http://quizlet.com/2640747/ib-chemistry-acid-deposition-sl-hl-flash-cards/
 http://www.chemistry.wustl.edu/~edudev/LabTutorials/Water/F
reshWater/acidrain.html
 http://www.chemistry.wustl.edu/~edud
ev/LabTutorials/Water/FreshWater/acidr
ain.html
What is Rain
 Rain is usually acidic, ph 5.65 , because it
 dissolves and
 reacts with carbon dioxide as it falls through
the air.
 Carbon dioxide forms a weak acid in water:
CO2(g) + H2O(l) => H2CO3(aq)
 Acid deposition refers to the process by
which acidic particles, gases and
 precipitation leave
 the atmosphere,
 There are two types of acid deposition:
 Wet and Dry.
Acid Rain
 Acid Rain is a type of wet deposition,
precipitation(rain, snow, hail)
that has a pH lower than 5.6
 It is formed when(sulfur& nitrogen oxides)
1. sulfur dioxide (combustion of fossiul fuels or
smelting of sulfide ores)
2. nitrogen monoxide(internal combustion engines)
and nitrogen dioxide
gases in the atmosphere, combine with water
vapor and precipitate as sulfuric acid or nitric.
Formation of Sulfuric Acid (H2SO4)
S(s) + O2(g) => SO2(g)
2SO2(g) + O2(g)(air) 2SO3(g)
SO3(g) + H2O(l)(rain)H2SO4(aq)
Formation of Nitric Acid (HNO3)
N2(g) + O2(g) => 2NO(g) (engines,high T)
2NO(g) + O2(g) (air)2NO2(g)
2NO2(g) + H2O(l)(rain) HNO3(aq)+HNO2 (aq)
directly producing nitric acid in water.
Sources OF
ACID RAIN
SO2
NOX
Sources
of Acid Rain //www.youtube.com/watch?v=RP-sU8i2edo&feature=fvst
 The principal cause of acid rain is from human
sources




Cars,vehicles,nitrogen monoxide
Industrial factories, power-generating plants and
vehicles
Sulfur dioxide and oxides of nitrogen are released
during the fuel burning process (i.e. combustion)
Sulfur dioxide
accounts for about
90 % of all acid
rainfall
MSN Encarta
Formation of Acid Rain
Acidic Rain Deposition
• Acidic particles and vapors are deposited via two
processes - wet and dry deposition.
• Wet deposition is acid rain, the process by which acids
with a pH normally below 5.6 are removed from the
atmosphere in rain, snow, sleet or hail.
• Dry deposition takes place when particles such as fly ash,
sulfates, nitrates, and gases (such as SO2 and NO), are
deposited on, or absorbed onto, surfaces.
http://myecoproject.org/get-involved/pollution/acid-rain/
 Acid rain often precipitates miles away
from its source.
 Causes damages to building materials
(carbonates).
 Affects vegetation by leaching minerals
from soil.
 Affects aquatic life by altering pH of
 rivers.( below 4, dead)
 Affects human health by increasing
respiratory diseases.
 Buildings made of stone become
 corroded, as the sulfuric acid in acid
 rain reacts with the calcium carbonate
 to form _____, which can be washed
 away
Harmful Effects of Acid Rain
 Harmful to aquatic life


Increased acidity in water bodies
Stops eggs of certain organisms (e.g. fish)
to stop hatching
 Changes population ratios
 Affects the ecosystem
Effects of Vegetation
 Harmful to vegetation




Increased acidity in soil
Leaches nutrients from soil, slowing plant growth
Leaches toxins from soil, poisoning plants
Creates brown spots in leaves of trees, impeding
photosynthesis
 Allows organisms to infect through broken
leaves
Effects of Acid Rain
on Vegetation
http://abacus.bates.edu/~ganderso/biology/bio270/clover_leaf_bu
rns_pH2_30d.gif
MSN Encarta
Effects of Acid Rain on
Buildings and Structures
 Marble is particularly susceptible
 Accelerates weathering in metal and
stone structures
 Eg. Parthenon in Athens, Greece;
Taj Mahal in Agra, India
MSN Encarta
http://www.lauraknauth.com/photos/france/thinker.jpg
Effects of Acid Rain on
Human Health
 Affects human health



Respiratory problems, asthma, dry coughs,
headaches and throat irritations
Leaching of toxins from the soil by acid rain can
be absorbed by plants and animals. When
consumed, these toxins affect humans severely.
Brain damage, kidney problems, and Alzheimer's
disease has been linked to people eating "toxic"
animals/plants.
Preventive Measures
 Reduce amount of sulfur dioxide and
oxides of nitrogen released into the
atmosphere



Use less energy (hence less fuel burned)
Use cleaner fuels
Remove oxides of sulfur and oxides of
nitrogen before releasing
 Flue gas desulphurization
 Catalytic Converters
Preventive Measures
 Use cleaner fuels



Coal that contains less sulfur
"Washing" the coal to reduce sulfur
content
Natural Gas
Preventive Measures
 Flue Gas Desulfurization (FGD)



Removes sulfur dioxide from flue gas (waste gases)
Consists of a wet scrubber and a reaction tower
equipped with a fan that extracts hot smoky stack
gases from a power plant into the tower
Lime or limestone (calcium carbonate) in slurry
form is injected into the tower to mix with the
stack gases and reacts with the sulphur dioxide
present
Preventive Measures
 (continued)


Produces pH-neutral
calcium sulfate that is
physically removed from
the scrubber
Sulfates can be used for
industrial purposes
Scrubber at work
MSN Encarta
Alkaline Scrubbers
Preventive Measures
 Use sources other than coal to generate
electricity
•
•
•
•
•
nuclear power
hydro-electricity
wind energy
geothermal energy,
solar energy
 Issue of cost
http://upload.wikimedia.org/wikipedia/commons/4/4e/Nuclear_Power_Plant_Cattenom.jpg
Reducing the effects of Acid
Rain
 Liming



Powdered limestone/limewater
added to water and soil to
neutralize acid
Used extensively in Norway and
Sweden
Expensive, short-term remedy