Peggy travels
                                                             to the
                                                             Wolf Ridge 
                                                             Learning Center
                                                             to learn about 
                                                             acid rain.


What causes acid rain?


Acid rain is considered by many people to be one of the most serious environmental problems of our time. It is a global problem that is gradually affecting our world. The term acid rain was coined by Angus Smith when he wrote about industrial pollution in England.

Some rain is naturally acidic because of the carbon dioxide (CO2) in air that dissolves with rain water and forms a weak acid. This kind of acid in rain is actually beneficial because it helps dissolves minerals in the soil that both plants and animals need.

Recently there has been some concern that the acidity of rain caused by man has increased over the last several decades. Acid rain attacks wildlife, crops and lakes. It can cause the death of forests and damage buildings and monuments. It is even harmful for human beings.

Acid rain is caused by pollution. Pollutants like sulphur dioxide and nitrogen oxide stay in the atmosphere and eventually react with the moisture in the air. When this polluted moisture falls to the ground, it is called acid rain. The source of these pollutants is not only from burning fossil fuels, but from both motor vehicle and chemical manufacturing exhaust.

Sulphur dioxide is unlike other kinds of acid pollution because it does not react with moisture until it has been taken long distances by the wind. Even worse is that rain and snow are not the only ways the environment can be damaged by air pollution. Dry fallout from sulphur dioxide can still affect the environment.

Although places like the Adirondacks in New York have been seriously damaged because the lime in their soil is so easily dissolved by acid rain, there are ways to bring it under control. When both the United States and Canada began reducing the amount of sulphur dioxide released into the air, fresh water lakes and ponds in parts of Canada showed some improvement.

Things to Talk About

  1. Have you seen examples of acid rain damage in your area? What other parts of the world have been affected by it? Are any other governments dealing with the problem?
  2. How could you help stop acid rain?

Acid--A substance that has a pH less than 7.0.

Acid Rain--The popular term used for wet and dry acid deposition.

Base--A substance with a pH of more than 7.0.

Ecology--The study of the relationships of living things to one another and to their environment.

Environment--The aggregate of surrounding things, conditions or influences.

Indicator--A substance such as litmus that shows whether a solution is an acid or a base.

Snert--Acid snow.

pH Scale--A logarithmic scale (ranging from 0-14) that measures acidity.


Activity Page

Take the Litmus Test!

With a simple test you can discover what acids you use everyday.

Main Activity

Using a special kind of paper called litmus paper, you will test some common solutions. Litmus or pH paper is an indicator paper that turns different colors depending how acidic or basic a solution is.


1. Put 250 ml of water in each glass or jar. Label the jars A, B, C and D.

2. Add 10 ml of lemon juice in A; 10 ml of ammonia in B; one gram of baking soda to C, and 10 ml of cola to D.

3. Dip a separate piece of litmus paper into each container. Compare your results to the color chart included with your litmus paper.


1. Were you surprised by the pH level of the cola? What about the ammonia?

2. Can you name other acidic solutions? What about base or alkali solutions?

3. What happens if you mix an acid and a base together? What does the litmus paper look like?

Try This!
Compare the ingredients on the labels of various antacids. Do they have any common ingredients? Are these products acids or bases? When do you use these products? What other acids and bases are found in medicine?

Try This!
Put a piece of chalk into a jar of vinegar. Observe what happens to the chalk. Put a piece of limestone into another jar of vinegar. What happens to the liquid? Are any gasses being released? Could acid rain have the same effect on buildings and roadways?

Try This!
Watch the newspapers for two weeks and clip out any articles on air, water or land pollution. What are people doing about these environmental problems? If this is a global issue, how can everyone work together to help the environment? What can you do?

Try This!
Choose three of the same size and type of plant for an experiment. Make sure that they are in the same size pots and have equal amounts of sunshine and liquid. Over a one to two week period, water plant A with just water, plant B with water and lemon juice and plant C with water and baking soda. Record your observations. Which plant looks the healthiest? Is there any damage to the plant that received baking soda?

Tapes of this episode of Newton's Apple and others are available from GPN for only $24.95.
Please call 1-800-228-4630.
For information on other Newton's Apple resources for home and school,
please call 1-800-588-NEWTON!


Newton's Apple is a production of KTCA Twin Cities Public Television. Made possible by a grant from 3M.

Educational materials developed with the National Science Teachers Association.

PBS Online - Minnesota Online - Welcome to Newton's Apple - Teacher's Guides Index