 26

What does a catalytic converter do?

Answer 26

Redox reactions: - nitrogen oxide to nitrogen - carbon monoxide to CO2 - unburned hydrocarbons to CO2 and H2O

Question 27

Examples of greenhouse gases and their sources:

Answer 27

- CO2 from combustion of fossil fuels - methane from rotting vegetation - CFC from aerosol propellants/refrigerants

Question 28

Describe the greenhouse effect

Answer 28

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.

Question 29

Sources of CFC

Answer 29

- aerosol propellants | - refrigerants

Question 30

Harmful effects of CFC

Answer 30

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

Question 31

What does the ozone layer do?

Answer 31

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

Question 32

Composition of natural water and their contents:

Answer 32

- 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

Question 33

Effects of water pollutants:

Answer 33

- metal poisoning - nitrates interfere with haemoglobin'a ability to carry oxygen - nitrates and phosphates cause eutrophication

Question 34

Uses of water:

Answer 34

- food/car manufacturing: washing and cleaning - steel mills+power stations: cooling purposes - soft drinks: food processing

Question 35

Describe the water purification process:

Answer 35

1. Coagulation 2. Sedimentation 3. Filtration 4. Chlorination

Question 36

Why is alum used in water purification processes?

Answer 36

Coagulating small particles to make big solid lumps

Question 37

Why is lime used in water purification processes?

Answer 37

To neutralise acidic impurities

Question 38

Products of complete combustion of fossil fuels

Answer 38

CO2/CO and H2O