Air and Water

Question 1

Composition of air

Answer 1

78% nitrogen
21% oxygen
the remaining 1% is a mixture of noble gases and carbon dioxide

Question 2

How can nitrogen and oxygen be separated

Answer 2

By liquefying air first and then separating the two gases through fractional distillation.

Question 3

Air liquefication

Answer 3

Air is first filtered to remove dust
Cooled to -200 degrees to make gas air into liquid

Question 4

Fractional distillation of liquid air

Answer 4

Liquid air passed into bottom of fractionating column
Column warmer at the bottom than the top
Liquid nitrogen boils at the bottom of the column
Gaseous nitrogen rises to the top where it is piped off at stored
Liquid oxygen collects at the bottom of the column

Question 5

Carbon monoxide source

Answer 5

It is formed when carbon is heated in a limited supply of air
2C + O2 = 2CO

Question 6

Adverse effects of carbon

Answer 6

It binds permanently to red blood cells and prevents haemoglobin

Question 7

Sulphur dioxide source

Answer 7

Burning of fossil fuels containing sulphur
S + O2 = SO2

Question 8

Adverse effects of sulphur

Answer 8

Acid rain causing deforestation and building damage

Question 9

Oxides of nitrogen source

Answer 9

Nitrogen and oxygen reacting at high temperatures in car engines
N2 + O2 = 2NO
2NO + O2 = 2NO2

Question 10

Adverse effects of oxides of nitrogen

Answer 10

Causes severe respiratory problems and acid rain

Question 11

Lead compounds source

Answer 11

leaded petrol

Question 12

Adverse effects of lead compounds

Answer 12

damage to the brain and nervous system

Question 13

Rusting

Answer 13

Rusting is the red/orange coating that forms on the surface of iron when exposed to air and moisture.
Hydrated iron (III) oxide

Question 14

Rust prevention methods

Answer 14

Painting
Using oil grease
Galvanizing
Plating
Coating with plastic

Question 15

Three elements needed in healthy plant growth

Answer 15

Nitrogen, phosphorus and potassium

Question 16

How is ammonia manufactured

Answer 16

Ammonia is manufactured from nitrogen and hydrogen through the haber process

Question 17

How is ammonia manufactured

Answer 17

Ammonia is manufactured from nitrogen and hydrogen through the haber process

Question 18

How are nitrogen and hydrogen obtained

Answer 18

Nitrogen is obtained from the air. Hydrogen is made from methane (natural gas)

Question 19

Conditions for the haber process

Answer 19

450 degrees Celsius
200 atmospheres
Iron catalyst

Question 20

why is the temperature above 450 degrees not used

Answer 20

This is because the forward reaction is exothermic and higher temperatures will favor the reverse reaction and therefore reducing yield. Too low temperatures on the other hand, will also lower reaction rates too. 450 degrees celsius is a good mid point.

Question 21

Methods of forming carbon dioxide

Answer 21

By complete combustion of carbon-based fuel
By reaction of carbonates with acids to form a salt, carbon dioxide and water
Thermal decomposition of a carbonate

Question 22

Main source of methane

Answer 22

Decomposition of vegetation and waste gases from digestion in animals

Question 23

Water will turn anhydrous copper (II) Sulfate from

Answer 23

white to blue

Question 24

Water will turn anhydrous cobalt chloride from

Answer 24

blue to pink

Question 25

Treatment of water

Answer 25

Filtration (through sand and gravel filters) to remove undissolved solids
Treated with chlorine to kill bacteria

Question 26

Effects of inadequate water supply

Answer 26

Reduced crop yield
Negative health impact (diarrhea)