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Natural Resources, Pollution, and Human Impact
29
Acid Rain
Seven friends were talking about acid rain. They each had different ideas about
acid rain. This is what they said:
Lynda:
I’ve heard that we have acid rain because of the hole in the ozone layer.
Sam:
All rain is acidic. This is normal.
Hank:
The rain didn’t used to be acidic. Global warming has made it acidic.
Otto:
Pollutants evaporate from lakes, rivers, and ground spills and come
down again as acid rain.
Elisa :
Acid rain is caused when normal rain combines with things in the air
that come from pollution.
Imani:
Acid rain used to be a big problem. Due to regulations and laws, there
is no more acid rain.
Paolo:
Carbon monoxide from automobile exhaust combines with rain to make
acid rain.
Which student do you agree with the most? ______________ Explain your thinking.
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Uncovering Student Ideas in Ear th and Environmental Science
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Natural Resources, Pollution, and Human Impact
Acid Rain
Teacher Notes
Purpose
The purpose of this assessment probe is to
elicit students’ ideas about pollution. The
probe is designed to uncover commonly held
ideas about acid rain.
Type of Probe
Friendly talk
Related Concepts
Acid rain, pollution
Explanation
The best answer is Elisa’s: “Acid rain is caused
when normal rain combines with things in
the air that come from pollution.” Oxides of
sulfur and nitrogen are produced from industrial pollution, such as the burning of coal.
These substances rise into the atmosphere,
where they mix and react with water to form
a more acidic pollutant, known as acid rain.
Normal rain is slightly acidic, with a
pH of about 5.7. The rain that falls on land
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contains some dissolved carbon dioxide from
the surrounding air. This causes rainwater to
be slightly acidic because of the carbonic acid
that is formed when pure water (pH 7) mixes
with carbon dioxide. This process is beneficial
in breaking down minerals found in the soil
to make them accessible to plants for nutrient
absorption. Acid rain resulting from reaction
with pollutants has a pH of about 4. The lower
the pH number, the more acidic the rain is.
Acid rain used to be a bigger problem than
it is today. The worst effects in the United
States were seen in the eastern states, which
have more concentrated industrialization. In
those areas, acid rain killed trees and harmed
lakes and streams. Some lakes were declared
biologically dead. The pH of rain in the northeast
in the 1950s and 1960s was commonly as low
as 4.0–4.5, with some storms delivering rain
with a pH as low as 3.0. Compare that with
the pH of vinegar, which is 2.4. Pollutants
from the factory smokestacks in the Midwest
are carried by the wind to the Northeast and
N a t i o n a l S c i e n c e Te a c h e r s A s s o c i a t i o n
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Natural Resources, Pollution, and Human Impact
exacerbate the problem. In Europe, acid rain
had a devastating effect on marble statues
and buildings.
In the United States, the Clean Air Act
of 1970 and the Acid Rain Program, established under Title IV of the 1990 Clean Air
Act Amendments, aggressively worked to
reduce emissions from power plants. The
efforts resulted in the highly acidic rains in
urban areas dropping to an average of pH
4.8 today. Unfortunately, we still experience
harmful acidic rains and need more work to
bring those pH levels down to a range that
does not damage natural systems or the built
environment, including marble statues and
stone that reacts with acid.
Administering the Probe
This probe is best used with students in grades
6–12 who have some knowledge of the basic
chemistry involved.
Related Core Ideas in
Benchmarks for Science
Literacy (AAAS 2009)
6–8 The Earth
The benefits of Earth’s resources—such
as fresh water, air, soil, and trees—can be
reduced by deliberately or inadvertently
polluting them. The atmosphere, the oceans,
and the land have a limited capacity to
absorb and recycle waste materials. In
addition, some materials take a long time
to degrade. Therefore, cleaning up polluted
air, water, or soil can be difficult and costly.
9–12 The Earth
Although the Earth has a great capacity
to absorb and recycle materials naturally,
ecosystems have only a finite capacity to
withstand change without experiencing
major ecological alterations that may also
have adverse effects on human activities.
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Related Core Ideas in A
Framework for K–12 Science
Education (NRC 2012)
6 –8 ESS3.C: Human Impacts on Earth
Systems
Human activities have significantly altered
the biosphere, sometimes damaging or
destroying natural habitats and causing the
extinction of other species. But changes to
Earth’s environments can have different
impacts (negative and positive) for different
living things.
9–12 ESS3.C: Human Impacts on Earth
Systems
Scientists and engineers can make major
contributions by developing technologies
that produce less pollution and waste and
that preclude ecosystem degradation.
Related Research
Khalid (2001) found that elementary
preservice teachers thought that pollutants
evaporate and come down as acid rain. He
also found a common misconception that
the students thought acids have a higher
pH than bases.
Darcin (2010) found that 76% of the
students sampled erroneously held the
idea that carbon monoxide is responsible
for acid rain. More than half (55%) saw
carbon dioxide as a factor of more acid rain.
Nearly half of the students (48%) thought
that chlorofluorocarbons cause acid rain.
Researchers have found that students of all
ages are aware of environmentally “friendly”
and “unfriendly” actions, and they know
about a range of environmental problems.
However, they tend not to link causes with
their consequences and may have a tendency
to imagine that all environmentally friendly
actions help to solve all environmental
problems (Driver et al. 1994).
Uncovering Student Ideas in Ear th and Environmental Science
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Natural Resources, Pollution, and Human Impact
Suggestions for Instruction and
Assessment
High school students can investigate the
effects of a solution of simulated acid
rain (4 ml of 1 M sulfuric acid in 2 L of
distilled water) on various materials that
might come in contact with acidic rain,
such as brick, marble, concrete, assorted
plant leaves, wood, different types of soils,
metals, and plastics. Students can brainstorm what materials to test and bring in
their own samples. The results can lead to
a discussion about the possible effects of
acid rain on the natural and built environment. (Safety notes: Have students wear
sanitized goggles, nitrile gloves, and aprons
throughout the activity. Have eyewash and
shower stations within 10 seconds access in
case of a splash. Review and share safety
instructions for handling sulfuric acid. Be
sure students wash their hands with soap
and water after completing the activity.)
Students can research the efforts being
made to reduce the harmful effects of acid
rain. A starting place for teachers is the
following Environmental Protection Agency
website: www.epa.gov/acidrain/reducing.
Students can create their own experiments to test the effects of acid rain on
plant germination. Obtain a variety of
fast-germinating seeds to sprout in various environments: pure water, normal
rain (captured on a rainy day), simulated
solution of acid rain (4 ml of 1 M sulfuric
acid in 2 L of distilled water), and diluted
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vinegar. (Safety notes: Have students wear
sanitized goggles, nitrile gloves, and aprons
throughout the activity. Have eyewash and
shower stations within 10 seconds access in
case of a splash. Review and share safety
instructions for handling sulfuric acid. Be
sure students wash their hands with soap
and water after completing the activity.)
Make connections to wind patterns to show
how factory and coal plant emissions from
one region in the United States (e.g., the
Midwest) can affect the air and water in
another region (e.g., New England).
References
American Association for the Advancement of
Science (AAAS). 2009. Benchmarks for science literacy online. www.project2061.org/
publications/bsl/online.
Darcin, S. 2010. Trainee science teachers’ ideas
about environmental problems caused by vehicle
emissions. Asia-Pacific Forum on Science Learning
and Teaching 11 (2): Article 14.
Driver, R., A. Squires, P. Rushworth, and V.
Wood-Robinson. 1994. Making sense of secondary
science: Research into children’s ideas. London:
RoutledgeFalmer.
Khalid, T. 2001. Preservice teachers’ misconceptions regarding three environmental issues.
Canadian Journal of Environmental Education
6 (1): 101–120.
National Research Council (NRC). 2012. A
framework for K–12 science education: Practices,
crosscutting concepts, and core ideas. Washington,
DC: National Academies Press.
N a t i o n a l S c i e n c e Te a c h e r s A s s o c i a t i o n
Copyright © 2016 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.
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