Grade Level: Duration: Location: Vocabulary: 9th -12th grades
Two 60 minute class periods
Laboratory with fume hood
Acid rain
Damage Above and Below the Surface
Introduction:
The most common cause of the slight acidic nature of rain is naturally occurring carbon dioxide (either in the
atmosphere or the soil) that mixes with water to form carbonic acid. The equation for the formation of acid rain is:
H2O(l) + CO2(g) → H2CO3(aq)
When mixed with the calcium carbonate in limestone, the reaction is:
CaCO3(s) + H2CO3(aq) → 2CO2(g) + CaO(aq) + H2O(l)
Other forms of air pollution such as nitrous oxides and sulfur dioxide that result from burning fossil fuels form much
stronger acids when combined with water. These forms are what is usually referred to as acid rain and can cause
severe damage to rock structures and plant and animal life.
Engage:
Have students complete the “Disappearing Rock” activity for grades 6-8. After completing the rock cycle activity,
have students brainstorm the effects of acid rain on the rock cycle.
Materials for demonstration:
• Limestone rock
• Distilled water
•Vinegar
• Science notebook
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Sulfuric Acid (.1M solution)
Nitric Acid (.1M solution)
Bromothymol Blue pH indicator solution
4 Clear bowls (or cups) deep enough to cover the rock with solution
Explore:
1. Conduct the demonstration under a fume hood.
2. Label the bowls A, B, C, and D.
3. Pour 50 ml of water into bowl A, 50 ml of vinegar into bowl B, 50 ml of .1M nitric acid into bowl C, and 50 ml of
.1M sulfuric acid into bowl D.
4. Add 10 drops of Bromothymol Blue pH indicator. The solution will be slightly yellow in an acidic solution. As the
solution becomes more basic, it will turn green (neutral solution) and then blue (basic solution).
5. Have the students predict what reaction will occur between the rocks and the acids.
6. Submerge a small piece of limestone in each of the bowls. If you want to speed up the reaction, add powered
chalk to the solutions.
7. While waiting for the reactions to occur, show students pictures of the effects of acid rain on various objects.
Explain:
1. What are the equations for the three chemical reactions that occurred?
2. Why is acid rain so destructive?
3. How does acid rain affect the rock cycle?
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Elaborate:
1. Have students review the booklet “Living with Karst: A Fragile Foundation”. Do they live in a karst region?
2. If so, what is the major karst feature?
3. If the students do not live in a karst area, what is the closest location that has karst features? Describe those features.
Extension:
1. Have students collect a water sample during the next rain and compare/contrast the pH of rainwater to that of a
local stream.
2. What would cause the difference in pH?
Evaluate:
Have students research local sources of air pollution and types of air pollution produced. Based on their findings,
have students prepare a PowerPoint presentation on local air pollution and the effects on the environment.
KENTUCKY CORE ACADEMIC STANDARDS ALIGNMENT
Science
• HS-ESS2-5.C: The roles of water in Earth’s surface processes
• WHST.9-12.7: Conduct short as well as more sustained research projects to answer or solve a problem.
Social Studies
• 2.19 Students recognize and understand the relationship between people and geography and apply their
knowledge in real-life situations.
Suggested Reading/Resources
1. Acid Rain: Effects Felt Through the Food Chain http://environment.nationalgeographic.com/environment/globalwarming/acid-rain-overview/
2. Effects of Acid Rain: http://www.epa.gov/acidrain/effects/
3. Acid Rain: http://www.ncsu.edu/project/bio183de/Black/chemreview/chemreview_reading/acid_rain.html
4. Kentucky Ranks First in Toxic Air Pollution from Power Plants http://wfpl.org/post/kentucky-ranks-first-toxic-airpollution-power-plants
5. Earthsteps: A Rock’s Journey Through Time by Diane Nelson Spickert
6. Cracking Up: A Story About Erosion by Jacqui Bailey
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