Air and water Flashcards

1
Q

What are two chemical tests for water?

A

Cobalt (II) chloride: turns from blue to pink

Copper (II) sulfate: turns white to blue

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2
Q

What are two problems associated with lack of water?

A

Water used to irrigate crops - Crops cannot grow → lack of food for populations reliant on crops
No safe water for drinking: increased risk of disease

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3
Q

Describe the process of treatment of water supply (6)

A
  1. Water passed through metal screens and filtered for twigs/leaves
  2. In settlement tank, soil particles settle at bottom
  3. Aluminum sulfate added to make small particles in water stick together. Particles fall to bottom of tank
  4. Passed through filter made of sand and gravel, removes any insoluble particles not removed
  5. Chlorine added to kill bacteria
  6. pH of water adjusted, water run off
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4
Q

What are the uses of water in industry and in the home?

A

Generate electricity

Cooking, washing, cleaning

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5
Q

What is the composition of clean, dry air?

A

78% nitrogen, 21% oxygen and remainder: mixture of noble gases/carbon dioxide

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6
Q

Describe the separation of oxygen and nitrogen by fractional distillation (4)

A
  1. Water + carbon dioxide removed from air
    - Water by passing it through a drying agent
    - carbon dioxide by reacting it with sodium hydroxide
  2. Air is cooled to -23 degrees celcius and compressed
  3. Cold compressed air allowed to expand in larger space, air cools when expand until temp. drops to -200 degrees celcius - air is liquid
    - Argon, krypton and xenon are removed from oxygen by further distillation
  4. When liquid air is warmed, nitrogen boils off first (lower boiling point) + condenses
  5. Mixture fed to top column, oxygen condenses, nitrogen gas residue removed at top
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7
Q

What are the four common pollutants in the air?

A

carbon monoxide
sulfur dioxide
oxides of nitrogen
lead compounds

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8
Q

What are the sources + effects of carbon monoxide?

A

S:
incomplete combustion of carbon-containing substances
E:
reacts w/ haemoglobin, prevents from carrying oxygen, death

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9
Q

What are the sources + effects of sulfur dioxide?

A

S:
combustion of fossil fuels which contain sulfur compounds
E:
irritates eyes and throat, causes respiratory problems and acid rain

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10
Q

What are the sources + effects of oxides of nitrogen?

A
S:
car engines
denitrification
high temperature furnaces
E:
causes respiratory problems and acid rain
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11
Q

What are the sources + effects of lead compounds?

A

S:
burning of petrol
E:
causes damage to brain + nerve cells in young children

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12
Q

Describe the process of catalytic conversion of oxides of nitrogen in car engines (5)

A

Exhaust gases from car engine passed through a honeycomb (surface covered with metal catalysts) in a catalytic converter
Two compartments:
Compartment 1: metals catalyse conversion of nitrogen oxides to nitrogen
2NO(g) → N2(g) + O2(g)
2NO2(g) → N2(g) + 2O2(g)
Compartment 2: Carbon monoxide converted to carbon dioxide
2CO(g) + O2(g) → 2CO2(g)
Carbon monoxide may also react directly with nitrogen oxides (nitric acid + nitrogen dioxide)

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13
Q

What is needed for iron to rust?

A

Water and Oxygen

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14
Q

What are the four methods of rust prevention?

A

Paint
Plastic Coating
Galvanising
Sacrificial Protection

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15
Q

What is galvanising?

A

coating iron with zinc

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16
Q

What is sacrificial protection?

A

blocks of more reactive metal attached to iron surface

17
Q

What are NPK fertilizers used for?

A

replace essential elements lost when plants are harvested

18
Q

What causes the displacement of ammonia from its salts in soil?

A

Too much lime put in soil, displaces ammonia from ammonium salts, lost as gas

19
Q

What is ammonia’s function in soil

A

To neutralise soil acidity

20
Q

What is the Haber process?

A

Industrial manufacture of ammonia NH3

21
Q

What is the equation for the Haber process?

A

N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

22
Q

What are the raw materials required for the Haber process?

A

Nitrogen: from the air

Hydrogen

23
Q

What are the essential conditions required for the Haber process?

A

Temperature: 450°C
Pressure: 200 atm
Catalyst: Iron

24
Q

How does methane cause global warming?

A

Absorb heat energy and prevent it escaping into space - global warming

25
Q

How does carbon dioxide cause global warming?

A

heat is absorbed by carbon dioxide and becomes trapped within the Earth’s atmosphere → Earth becomes hotter

26
Q

What are the three ways carbon dioxide is formed?

A

Product of complete combustion of carbon containing substances
Product of respiration
Production of reaction between an acid and a carbonate

27
Q

What is the function of the carbon cycle?

A

keeps concentration of carbon dioxide in atmosphere constant

28
Q

What are the three main processes in the carbon cycle?

A

combustion, respiration, photosynthesis

29
Q

What is the equation for testing of water? (copper sulfate)

A

CuSO4(s) + 5H2O => CuSO4.5H2O(s)

30
Q

What is the equation for testing of water? (cobalt (II) chloride)

A

CoCl2 (s) + 6H2O (l) => CoCl2.6H2O

31
Q

Is treated water pure?

A

No

32
Q

What are the two oxides of nitrogen formed in internal combustion engines?

A

Nitric oxide: N2 + O2 → 2NO(g)

Nitrogen oxide: N2 + 2O2 → 2NO2(g)

33
Q

Why do oxides of nitrogen form in internal combustion engines?

A

Due to the high temperature and pressure inside an internal combustion engine which causes nitrogen and oxygen to combine