Hands-on Activity: Acid Attack
Educational Standards :
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
For each group:
For the teacher/instructor:
Introduction/Motivation (Return to Contents)
Acids can also be found in the air around us — specifically in polluted air. Acid rain happens when air pollution chemicals, which come from fuel-burning factories or cars, react to form acids in the air. The acids from burning fuel in the air attach to water molecules in the air and fall as rain or snow. We call the breakdown caused by acid rain, chemical erosion. The effects of acid rain (chemical erosion) include: damage to statues and buildings; weakening of the exposed metal on bridges and playground equipment; damage to wildlife, plants, forests and crops; and the contamination of drinking water supplies.
Procedure (Return to Contents)
Acid rain is formed by complex chemical reactions involving air pollution. The two main pollutants in acid rain are oxides of nitrogen and sulfur that react with rain moisture to form nitric and sulfuric acid. Mainly, these erosive pollutants come from manmade sources such as cars or fossil fuel-burning plants. Acid rain contaminates the environment not just through rain, but also through snow, fog, dew and dust.
Lemon juice and vinegar are the acids used in this activity to simulate acid rain. Chalk is made up of limestone, which will simulate a statue. Limestone contains calcium carbonate (CaCO3), which will react chemically with the acid, causing it to deteriorate or erode. This happens because the acid causes the calcium (Ca) and carbonate (CO3) in the limestone to separate into calcium and carbon dioxide gas (CO2).
Although the lemon juice and vinegar acids used in this activity are actually more concentrated than acid rain, they successfully demonstrate the erosive effects of acid rain over time.
Before the lesson
With the students
Attachments (Return to Contents)
Safety Issues (Return to Contents)
Students should not eat or drink any of the liquid or other materials used during activity.
If using nails, remind students to use them ONLY for carving their chalk; they should not poke or scratch their classmates, tabletops or walls.
Troubleshooting Tips (Return to Contents)
If necessary, the tip of a ballpoint pen or pencil may be used instead of nails to carve into the piece of chalk; please keep in mind, however, that it may ruin the writing implement.
What should happen: The chalk in the lemon juice and vinegar should dissolve such that students should not be able to see their pictures. If this does not happen:
Assessment (Return to Contents)
Discussion Questions: Solicit, integrate and summarize student responses.
Know / Want to Know / Learn (KWL) Chart: Before the lesson, ask students to write down on their Acid KWL Chart (or in the top left corner of a piece of paper or as a group on the board) under the title, Know, all the things they know about acid rain. Next, in the top right corner under the title, Want to Know, ask students to write down anything they want to know about acid rain. After the lesson, ask students to list in the bottom half of the page under the title, Learned, all of the things that they have learned about acid rain. Ask students to name a few items and write them on the board.
Activity Embedded Assessment
Prediction: Have the students predict what will happen when they put their chalk into the liquid and record predictions on their worksheet.
Attack Worksheet: Have the students complete the activity worksheet; review their answers to gauge their mastery of the subject.
Question/Answer: Ask the students and discuss as a class:
Know / Want to Know / Learn (KWL) Chart: Finish the remaining section of the KWL Chart as described in the Pre-Lesson Assessment section. After the lesson, ask students to list in the bottom half of the page under the title, Learned, all of the things that they have learned about acid rain. Ask students to name a few items and write them on the board.
Activity Extensions (Return to Contents)
Extend the activity by leaving the chalk in the containers of liquid and wait a few days to see when/if the chalk completely dissolves. Students can record how many days it took the chalk to dissolve for each liquid and make a representative line graph of the data. This simulates the effect of acid rain over a longer period of time. Try adding other items to the liquid, such as leaves, metals or plastic.
Try other common acids and bases and see what affect they have on chalk, leaves or other common items. For example, use cola (acid) or oven cleaner (base).
Make a flyer or poster about why engineers care about acid rain. For example, students can express that acid rain damages building, car paint and ecosystems. Have students draw a picture of something an engineer could do to help reduce acid rain.
References (Return to Contents)
McGee, Elaine. U.S. Department of the Interior, U.S. Geological Survey, "Acid Rain and Our Nation's Capitol," July 21, 1997, accessed August 5, 2006. http://pubs.usgs.gov/gip/acidrain/
ContributorsJessica Todd, Melissa Straten, Malinda Schaefer Zarske, Janet Yowell
Copyright© 2006 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.