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Environmental Chemistry Flashcards

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1
Q

Normal ph of rain water and how it is lowered

A

5.6

CO2 in atmosphere combines with H2O forming carbonic acid which dissociates weakly.

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2
Q

Gases causing acid rains

A

NO, NO2, SO2, SO3

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3
Q

Natural processes adding NO and NO2 to atmosphere

A

Lightning, volcanic eruptions, nitrifying bacteria, oxidation of ammonia

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4
Q

Artificial processes adding NO and NO2 to atmosphere

A

Burning fossil fuels

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5
Q

Natural processes adding SO2 and SO3 to atmosphere

A

Volcanic eruptions, Microbial activity taking place anaerobic conditions of the sediments of ocean beds and water bodies

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6
Q

Artificial processes adding SO2 and SO3 to atmosphere

A

Oxidation of S contained as impurities in diesel, oil used in crude oil refining and coal

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7
Q

Effects of the acidification of water

A

changes in behavioural patterns, retardation of organogeny and destruction of eggs and immature organisms of fish and other aquatic organisms

Death of coral polyps

Owing to the acidity, poisonous metal ions (Al3+, Cd2+, Cr2+, Hg2+) and other toxic ions strongly bound to the insoluble soil structure get detached and dissolve in water.

raises the hardness of water.

damage statues and other artistic creations made of calcium carbonate minerals such as marble

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8
Q

Measures that could be taken to reduce acid rains and acidification of water

A

(i) Burning coal with substances (CaCO3) that can react with sulphur dioxide (Fluidized bed combustion)
CaCO3(s)——-> CaO(s) + CO2(g)
CaO(s) + SO2(g)——> CaSO3(s)
(ii) Converting sulphur dioxide in power plant waste gases into solid substances. (reacting with calcium hydroxide (Lime slurry process))
Ca(OH)2(aq) + SO2(g)—–> CaSO3(s) + H2O (l)

Using coal and diesel with low sulphur content in coal and diesel power plants.

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9
Q

Greenhouse gases definition

A

gases which can absorb infrared radiations exist stably in the atmosphere for a long period of time are referred to as greenhouse gases.

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10
Q

Green house gases

A

H2O, CO2, CH4, N2O, CFC, HFC, HCFC

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11
Q

Processes adding methane

A

Disposal of urban wastes as heaps of garbage

Agricultural practices (paddy cultivation) undertaken in marshy and water-logged areas

Produced in the guts of the ruminants like cattle

Crude oil mining

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12
Q

Effects of global warming

A

Polar ice caps and glaciers in high mountains areas tend to melt while the oceanic waters expand.

Because of the high temperature epidemics (e.g; dengue, Ebola) spread fast.

Frequent emergence of hurricanes, tornadoes

Frequent long-standing droughts and flash floods

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13
Q

Measures to minimise global climatic changes

A

Limited the burning of fossil fuels, getting used to vegetarian diet, Minimizing deforestation, use renewable sources of energy such as ethanol and biodiesel

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14
Q

Mean wavelength of radio waves

A

1 cm

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15
Q

Mean wavelength of micro waves

A

1 mm

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16
Q

Mean wavelength of infrared waves

A

10 μm

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17
Q

Mean wavelength of visible waves

A

500 nm

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18
Q

Mean wavelength of UV waves

A

250 nm

19
Q

Mean wavelength of X waves

A

1 nm

20
Q

Divisions of the atmosphere and its major characteristics

A

Troposphere This stretches from the Earths surface to about 15 km upwards. A greater percent (about 99%) of the atmospheric gases is found in this region.Ascending from the Earth’s surface, the temperature decreases.

Stratosphere - The region from 15 km to 50 km from the Earth’s surface is stratosphere. The percentage of gases here is very low and ascending the layer, the temperature increases.

Thermosphere - It is the region above 50 km from the Earth’s surface. Amount of gases in this region is extremely small and the temperature is very high.

Ozone layer - A sub-zone in the stratosphere is referred to as the ozone layer. This extends from 20 km to about 35 km from the Earth’s surface. This is called ozone layer because most of the naturally occurring ozone gas in the Earth (around 95%) is found in this region.

21
Q

Causes for ozone layer depletion

A

Sulphur containg compounds added to the upper atmosphere during powerful volcanic eruptions

  1. Chlorofluorocarbon
    In addition to this, volatile organic compounds containing bromine (bromofluorocarbon)
  2. Nitric oxide (NO) gas emitted by the aircrafts flying close to the upper atmosphere also depletes the ozone layer.
22
Q

Industrial application of CFCs

A
  1. Used as the coolant gas in air conditioners and refrigerators
  2. Used as an aerosol spray under high pressure in perfumes
  3. Used as a blowing agent in the production of foam plastic
  4. Bromofluorocarbons are used in fire extinguishers.
23
Q

How CFCs contribute to ozone layer depletion

A

CFCs are stable and highly volatile. They get evaporated and reaches to the stratosphere where it is exposed to UV radiation forming Cl free radicals. These free radicals react with ozone

24
Q

Effects of ozone layer depletion

A

Skin cancer
Cataract in eyes
Mutations
Bleaching

25
Q

Alternatives used at present for CFCs

A

Isobutane
hydrofluoroolefin

26
Q

Requirements and chemical pollutants causing photochemical smog

A

NO, CH3(CH2)nCH3 (n = 1- 4)

sunlight and a temperature above 15 C

27
Q

Main product formed during photochemical smog

A

O3

28
Q

Adverse effects of the photochemical smog

A

Ozone is a toxic gas. When inhaled it causes respiratory complaints destruction of mucous membranes in the respiratory tract.

when plants are exposed to ozone yellow spots appear especially in tender leaves due to destruction of chlorophyll.

reducing the mechanical strength of rubber-based products.

Ozone bleaches colourings.

29
Q

Least polluted form of water in the water cycle

A

Atmospheric water

30
Q

pH of drinking water

A

6.5- 8.5

31
Q

Eutrophication

A

The excessive growth of algae due to addition of nutrients to the water is defined as eutrophication.

32
Q

Processes occurring during eutrophication

A

Due to the excessive growth of algae on the surface sunlight do not penetrate and reach the bottom surface which prevents photosynthesis from happening. Due to the production of H2S under anaerobic conditions area becomes foul smelling.

Major limiting factors for algal growth are phosphate ions and nitrate ions

33
Q

If algal growth has to be stopped, PO4 3- level should be maintained at

A

0.05 ppm

34
Q

Human activities causing eutrophication

A

agriculture
disposal of industrial waste
addition of domestic detergents

35
Q

Heavy metals definition

A

metal whose density is greater than 5 g cm-3 or a metal whose relative density stands above 5

atomic number greater than 20.

cations which give insoluble precipitates with sulphide ions (S2-) and hydroxide ions (OH-)

36
Q

Sources of heavy metals

A

Industrial emissions, mining waste, leaded gasoline, leaded paints, metal pipe welding materials

37
Q

Effects of dissolved hydrocarbons

A

When they occur in water, they are decomposed by bacteria. This increases the oxygen demand of water and decreases the dissolved oxygen level (DO).

38
Q

Disorders caused due to heavy metals

A

Brain damage, insomnia, kidney damage, minamata disease, Arsenicosis

39
Q

PbCrO4 colour

A

yellow

40
Q

Products of photochemical smog other than ozone

A

PAN (peroxyacetylnitrate)
PBN (peroxybencylnitrate)
voltile aldehydes
particle matter

41
Q

How to identify CFC, HFC and HCFC

A

CFC contains 1 C atom and all other atoms are Cl and F

HFC contains 1/2 C atoms,1 H atom and all others are F

HCFC contains 1 C atom, 1 H atom and all others are Cl and F

42
Q

Plastic cups are made up of

A

Polystyrene

43
Q

Uses of bakelite

A

Used to make heat stable components of electrical circuits

Chemistry (15 decks)

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