16 Pollution I - effects

Question 1

4 Most common effects of combustion emissions

Answer 1

• Smog and tropospheric (low-level) ozone
• Acid rain
• Ozone depletion
• Greenhouse effect

Question 2

Carbon combustion reaction equations

Answer 2

C + O2 -> CO2 + heat
or
2C + O2 -> 2CO + heat

Question 3

Hydrogen combustion equation

Answer 3

2H2O + O2 -> 2H2O + heat

Question 4

Sulphur combustion equation

Answer 4

S + O2 -> SO2 + heat (sometimes SO3 formed)

Question 5

What are intermediates?

Answer 5

Incompletely formed products of combustion. (unavoidable)

Question 6

Examples of intermediates

Answer 6

Soot (very fine carbon particles)
Complex hydrocarbons (heavy tars)

Question 7

Ways in which intermediates could arise

Answer 7

• Dissociation
• Incomplete Combustion
• Too rapid system
• Too hot system
• Too cold system

Question 8

What is smog?

Answer 8

Smoke and fog that gathers in urban zones

Question 9

What is smog caused by?

Answer 9

• Large amounts of coal burning
• Mixtures of particulate matter and sulphur dioxide

Question 10

What is Photochemical Smog?

Answer 10

When sunlight, NOx and VOCs chemically react in the atmosphere; leaving airborne particles and ground-level ozone. (New - discovered in 50s)

Question 11

What is ground level ozone?

Question 12

What highly reactive and oxidising chemicals does Photochemical smog include?

Answer 12

• Nitrogen Oxides
• Tropospheric Ozone
• Volatile organic compounds (VOCs)
• Peroxyacyl Nitrates (PAN)
• Aldehydes (R’O)

Question 13

What is Tropospheric Ozone?

Question 14

What are Volatile organic compounds?

Question 15

Who is most affected by ground level ozone?

Answer 15

Seniors
Children
People with heart/lung conditions

Question 16

How can the health effects of ground level ozone become worse?

Answer 16

• In areas surrounded by higher ground
• Conditions that encourage temp inversion

Question 17

3 Ways to reduce smog

Answer 17

• Low NOx technologies
• Particulate clean up
• Ozone reduction by oxidation/removal of NOx (reducing ozone precursors)

Question 18

‘Precursor’ definition

Question 19

What is Acid Rain?

Answer 19

Precipitation with a low pH that damages the ecosystem

Question 20

When does Acid Rain occur?

Answer 20

When sulphur dioxide and nitrogen oxides are emitted into the atmosphere and they undergo chemical transformations before being absorbed by water droplets in clouds.

Question 21

What is Acid Rain caused by?

Answer 21

• Natural sources (eg Volcanoes)
• Man made (most damaging)
  ( - sulphur dioxide is one of the biggest causes)

Question 22

Effects of smokestacks (chimneys)

Answer 22

Contributed to the spread of Acid Rain by releasing gases into regional atmospheric circulation. The acid rain deposition then occurs far downwind of the emissions, meaning only local pollution is helped.

Question 23

Where tends to get the most rainfall/acid rain?

Answer 23

Mountainous regions so they tend to receive the most acid rain. Eg Low pH of rain in Scandinavia compared to their local emissions.

Question 24

Effects of Acid Rain

Answer 24

• Depletes minerals from the soil which stunts the growth of plants. Plant life is killed due to loss of leaves/etc. (Extra fertilisers can help crops)
• Can affects some buildings, depending on their construction
• Water-based ecosystems receive the most damage as aquatic life is very sensitive to changes in pH
• (no immediate direct effects to human health)

Question 25

Typical sources of sulphur dioxide

Answer 25

(From largest to smallest):
Power stations
Other industries
Domestic
Commercial/public service
Refineries
Road transport

Question 26

What is the ozone layer?

Answer 26

Part of the earth’s atmosphere that contains relatively high concentrations (few ppm) of ozone O3.

Question 27

How does O3 (Ozone) help human life?

Answer 27

Absorbs biologically harmful UV radiation emitted from the sun

Question 28

Causes of ozone depletion

Answer 28

• free radical catalysts (eg NO, N2O, OH, Cl, Br)
• Chlorofluorocarbons (CFCs) (main cause)

Question 29

What are CFCs?

Answer 29

–

(regulated but still a problem

Question 30

Ozone depletion reactions with Chlorine.

Answer 30

Cl + O3 -> ClO + O2
ClO + O -> Cl + O2

Question 31

Effects of ozone damage

Answer 31

• increased risk of skin cancer
• reduction in crop yields due to enhanced UV radiation
• reduction in aquatic life due to loose of phytoplankton which affects the food chain
• climate change due to tropospheric chemistry changes (not proven)

Question 32

How significant is CO2 to climate change?

Answer 32

CO2 is one of the less potent gasses effecting climate change but is emitted in the largest amounts

Question 33

3 ways to reduce potential CO2 emissions from combustion:

Answer 33

• use a fuel that contains carbon produced from a non-fossil biomass source
• increase system’s efficiency
• capture and store the carbon emissions

Question 34

What is the role of CO2 and CH4 regarding human life?

Answer 34

CO2 and CH4 natural warm the planet’s surface and without them the earth would be ~30º lower; meaning earth would be inhabitable.

Question 35

How do greenhouse gases raise temp of earth?

Answer 35

They absorb long infrared radiation emitted as black body radiation from the earth. This slows radiation cooling and raises the equilibrium of the Earth.