Small-Scale Acid Rain Lab
Environmental Chemistry
SCIENTIFIC
Introduction
All rainfall is acidic. However, when the acidity of rain falls below a pH of 5.6, it is referred to as acid rain. The most
common components of acid rain include various nitrogen and sulfur oxides produced from the combustion of fossil fuels
such as petroleum and coal. This activity simulates in a short time the possible effects on a variety of materials because of
acid rain.
Concepts
•pH
•Gas solubility
•Acid rain
Materials
Bromthymol blue solution, 0.04%
Apple skin, red
Calcium carbonate, CaCO3, 1 g
Green plant leaf
Magnesium ribbon, polished, 1 cm
Petri dish
Sodium sulfite, Na2SO3, 0.1 M, 1 mL
Universal indicator solution
Sulfuric acid, H2SO4, 3 M, 1 mL
Weighing dish
Water, distilled or deionized
Safety Precautions
Sulfuric acid is severely corrosive to eyes, skin and other tissues. Wear chemical splash goggles, chemical-resistant gloves and a chemicalresistant apron. Some students may be sensitive to the small amounts of sulfur oxides produced in this lab. A check for students with
asthma or allergies would be prudent. Wash hands thoroughly with soap and water before leaving the laboratory. Follow all laboratory
safety guidelines. Please review current Material Safety Data Sheets for additional safety, handling and disposal information.
Procedure
1. Carefully arrange the samples of apple flesh, apple skin, green leaf, magnesium, and CaCO3, a drop of bromthymol
blue, and a drop of universal indicator around the perimeter of the Petri dish.
2. Moisten the apple flesh, apple skin, green leaf and CaCO3, with a drop or two of distilled water.
3. Place the weighing dish in the center of the dish.
4. Add 10 drops of Na2SO3 and 5 drops of H2SO4 to the weighing boat. Caution: Do not slosh the solutions out of the
weighing dish onto the samples.
5. Place the top on the Petri dish.
6. Write down your initial observations on the colors and textures of the samples.
7. Set the Petri dish aside until the end of the class time. Record any changes you see before the end of class. Optional:
Leave the Petri dish and samples until the next class day to see if further changes occur.
Disposal
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures
governing the disposal of laboratory wastes. The contents of the weighing dish may be disposed of down the drain with
excess water according to Flinn Suggested Disposal Method #26b. The solids in the Petri dish may be disposed of
according to Flinn Suggested Disposal Method #26a.
© 2016 Flinn Scientific, Inc. All Rights Reserved.
Publication No. 91360
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Small-Scale Acid Rain Lab continued
Discussion
The lab produces more sulfur oxides than are typically found in acid rain. However, the lab samples were only in the acid
environment for a short time. In the real environment metals, plants, stones, and other items are exposed to the acidity for
many years.
The apple flesh probably remained fresh looking while in the acid environment, whereas an apple sample not in the Petri dish
turned brown. This is one reason that fruits and vegetables are often rinsed with lemon juice or citric acid solution, so they do
not turn brown (oxidize) in the air.
Changes in indicator solutions occur within a class period. Changes to the magnesium metal and the CaCO3 may require
overnight or longer in order to observe substantial changes.
Connecting to the National Standards
This laboratory activity relates to the following National Science Education Standards (1996):
Unifying Concepts and Processes: Grades K–12
Evidence, models, and explanation
Content Standards: Grades 5–8
Content Standard F: Science in Personal and Social Perspectives, natural hazards, risks and benefits, science and
technology in society
Content Standards: Grades 9–12
Content Standard F: Science in Personal and Social Perspectives, environmental quality, natural and human-induced
hazards, science and technology in local, national, and global challenges
References
Steve Long would like to thank Pat Chriswell for sharing this version of the acid rain lab.
Flinn Scientific—Teaching Chemistry™ eLearning Video Series
A video of the Small-Scale Acid Rain Lab activity, presented by Steve Long, is available in Environmental Chemistry, part of the
Flinn Scientific—Teaching Chemistry eLearning Video Series.
Materials for Small-Scale Acid Rain Lab are available from Flinn Scientific, Inc.
Catalog No.
S0253
S0417
C0347
M0139
Description
Sodium Sulfite Solution, 500 mL
Sulfuric Acid Solution, 3 M, 500 mL
Calcium Carbonate, 100 g
Magnesium, Ribbon
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
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© 2016 Flinn Scientific, Inc. All Rights Reserved.