What Did You Discover?
1. Use the scroll bar to go to What is pH? Use the information you find to complete a chart
similar to the one that follows. For each substance in the list, give the pH and identify it as an
acid or a base.
pH
Substance
battery acid
lye
lemon juice
ammonia
vinegar
baking soda
sea water
milk
pH
1
13
2
12
3
8.5
8.5
6.5
Acid or Base (alkaline)
Acid
Base
Acid
Base
Acid
Base
Base
Acid
2. Draw and label a pH scale. Use the following labels: increasing acidity; neutral; increasing
alkalinity.
3. Complete the following statements.
What causes acid rain?
(a) Acid rain is rain , snow , or fog that is polluted by acid in the atmosphere and damages the
environment .
(b) The two common air pollutants are nitrogen oxide (NO2(g)) and sulphur dioxide (SO2(g)).
(c) These substances can travel far by prevailing winds and fall to Earth as acidic rain , snow ,
fog , or dust .
(d) Damage occurs when the environment cannot neutralize the acid.
What does acid mean?
(e) Acids have a sour taste and react with a base to form salts.
(f) Strong acids can burn your skin .
What is pH?
(g) The amount of acid in a liquid is measured using a pH scale.
Part B: Effects of Acid Rain
1. On Environment Canada’s Clean Air — Acid Rain web site, use the information on the web
page to complete the statements that follow.
What Did You Discover?
What is acid rain?
1. Normally, rain is slightly acidic (around pH 5) because it contains acids formed from the
reaction of gases with moisture in the atmosphere.
2. If the pH of rain falls below 5, it is called acid rain .
3. Burning fossil fuels produces nitrogen oxides and sulfur dioxides.
4. Most sulfur dioxide emissions come from smelters and power stations.
5. Most nitrogen oxide emissions come from motor vehicles .
6. Both of these pollutants can travel far in the atmosphere , where they mix with water vapour
to form a mild solution.
7. Rain and other precipitation wash the solution down to Earth as acid rain.
8. Acid rain affects most things it contacts, including soil , water , building materials and
plants .
9. In North America, most acid rain falls on the eastern part of the continent, because most of
the pollutants are produced there, and winds tend to blow toward the east.
Effects of acid rain
10. In the last 20 years, Canada has cut its sulfur dioxide emissions by more than half.
11. The recovery of natural ecosystems is much slower than expected and acid rain continues to
affect lakes , forests , wildlife , and our health .
Lakes
12. The more acidic a lake becomes, the fewer species can live there.
13. The first life forms to die from acidity are plankton and invertebrates .
14. More than 75 percent of the fish species disappear when the pH of a lake drops below 5.
15. The loss of fish species affects the food chain , including fish-eating birds, such as loons .
16. Some lakes resist becoming acidic because bases found in certain types of rock and soil
helps to neutralize the acids.
17. Most acid rain falls in eastern Canada, where the coarsely textured and granite bedrock are
not able to neutralize the acids.
18. Even after 2010 emissions targets are reached, up to one quarter of the lakes in eastern
Canada will be chemically damaged .
Forests
19. Acid rain dissolves nutrients and minerals in the soil and washes them away before trees
can use them.
20. Acid rain also releases chemicals, such as aluminum , which interfere with the uptake of
nutrients .
21. Nutrient-starved trees are less resistant to climatic stresses , pests , and disease .
22. Similar to a lake, a forest’s ability to resist acid rain depends on the capacity of its soils to
neutralize acids.
Human health
23. Carbon dioxide can react with other chemicals in the air to form tiny sulfate particles. These
particles can cause respiratory problems.
Corrosion
24. Acid rain speeds up the corrosion of materials such as limestone , sandstone , marble ,
brick , concrete , and metal.
25. Acid rain damages stonework because it dissolves calcium carbonate, leaving crystals .
26. As the crystals grow , they break apart the stone.
Acid rain and other pollutants
27. Interactions between acid rain, ultraviolet , UV radiation, climate change, and other stresses
can magnify their impacts.
28. For example, acidity reduces the amount of dissolved matter in lake water. As a result, acidic
lakes are clearer .
29. Clear lakes are more sensitive to increased UV levels.
30. Acid levels in lakes can be affected by climate changes.
31. For example, hot, dry conditions change harmless sulfur compounds into acid-forming
sulfates. When it rains, the sulfates end up in the surrounding lakes , which increases the acid
levels .
32. Click on ‘Air Quality’ – What are the many ways that Air Quality affect acid rain? Burning
fossil fuel also creates urban smog, climate change and releases mercury into the air.
33. Explain what happens to water quality due to acid rain? Acidity reduces the amount of
dissolved organic matter in the water, making it clearer and allowing the UV to penetrate to
greater depth.
3.
“Scrubbers” are antipollution systems that remove sulfur dioxide and contaminating
gasses resulting from the burning of fossil fuels. Traditional scrubbers remove sulfur dioxide gas
by reacting heated gases with calcium oxide or lime. The calcium oxide sorbent is used up in
this reaction and the waste calcium sulfite is disposed of, mostly in landfills. COBRA (copper
oxide bed regenerable application) uses a sorbent of small beads of aluminum oxide impregnated
with copper. The beads form cluster of copper oxide on their surface and as heated gases pass
by, sulfur dioxide gas reacts with the copper oxide to form copper sulfate. Fresh beads replace
spent beads. The spent beads are cleaned and reused.