Atmosphere And Environment

Question 1

Composition of air

Answer 1

79 % nitrogen
20 % oxygen
0.97 % noble gases
0.03 % carbon dioxide

Question 2

Where is carbon monoxide produced?

Answer 2

Incomplete combustion of carbon-containing substances

Question 3

How is CO toxic?

Answer 3

The gas binds with haemoglobin in blood to form carboxyhaemoglobin, which deprives cells of oxygen

Can lead to headaches, fatigue and death

Question 4

Where do oxides of nitrogen come from?

Answer 4

Formed at high temperatures in combustion engines
Or lightning

High temperatures encourage nitrogen and oxygen to react

Question 5

Effects of oxides of nitrogen

Answer 5

Because they are acidic in nature, they cause acid rain when dissolved in water

Gas can irritate lung tissue and eyes

Question 6

How is sulfur dioxide formed?

Answer 6

Volcanic eruptions and burning of fossil fuels (presence of sulfur in fuels)

Question 7

Effects of sulfur dioxide

Answer 7

Acidic oxide that dissolves in water to form acid rain

Like oxides of nitrogen, inhaling sulfur dioxide causes respiratory problems and irritates the eyes

Question 8

How are unburnt hydrocarbons formed?

Answer 8

Incomplete combustion of fuels

Question 9

Effects of unburnt hydrocarbons

Answer 9

Breathing in these gases can cause cancer

Question 10

How is ozone produced?

Answer 10

Ozone is produced when oxides of nitrogen react with unburnt hydrocarbons in the presence of sunlight.

Question 11

Effects of ozone

Answer 11

At ground level, ozone is a pollutant which can cause respiratory problems

Question 12

How is acid rain formed?

Answer 12

Carbon dioxide forms carbonic acid when dissolved in rainwater in un polluted areas

In polluted areas, rainwater is more acidic due to formation of string acids in rainwater. Eg nitric acid, nitrous acid and sulfurous acid

Question 13

What are catalytic converters used for?

Answer 13

Catalytic converters are installed in car exhaust systems to reduce emissions of CO, oxides of nitrogen and unburnt hydrocarbons.

These substances undergo redox reactions in the presence of platinum and rhodium catalysts to from substances that are less harmful

Question 14

What are the chemical reactions that take place in catalytic converters?

Answer 14

Carbon monoxide is oxidised to form carbon dioxide

Oxides of nitrogen + CO -> nitrogen + carbon dioxide

Unburnt hydrocarbons are further oxidised to form carbon dioxide and water

Question 15

What is flue gas desulfurization?

Answer 15

Process in which sulfur dioxide is removed from waste gases emitted during industrial processes

Involves passing the waste gases through calcium carbonate or calcium oxide (acidic oxides react with basic substances)

Question 16

Sulfite VS sulfate

Answer 16

Sulfite: SO3 2-
Sulfate: SO4 2-

Question 17

Importance of ozone layer

Answer 17

Shields us from ultraviolet radiation form the sun

Question 18

How is the ozone layer being depleted?

Answer 18

Chlorofluorocarbons (CFCs). When CFCs are exposed to UV radiation, chlorine radicals are produced. These radicals destroy the ozone layer by reacting with ozone molecules forming chlorine oxide and oxygen

Question 19

Examples of greenhouse gases (trapping effect of heat energy)

Answer 19

Carbon dioxide
Methane
Water vapor