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SCH4U > U2 - Earth & Space Science > Flashcards

U2 - Earth & Space Science Flashcards

1
Q

What are the natural and anthropogenic (artificial, by humans) causes of H2O, CO2, CH4, N2O, O3 and CFC’s?

A 
(H2O) Natural = evaporation
Anthro. = burning fossil fuels
(CO2) Natural = respiration
Anthro. = burning fossil fuels
(CH4) Natural = decay of organic matter
Anthro. = decay of landfills
(N2O) Natural = decomposition in soil
Anthro. = fertilizers
(O3) Natural = occurs naturally in stratosphere
(CFC's) Anthro. = refrigerants, air conditioning units
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2
Q

What is the Greenhouse Factor?

A

The ability of a greenhouse gas to absorb infrared radiation (IR) from the sun relative to CO2.

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3
Q

What three factors does the surface temperature of the Earth depend on?

A
  • Absorption and reflection of UV rays
  • Amount of sunlight received
  • Extent to which atmosphere retains heat
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4
Q

What is the Natural Greenhouse Effect?

A

The absorption and reflection of UV rays by naturally occurring CO2 and H2O in the atmosphere which keeps the Earth at an inhabitable temperature.

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5
Q

What pattern is observed between global temperatures and the concentration of greenhouse gases?

A

As temperatures increase, so do the concentration of GH gases.

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6
Q

What is the correlation between industrial human activities and the Earth’s surface temperature?

A

The amount of greenhouse gases caused by human industrialization coincides with an increase in surface temperatures.

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7
Q

Explain the Enhanced Greenhouse Gas Effect and the outcome.

A

Explanation: Incoming solar radiation is high energy and shorter wavelength. The Earth absorbs some of this energy (so incoming E is higher than reflected E, which is now lower and of longer wavelength). Greenhouse gases in the atmosphere trap this energy and increase the Earth’s temperature (ex. CO2 is a one way filter for sunlight!).

Outcome: Increase in global temperatures from 2 - 6 degrees Celsius.

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8
Q

Define the term Climate Change.

A

Long-term effects on temperature that can lead to permanent implications (usually an increase in temperature).

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9
Q

Name 5 consequences of climate change.

A
  • Global temperatures have increased 0.5 degrees Celsius.
  • Precipitation has increased by 1%.
  • Sea levels have increased 15 - 20cm due to the melting of glaciers, polar ice caps, and the physical expansion of oceans
  • Pathogens and insects altered by climate (ex. spread of malaria)
  • Crop yields and geographic distribution is affected
  • Forests: insects + diseases may increase
  • Water resources: increased rainfall leads to flooding, and decrease in precipitation due to warm temperatures in some areas lead to drout
  • Beach erosion (elevated water levels)
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10
Q

What is a Carbon Footprint?

A

A measure of the amount of greenhouse gases and CO2 a person uses in their day-to-day activities.

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11
Q

Give an example of biological and geographical sequestration of CO2.

A

Biological - capture and storage of CO2 by growing plants.

Geographical - control of CO2 by storing it underground.

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12
Q

Define the term Global Dimming.

A

The reduction of surface temperatures by the production of pollutants like soot or volcanic ash. These particles reflect sunlight back into space.

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13
Q

Ozone and Oxygen are allotropes of each other. Define “allotropes” and show how they are different using structure, bond order, and dissociation wavelengths.

A

“Allotropes” - different structural formulas of the same element.

O2 = two O atoms double-bonded to each other; bond order 2; wavelength needed to break bond is 242nm (because double bond requires higher energy to break)

O3 = 3 O atoms, 2 double-bonded and another single-bonded to each other; bond order 1.5; wavelength needed to break these bonds is 330nm (because single + double bonds don’t require as much energy to break)

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14
Q

What are the dissociation reactions of O2 and O3?

A

Oxygen gas: O2 + uv > 2 O .
Ozone: O3 + uv > O . + O2
O3 + O . > 2 O2

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15
Q

Describe the structure of O3 (VESPR structure, net dipole, formal charges, e.t.c.)

A
  • “bent” derived from trigonal planar
  • Sp2 hybridized
  • overall FC = 0
  • resonance structure … delocalized electrons
  • net dipole pointing away from middle O
  • bond angle is 117 degrees due to unpaired electrons on middle O
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16
Q

What are the equations for the natural formation and depletion of ozone?

A

Formation:
O2 + uv > 2 O .
O2 + O . > O3

Depletion:
O3 + uv > O2 + O .
O3 + O . > 2 O2 (rate-determining step) r = k[O .][O3]

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17
Q

Describe the two types of acid deposition.

A

Wet: rain, snow, or sleet that contains dissolved acids.
Dry: dust or particles that, when in contact with water, dissolve to produce acids.

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18
Q

What are the causes of sulfur and nitrogen oxides in the atmosphere?

A

Sulfur: burning of fossil fuels, burning of coal, metal smelting (refining)

Nitrogen: fuel engines and furnaces

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19
Q

What are the reactions for the formation of sulfurous acid (H2SO3) and sulfuric acid (H2SO4)?

A

Sulfurous:
S + O2 > SO2
SO2 + H2O > H2SO3

Sulfuric:
SO2 + 1/2 O2 > SO3
SO3 + H2O > H2SO4

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20
Q

What are the reactions for the formation of NOx molecules and nitrogen-containing oxyacids?

A

NOx:
N2 + O2 > 2 NO
2 NO + O2 > 2 NO2
N2 + 2 O2 > 2 NO2

Nitrogen-containing oxyacids:
H2O + 2 NO2 > HNO2 + HNO3
2 H2O + 4 NO2 + O2 > 4HNO3

21
Q

State the evidence of catalytic destruction of ozone.

A
  • O3 in atmosphere has decreased since the 1970’s
  • Increased vehicle emissions (increase NOx)
  • Use of CFCs
22
Q

What are the reactions for the catalytic destruction of ozone by NOx and CFCs? (state the catalysts and the intermediates).

A 
NOx:
NO . + O 3 > NO2 + O2
NO2 + O . > NO . + O2
Catalyst: NO .
Intermediate: NO2
CFCs:
(CCl2F2 + uv > CClF2 . + Cl .)
Cl . + O3 > ClO + O2
ClO + O. > Cl . + O2
Catalyst: Cl .
Intermediate: ClO
23
Q

Explain the effects of acid deposition on limestone/marble (CaCO3) and metals. Use chemical equations to support your answer.

A

Materials: acids can cause limestone buildings and marble structures to erode into soluble nitrates and sulfates.

Metal: acid rain can accelerate oxidation of Fe.

24
Q

What are some ways we reduce SO2 and NOx emissions?

A 
SO2
Pre-combustion: 
-metal sulfites removed by rinsing
-oil reached w/ H2 to form H2S, which is then captured and converted to elemental S
Post-combustion:
(SO2 removed as solid CaSO4 dry wall)
CaO + SO2 > CaSO3
CaCO3 + SO2 > CaSO3 + CO2
2 CaSO3 + O2 > 2 CaSO4

NOx
-catalytic converters in vehicles (precious metals like Pd and Pt):
2 CO + 2 NO > 2 CO2 + N2
-use of low temperature burners (like industrial-size furnaces for heating).

25
Q

What is the relationship between DO and BOD?

A

Inverse relationship (increase in O2 = decrease in BOD and vice versa)

26
Q

What is DO?

A

Dissolved Oxygen in a body of water.

At normal water temperature 20°C, the [DO] is about 2.8 x 10^-4 mol/L.

27
Q

What is BOD?

A

A measure of the amount of oxygen needed to decompose all biodegradable waste and ammonia in a body of water.

28
Q

What is effluent?

A

Liquid waste that leaves an industrial plant.

29
Q

How is BOD measured?

A

An effluent sample is taken and left in O2 saturated water. The container is vacuum sealed and left for a period of five days. The decrease in DO is then measured using an O2 electrode. The greater the amount of O2 demanding waste in the effluent, the higher the BOD.

30
Q

Give examples of anaerobic decomposition.

A

CH4, ammonia and amines, H2S, phosphine (PH3)

31
Q

Describe the process and sources of eutrophication.

A

Sources:

  • nitrates from human and animal waste
  • phosphates from fertilizers and detergents

Process:

  1. Aerobic decomp. of dead plants reduces DO
  2. Fish die from asphyxiation
  3. Anaerobic decomp. of dead plants produces H2S and phosphines, making water unfit to support life.
32
Q

What happens when there are high levels of O2 demanding waste in a body of water?

A

There is not enough DO to compensate and anaerobic bacteria take over.

33
Q

A reaction is photochemical when it ___________ ?

A

Requires UV light.

34
Q

Explain the seasonal variation of the ozone levels and how it can account for the depletion in Antarctica.

A
  1. In polar winter (June-Sept), temperatures can reach -90°C and cause water vapour to form ice crystals in the air. Ice crystals = surface catalysts on which molecules from pollutants may react (ex. Cl2)
  2. In polar spring (October), UV from the sun converts the Cl2 into free radicals which catalyze the depletion of O3 (worst)
  3. Later into the spring (November-December), the ice crystals melt and Cl2 production drops off. The warmer surface temperatures replenish the O3.
35
Q

What is the pH of pure rain water? Explain using chemical equations. (Hint: CO2 makes WATER more acidic.)

A

pH = 5.6

CO2 + H2O > H2CO3

H2CO3 > H+ + HCO3-
(Weak acid)

36
Q

Show the impact of acid on limestone and marble structures using chemical equations.

A

Dry:
2 CaCO3 + 2 SO2 + O2 > 2 CaSO4 + 2 CO2

Wet:
CaCO3 + H2SO4 > CaSO4 + H2O + 2 CO2
CaCO3 + 2 HNO3 > Ca(NO3)2 + H2O + CO2

37
Q

Explain the effect of thermal pollution and how it affects DO.

A

Thermal pollution is caused by the dumping of heated water into lakes, rivers and oceans, reducing the solubility of gases.

This decreases DO and increases metabolic rates in aquatic organisms, thus increasing BOD.

38
Q

Explain the effect of acid deposition on plants.

A

Plants: acids can slow the growth of plants and cause lethal damage. They can also leach valuable minerals from the plants (K+, Ca) and expose them to toxins like Al. Dry deposition blocks the pores on plant leaves preventing gas exchange.

Water: makes marine ecosystems unable to support life. Al released into the water is poisonous and can interfere with a fish’s gills, preventing a sufficient oxygen supply. NO3- released from fertilizers can cause excess plant growth (eutrophication).

Human health: no direct effect, except acids may affect the respiratory track and irritate eyes. Acids may enter pipes and contaminate water supply with hard metals (ex. Pb).

39
Q

Explain the effects of acid deposition on water.

A

Makes marine ecosystems unable to support life. Al3+ released into the water is poisonous and can interfere with a fish’s gills, preventing sufficient oxygen supply. NO3- released from fertilizers can cause excess plant growth (eutrophication).

40
Q

Explain the effect of acid deposition on human health.

A

No direct effect, except acids may affect the respiratory track and irritate eyes. Acids may enter pipes and contaminate water supply with hard metals (ex. Pb).

41
Q

List three things found in water and their effects.

A
  1. Arsenic (in trace amounts) - converts minerals to groundwater. If more than 5ppb, linked to cancer and diabetes.
  2. Fluoride - stains teeth, but in trace amounts, offers extra protection to teeth.
  3. Calcium from limestone - reacts w/ soap to form insoluble ‘soap scum’
42
Q

Name four water contaminants.

A
  1. Lead (old pipes, smelting, car batteries - leads to kidney, nerve and brain damage)
  2. Mercury (coal plants, mines, cement plants, volcanoes - affects central nervous system, liver, kidneys)
  3. Nitrate and phosphate (livestock, fertilizers - leads to increase in crop yields but also runoff)
  4. Leachate (plastics - leads to breast cancer and heart disease)
43
Q

Name four water contaminants.

A
  1. Lead (old pipes, smelting, car batteries - leads to kidney, nerve and brain damage)
  2. Mercury (coal plants, mines, cement plants, volcanoes - affects central nervous system, liver, kidneys)
  3. Nitrate and phosphate (livestock, fertilizers - leads to increase in crop yields but also runoff)
  4. Leachate (plastics - leads to breast cancer and heart disease)
44
Q

What are the 12 principles of green chemistry?

A
  1. Waste prevention
  2. Atom economy
  3. Less hazardous chemical synthesis
  4. Designing safer chemicals
  5. Safer solvents & auxiliaries
  6. Design for energy efficiency
  7. Use of renewable feedstocks
  8. Reduce derivatives
  9. Catalysis
  10. Design for degradation
  11. Real-time pollution prevention
  12. Safer chemistry for accident prevention
45
Q

How does salt content and high temperatures affect DO?

A

Salt content: a lot of salt = a lot of space taken up, reduces DO

High temperatures: KE accelerates movement of the molecules and causes gas to escape, reduces DO

46
Q

What are the 1°, 2° and 3° steps to sewage treatment and what is removed in each?

A

1° Mechanical Separation
> Screens/settling tank
> Flocculation (Alum forms ppt’s with large particles)
> Removes shit, motorcycles, bodies

2° Microbial Activity
> Sewage is aerated w/ O2-rich water
> Sedimentation tanks
> Removes 90% O2-demanding organisms

3° Chemicals are added
> ppt’s form to filter out harmful substances
> Carbon beds absorb pathogens
> Removes nitrates, phosphates, heavy metal ions

47
Q

What are two desalination methods?

A

Distillation:
Industrial plants use distillation to separate water from the salt. Large use of oils from coal plants makes it unsustainable and counterintuitive.

Reverse osmosis:
Energy is also required to apply pressure to a body of water so it performs reverse osmosis, from more concentrated to less concentrated across a semi-permeable membrane.

48
Q

What are two methods to counter hard water?

A
  • Water softeners

- Washing sodas (ex. CLR)

SCH4U (8 decks)

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