Acid Rain Learning About - A Teacher's Guide For Grades 6 Through 8
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Learning About
Acid Rain
A Teacher’s Guide
For Grades 6
Through 8
United States Environmental Protection Agency Office of Air and Radiation Office of Atmospheric Programs Clean Air Markets Division (6204J) 1200 Pennsylvania Ave., NW Washington, D.C. 20460 EPA 430-F-08-002 April 2008
1970 – 1994
1970 1970 1977
Twenty million people The Clean Air Congress strengthens
celebrate the first Act (CAA) the CAA and includes
Earth Day. is passed. requirements for SO2
pollution control at
power plants.
1978 1980
The National Atmospheric Deposition Program/National The National Acid Precipitation
Trends Network (NADP/NTN) begins monitoring sulfur Assessment Program (NAPAP),
and nitrogen deposition to ecosystems. mandated by Congress, begins
study on acid rain.
1980 1986 1987
Lake acidification and fish The United States and Canada begin The Clean Air Status
loss in the Adirondacks, study of cross-border acid rain and Trends Network
Green Mountains, and Sierra transport. The United States is called (CASTNET) is
Nevada make national news. upon to reduce emissions of SO2 and established to
NOX, especially from coal-burning monitor dry
power plants. deposition.
1990 1993 1994
Congress strengthens the CAA and EPA publishes acid rain Projected costs of compliance
establishes the Acid Rain Program regulations, and the re-estimated by the
using a market-based approach to Chicago Board of Trade Government Accountability
reduce SO2 from power plants by holds first auction of Office and the Electric Power
more than 50 percent. SO2 allowances. Research Institute at less than
half of original estimates.
1995 – 1999 2000 – 2005
1995 2000
Phase I of Acid Rain Program implementation Phase II of Acid Rain Program
begins. SO2 emissions fall to 5 million tons begins, regulating additional
below 1980 levels. Acidity of rainfall in the smaller/cleaner plants and
eastern United States drops 10 to 25 percent. requiring further reductions
in NOx and SO2.
1996 2001 2002
About 150 of the largest Introduction of the EPA begins electronic
coal-fired power plants On-line Allowance audit process to
begin to implement Acid Tracking System supplement existing
Rain Program NOx begins an era of rigorous monitoring
requirements. paperless allowance program.
transfer recording.
1997 2003 2004
More than 80 Lakes and streams in Acid Rain Program sources
percent of affected the Adirondacks, Upper emit 34 percent less SO2
companies have Midwest, and Northern and 43 percent less NOx
engaged in private Appalachian Plateau than in 1990, despite a
allowance show signs of recovery. 34 percent increase in
transactions. fuel usage.
1998 1999 2005
Regulatory revisions Allowance New study estimates 2010 annual Acid Rain
enhance efficiencies of banking peaks. Program benefits at $122 billion and annual
compliance and SO2 early reduc- costs at $3 billion. According to the 2005 NAPAP
administration. Nearly tions total over report, further emission reductions are neces-
10 million economically 11 million tons. sary to achieve broader environmental recovery.
significant allowance EPA promulgates Clean Air Rules to further
transfers take place. reduce SO2, NOx, and for the first time, mercury.
4
Contents
PURPOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
OBSERVATIONS ABOUT ACIDITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
DEFINING ACID RAIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 .
Air Pollution Causes Acid Rain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 .
Acid Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 .
Dry Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 .
Acid Rain Is A Problem That Can Travel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 .
Natural Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
EFFECTS OF ACID RAIN ON ECOSYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 .
Forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 .
Acid Rain On The Forest Floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 .
Ponds, Lakes, And Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
EFFECTS OF ACID RAIN-CAUSING POLLUTANTS ON HUMANS . . . . . . . . . . . . . . . . . . . . . 12
EFFECTS OF ACID RAIN ON MAN-MADE MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . 13
WHAT IS BEING DONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
The Acid Rain Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Alternative Ways Of Producing Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
What You Can Do To Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
To Prevent Acid Rain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
To Address Other Environmental Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
EXPERIMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Measuring With pH Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Measuring With pH Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Safety In The Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Recording Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Experiment 1: Measuring pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Experiment 2: Determining The pH Of Common Substances . . . . . . . . . . . . . . . 24
Experiment 3: Making A Natural pH Indicator . . . . . . . . . . . . . . . . . . . . . . . . . 25
Experiment 4: Measuring The pH Of Natural Water . . . . . . . . . . . . . . . . . . . . . . 26
Experiment 5: Measuring Soil pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Experiment 6: Soil Buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Experiment 7: Observing The Influence Of Acid Rain On Plant Growth . . . . . . . . 29
Experiment 8: Looking At Acid’s Effects On Metals . . . . . . . . . . . . . . . . . . . . . . 30
Experiment 9: Observing The Influence Of Acid Rain On Marble And Limestone . 31
Experiment ANSWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
ACTIVITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Games . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Crossword Puzzle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Word Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Game Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Participation and Completion Certificate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
1
Purpose
Acid rain is a complex environmental site (www.epa.gov). EPA frequently
problem which affects the United States receives requests for information about
and many other countries around the environmental problems from school
world. The United States Environmental systems, teachers, and individuals. Acid
Protection Agency (EPA) was established rain is one of the most frequently
in 1970 to address environmental issues, requested topics. As part of EPA’s public
such as acid rain. Through its programs, outreach on acid rain, EPA first devel-
EPA works to protect human health and oped this guide in 1990. This revised
the environment in the United States by guide is designed to help students
developing and enforcing regulations better understand the science, cause
and studying environmental conditions. and effect, and regulatory and citizen
action that are part of understanding
In addition, EPA is committed to inform- and addressing acid rain.
ing the public about environmental
topics and its efforts to solve them This book is intended for teachers of
through written materials and its Web students in 6th-8th grade. It is written at
a 6th grade level and the language,
concepts, and experiments may need to
be adapted for other grades accordingly.
After reading the guide and doing some
of the experiments and activities, we
hope that you and your students will
have a better understanding of acid rain
and the problems it causes, as well as a
greater interest in its resolution and in
applied environmental science.
In addition to this teacher’s guide, EPA
has many other publications with
information on research, monitoring,
regulation, and other aspects of the acid
rain problem. If you are interested in
learning more, resources are available at
www.epa.gov/airmarkets. This guide,
“Learning About Acid Rain: A Teacher’s
Guide for Grades 6 Through 8,” is avail-
able online at www.epa.gov/acidrain
/education/teachersguide.pdf. Printed
copies are available for free through the
Acid Rain Hotline (202-343-9620).
2
Introduction
from. Natural resources that humans use T erminology
to generate electricity are called ENERGY
Natural Resources All the parts of
RESOURCES. Most energy in the United the Earth that are not human-made
States comes from burning FOSSIL FUELS and which people use, like fish,
such as coal, oil, and natural gas. Coal, trees, minerals, lakes, or rivers.
oil, and natural gas are called fossil fuels Energy Resources Natural
because they were formed millions of resources that can be used to
make heat, electricity, or any
years ago from dead plants and animals. other form of energy. The most
commonly used energy resources
People burn fossil fuels for many are fossil fuels (coal, oil, and
gas), but the sun, wind, and
reasons. We burn oil and coal to make anything else that makes energy
the electricity that we need to light are also energy resources.
buildings and run appliances like televi-
Fossil Fuels Oil, natural gas, and
sions and computers. We burn gas to coal. Fossil fuels were made
heat our homes and to power cars, in nature from ancient plants
and animals, and today we
buses, and airplanes. Many human burn them to make energy.
activities, including the burning of fossil
Pollution The release of harmful
fuels, cause POLLUTION. Pollution is the substances into the environment.
release of harmful substances called
Pollutants Chemicals or
pollutants into the ENVIRONMENT. other substances that are
The air pollution created when fossil harmful to or unwanted in the
fuels burn does not stay in the air environment. Some examples
When harmful substances are released into of pollutants are sulfur dioxide
the air, it causes pollution. forever. Instead it can travel great (SO2), nitrogen oxides (NOx),
distances, and fall to the ground again ozone, and particulate matter.
as dust or rain. When airborne chemi- Environment The air, water,
Humans make use of many things found
cals and pollutants fall to the Earth, soil, minerals, organisms, and
in nature. For example, we use trees to all other factors surrounding
or deposit, it is called DEPOSITION.
build our homes and cotton to make our and affecting an organism.
clothes. Things that are not made by ACID RAIN forms when clean rain comes Deposition When chemicals
people, but instead occur naturally, are into contact with pollutants in the air, like acids or bases fall to the
Earth’s surface. Deposition can
called NATURAL RESOURCES. Some like SULFUR DIOXIDE (SO2), CARBON be wet (rain, sleet, snow, fog)
examples of natural resources are DIOXIDE (CO2), and NITROGEN OXIDES or dry (gases, particles).
plants, minerals, and water. All of these (NOX). Although sulfur dioxide and Acid Rain Rain that has become
things are important to humans because carbon dioxide occur in the air natu- acidic by contact with air pollution.
they provide us with the materials we rally, burning fossil fuels adds more of Other forms of precipitation,
such as snow and fog, are also
need to make the things we use every- these chemicals to the air. When these often included in the term acid
day. Some of the products made from pollutants are released into the air, rain or acid wet deposition.
natural resources are obvious to us, like they mix and react with water, oxygen, Sulfur Dioxide (SO2) A naturally
the timber and stone that make build- and other chemicals to form acid occurring gas made of sulfur
and oxygen that is also released
ings. Other natural resources are not as rain. Acid rain then falls to the Earth when fossil fuels are burned.
noticeable, like the underground water where it can damage plants, animals,
table where our drinking water comes soil, water, and building materials.
3
T erminology Despite its name, acid rain does not Earth’s temperature to rise. For more
burn and cannot directly harm people. information on climate change and its
Carbon Dioxide (CO2) A naturally
occurring gas made of carbon However, the pollutants that cause acid causes and effects, check out
and oxygen. Sources of carbon rain, especially SO2 and NOX, can react www.epa.gov/climatechange.
dioxide in the atmosphere with other pollutants in the air, forming
include animals, which exhale The consequences of air pollution are
carbon dioxide, and the burning substances like Particulate Matter and
of fossil fuels and biomass. ground level Ozone, which can some- important to understand because air
times make people sick. pollution can be carried long distances
Nitrogen Oxides (NOx) A family
of gases made up of nitrogen and affect large areas. This means that
and oxygen commonly released While the “Acid Rain Teacher’s Guide” pollution from a town hundreds of miles
by burning fossil fuels. focuses mainly on the issue of acid rain, away may be affecting your community.
Particulate Matter Tiny solid the EMISSIONS that result from the Scientists, engineers, and researchers
particles or liquid droplets burning of fossil fuels have many other monitor the effects of pollution on the air,
suspended in the air.
environmental consequences in addition forests, water, and soil. They are invent-
Ozone A chemical that is made to causing acid rain. Chemicals like NOX, ing ways to reduce the amount of
of three oxygen atoms joined
together, and found in the Earth’s produced by the burning of fossil fuels, pollution that enters the environment
atmosphere. There are two kinds combine with other chemicals in the and to prevent new damage in the future.
of ozone: good ozone, and bad atmosphere to form ground level ozone.
ozone. Good ozone is found
high in the Earth’s atmosphere, Although the planet needs an ozone
and prevents the sun’s harmful layer for protection from the sun’s
rays from reaching the Earth.
harmful ultraviolet rays, ozone can be Where Our Electricity
Bad ozone is found low to the
ground, and can be harmful to dangerous when it forms low to the Comes From
animals and humans because it ground because it hurts our lungs and
damages our lungs, sometimes
making it difficult to breathe. sometimes makes it difficult to breathe.
Emissions The gases that Other chemicals that are released by the
are released when fossil /THER %NERGY 0ETROLEUM
burning of fossil fuels are GREENHOUSE 3OURCES
fuels are burned.
GASES. Greenhouse gases occur naturally
Ozone Layer The layer of ozone
that shields the Earth from
in the Earth’s atmosphere, keeping the
the sun’s harmful rays. planet warm enough for humans to live.
Without greenhouse gases, the planet .UCLEAR
Greenhouse Gases Gases that occur
naturally in the Earth’s atmosphere would be an average 60° F colder than it
and trap heat to keep the planet is today (brrr!). However, since the #OAL
warm. Some examples are carbon
dioxide, water vapor, halogenated Industrial Revolution, human activity,
fluorocarbons, methane, such as the burning of fossil fuels, has .ATURAL 'AS
hydrofluorocarbons, nitrous increased the amount of greenhouse
oxide, perfluoronated carbons,
and ozone. Some human actions, gases in the atmosphere. By increasing
like the burning of fossil fuels, (YDROELECTRIC
the levels of greenhouse gases, human
also produce greenhouse gases.
activities are affecting the mix of gases
in the atmosphere. This is causing the
Half of our electricity in the United States is
made by coal power plants.
4Observations About Acidity
ACIDIC and BASIC are two extremes that Pure water is neutral. However, when T er m in o l o g y
describe chemicals, just as hot and cold chemicals are mixed with water, the
Acidic Describes a substance
are two extremes that describe tempera- mixture can become either acidic or with a pH less than 7.
ture. Mixing ACIDS and BASES can cancel basic. Examples of acidic substances are
Basic Describes a substance with
out their extreme effects; much like vinegar and lemon juice. Laundry a pH greater than 7. Another
mixing hot and cold water can even out detergents and ammonia are examples word for basic is alkaline.
the water temperature. A substance that of basic substances. Chemicals that are
Acid Any of a large group of
is neither acidic nor basic is NEUTRAL. very basic or very acidic usually change chemicals with a pH less than
The pH SCALE measures the acidic or or alter whatever they meet. Substances 7. Examples are battery acid,
lemon juice, and vinegar.
basic level of a substance. The pH scale that have this property are called
ranges from 0 to 14. A pH of 7 is neutral, REACTIVE. You should be careful with Base Any of a large group
of chemicals with a pH
while a pH less than 7 is acidic and a pH these kinds of chemicals because they greater than 7. Examples are
greater than 7 is basic. can cause severe burns and are often ammonia and baking soda.
toxic if swallowed. For example, house-
Neutral A substance that is
hold drain cleaners often contain lye, a neither an acid nor a base
very basic chemical that is reactive and and has a pH of 7. Neutral
substances can be created by
could burn you. combining acids and bases.
The pH Scale
pH Scale The range of units that
indicate whether a substance
is acidic, basic, or neutral. The
pH scale ranges from 0 to 14.
"ATTERY !CID Reactive Having the tendency
!CID 2AIN to chemically combine with
,EMON *UICE something else and change its
form. For example, a strong acid is
6INEGAR !DULT &ISH $IE highly reactive with a strong base.
#OLA
&ISH 2EPRODUCTION !FFECTED
)NCREASINGLY
#OFFEE
!CIDIC .ORMAL 2ANGE OF 0RECIPITATION
-ILK
.EUTRAL 7ATER .EUTRAL .ORMAL 2ANGE OF 3TREAM 7ATER
Try Thes
Experim e
)NCREASINGLY
"AKING 3ODA
"ASIC
3EA 7ATER
Expe
ents!
3OAP rim
Measuri ent 1
ng pH
Experim p.23
Determinent 2
in
Commo g the pH of
!MMONIA n Substa
Experim nces
p.24
,YE Making ent 3
a
pH Indic Natural
ator
p.25
5Defining Acid Rain
T erminology Acid rain is rain that is more acidic than need to do all kinds of things, like light
it should be. Acid rain is a complicated our homes. Cars, trucks, and airplanes
Atmosphere The air or gases
that surround a planetary problem affecting soil and water chemis- also run on gasoline, a fossil fuel.
body such as the Earth. try, as well as the life cycles of plants
When we burn things, they do not
and animals on land and in the water. In
Sulfuric Acid An acid that can be disappear. For example, when you burn
produced in the atmosphere from addition, weather conditions contribute a log in a campfire, ash is left. But what
sulfur dioxide, a pollutant that to air pollution and cause acid rain to
results from burning fossil fuels. happened to the rest of the log? Water
spread vast distances. from the log becomes vapor and enters
Nitric Acid An acid that can be
produced from nitrogen oxide,
the air. Burning wood also releases
a pollutant that results from chemicals and particles into the air. The
the burning of fossil fuels. Air Pollution Causes same thing happens when we burn
Precipitation Water falling to Acid Rain fossil fuels. Burning fossil fuels sends
the Earth. Mist, sleet, rain, hail, smoke and fumes into the ATMOSPHERE,
fog, and snow are the most Scientists have discovered that air or the air above the Earth. In the air,
common kinds of precipitation.
pollution from the burning of fossil fuels these pollutants combine with moisture
Hydrologic Cycle The movement of is the major cause of acid rain. Power to form acid rain. The main chemicals in
water from the atmosphere to the air pollution that create acid rain are
surface of the land, soil, and plants plants and factories burn coal, oil, and
and back again to the atmosphere. natural gas to produce the electricity we sulfur dioxide (SO2) and nitrogen oxides
(NOX). Acid rain usually forms high in the
clouds where SO2 and NOX react with
Hydrologic Cycle water and oxygen. This forms SULFURIC
ACID and NITRIC ACID in the atmosphere.
Sunlight increases the speed of these
reactions, and therefore the amount of
acid in the atmosphere. Rainwater,
Condensation snow, fog, and other forms of
Precipitation as PRECIPITATION then mix with the sulfuric
Rain, Snow, Hail, Fog
and nitric acids in the air and fall to
Earth as acid rain.
Acid Precipitation
Evaporation from
Lakes, Rivers, Oceans
Runoff Water moves through the air, streams,
lakes, oceans, and every living plant and
animal in the HYDROLOGIC CYCLE, shown
in the image to the left. In that cycle,
water evaporates from the land and sea
and becomes a gas in the atmosphere.
Water in the atmosphere then
CONDENSES, or becomes liquid again,
6T erminology
Evaporate To change
from liquid into gas.
Condense To change from gas
or vapor to liquid form.
Dry Deposition The falling of
small particles and gases to the
Earth without rain or snow.
Runoff Water that flows off
land into lakes and streams.
Acid Deposition Acidic material
Tall smokestacks send pollution high into the air. The longer the pollution is in the air, the
that falls from the atmosphere
greater the chances that the pollutants will form acid rain. to the Earth in either wet
(rain, sleet, snow, fog) or dry
and forms clouds. Clouds release the particles can damage or alter the things (gases, particles) forms.
water back to the Earth as rain, sleet, on which they settle. Dry deposition
hail, snow, or fog. When water droplets (gases and particles) is sometimes
form and fall to the Earth they pick up washed from trees and other surfaces
particles like the dust and chemicals by rainstorms. When that happens, the
that float in the air. Even clean, unpol- RUNOFF water contains acid from acid
luted air contains particles such as dust rain and dry deposition, making the
or pollen. Clean air also contains natu- combination more acidic than the falling
rally occurring gases such as carbon rain alone. The combination of acid rain
dioxide (CO2). The interaction between (wet deposition) plus dry deposition is
the water droplets and the CO2 in the called acid deposition.
atmosphere gives rain a pH of 5.6,
making even clean rain slightly acidic.
However, when rain contains pollutants, Acid Rain Is A
especially SO2 and NOX, the rainwater can
become very acidic.
Problem That Dry deposition can be washed
Can Travel away from surfaces such as
buildings and cars during
rainstorms.
Dry Deposition The chemical reactions that cause acid
rain can take several hours to several
Acid rain does not account for all of days to occur. Years ago, when smoke-
the acidity that falls back to Earth from stacks were only a few stories high, Try This
pollutants. About half of the acidity in pollution from smokestacks usually Experim
the atmosphere is deposited onto stayed near the ground and settled on
Expe
ent!
the land nearby. This caused unhealthy rimen
buildings, cars, homes, and trees— Measuri t 4
ng the p
anything!—as particles and gases. This conditions for people, plants, and Of Natu
ral Wate
H
animals near those smokestacks. To r
process is called DRY DEPOSITION. In p.26
some instances, these gases and reduce this pollution, the government
7passed laws for the construction of very
tall smokestacks. At that time, people
Natural Acids
thought that if the pollution were sent There are also natural sources of acids
high into the air it would no longer be a such as volcanoes, geysers, and hot
problem. Scientists now know that this springs. Nature has developed ways of
is incorrect. In fact, sending pollution recycling these acids by absorbing and
high into the sky increases the time that breaking them down. These natural
the pollution stays in the air. The longer acids contribute to only a small portion
the pollution is in the air, the greater the of the acidic rainfall in the world today.
chances that the pollutants will form In small amounts, these acids actually
acid rain. In addition, the wind can carry help dissolve nutrients and minerals
these pollutants for hundreds of miles from the soil so that trees and other
before they become joined with water plants can use them for food.
droplets to form acid rain. For that Unfortunately, the large amounts of
reason, acid rain, or wet deposition, can acids produced by human activities
be a problem in areas far from sources overload this natural acidity and throw
Volcanoes are a natural of pollution. Dry deposition is usually ecosystems off balance.
source of acid. greater near the cities and industrial
areas where the pollutants are released.
Formation of Acid Rain
A geyser, like the one shown
here in Yellowstone National
Park, is also a natural source
of acid.
8Effects Of Acid Rain On Ecosystems
Acid rain and the air pollution that
causes it can severely damage
ECOSYSTEMS. An ecosystem is all the
living and nonliving things in an area, as
well as the interactions between them.
Ecosystems come in all sizes. An entire
forest is an ecosystem, but so is a single
tree. Some scientists even consider the
entire Earth an ecosystem. The study of
ecosystems is called ECOLOGY. Ecologists
study things like predator-prey relation-
ships, how nutrients are taken from the
soil into trees, or the kinds of bacteria Sugar Maple leaves turn brilliant shades of red, orange, and yellow in the fall.
found in a pond. Every ecosystem is People from all over the United States and the world travel to New England to see
colorful autumn leaves like those of the Sugar Maple.
very interconnected, and the organisms
that live there rely heavily on each
other. For example, ecosystems have
are important to ecosystems because T erminology
they feed everything else, and provide
food webs, where species depend on Ecosystem All the living and
important HABITAT for other animals. If nonliving things in an area, as well
one another for food. If any one animal
trees and plants are damaged by acid as the interactions between them.
is affected, so are several others. This is
rain, the effects are felt throughout the Ecology The study of ecosystems.
how acid rain can affect entire ecosys-
entire ecosystem. Someone who studies ecology
tems. Acid rain may only damage a few is called an ecologist.
organisms in an ecosystem, but every- Acid rain causes trees in forests to grow
Primary Producers Organisms
thing else is indirectly affected. The more slowly, and in some sensitive that use photosynthesis to
damage acid rain causes can also take species it can even make the leaves or produce their own food. All
plants are primary producers.
years, or even decades to reverse. needles turn brown and fall off. Red Primary producers are the
Spruce and Sugar Maple, two species of base of the food chain because
trees found mainly in the East and in they feed everything else.
Forests New England, are very susceptible to Photosynthesis The process that
acid rain damage. Acid rain damages plants use to convert sunlight
Acid rain causes significant damage to to energy to live and grow.
trees by dissolving the calcium in the
forests. It directly affects trees and other soil and in the leaves of trees. This hurts Habitat The place where a plant
plants which are important to the or animal lives and grows, such
the tree, because calcium is a mineral as a forest, lake, or stream.
ecosystem as a whole because they are that trees need to grow. Once the
PRIMARY PRODUCERS. Primary producers Nutrient Deficiency When a living
calcium is dissolved, the rain washes it thing lacks the vitamins and
are organisms that produce their own away so the trees and other plants minerals it needs to survive.
food through PHOTOSYNTHESIS, a series cannot use it to grow. Acid rain washes
of chemical reactions that convert water other minerals and nutrients from the
into sugar using light from the sun to soil in a similar fashion, causing
provide energy. Plants and some micro- Nutrient Deficiency. This is why acid
scopic animals have this ability. Plants rain can cause trees to grow more slowly.
9T erminology rain can cause problems with the move-
ment of nutrients to other organisms in
Aluminum A silvery-white
metal; it is the most abundant ecosystems that are already impacted.
metal in the Earth’s crust.
Further reducing the amount of photosyn-
Haze When particles of dust,
pollen, or pollution make the air
thesis are acid fogs. Fog can often be
less clear, and limit visibility. more acidic than rainfall. When leaves are
Neutralize To combine acids
frequently bathed in acid fog, their
and bases to make a neutral protective waxy coating can wear away.
substance or solution. For The loss of this coating damages the
example, acidic water can be
neutralized by adding a base. leaves and creates brown spots. The
Rain falls through the trees to the forest floor leaves are then unable to use photosyn-
Buffering Capacity The ability of a
substance to resist changes in pH
and runs into streams, rivers, and lakes. thesis to turn the energy in sunlight into
when acids or bases are added. food for growth. When leaves are
Buffer A substance, such as soil, Nutrient deficiency causes other prob- damaged, they cannot produce enough
bedrock, or water, capable of lems for trees and plants. The lack of food energy for the tree to remain healthy.
neutralizing either acids or bases.
nutrients weakens the trees, and makes
them more sensitive to the cold. A
well-nourished tree in healthy soil will Acid Rain On The
survive even a very cold winter with Forest Floor
little difficulty, but a tree already weak-
ened by a mineral deficiency can die A spring shower in the forest washes
during a cold winter. The weakened leaves and the rain falls through the
trees and plants are also more sensitive trees to the forest floor below. Some of
to insects and disease. the water soaks into the soil. Some
trickles over the ground and runs into a
At the same time, acid rain causes
stream, river, or lake. Soil sometimes
the release of substances such as
contains substances, like limestone, that
aluminum from the soil. Aluminum can
buffer acids or bases. Some salts in soil
be very harmful to trees and plants.
may also act as buffers. The soil may
Once released into soil, aluminum can
NEUTRALIZE, or make less acidic, the acid
Try Themse end up in streams, rivers, and lakes,
eri e nts! where it can harm or even kill fish. Less
rainwater. This ability of the soil to resist
Exp aluminum is released when the rainfall
pH change is called BUFFERING CAPACITY.
A BUFFER resists changes in pH. Without
ent 5 p.27 is cleaner.
Experim g Soil pH buffering capacity, soil pH would change
rin
Measu
ent 6 p.28 The pollution that causes acid rain also rapidly. Midwestern states like Nebraska
Experim ering
Soil B u ff causes HAZE by scattering light back and Indiana have soils that are well
ent 7 towards the sky. Haze reduces the buffered. Places in the mountainous
Experim g the
Obse rv in
e of Acid p.29 amount of light available for plants to northeast, like New York’s Adirondack
Influenc Plant Growth
Ra in o n use in photosynthesis. Since photosyn- Mountains, have soils that are less able
thesis is the base of the food chain, acid to buffer acids. Other soils, like those in
10the Southern Appalachian Region, hold down) when the rainwater itself is so
acids from acid rain, making them more acidic that the surrounding soil cannot
susceptible to damage from acid rain. buffer the rain enough to neutralize it.
Since there are many natural sources of For this reason, some lakes in areas
acids in forest soils, soils in forest areas where soil does not have a lot of
are especially sensitive to effects from buffering capacity are naturally acidic
acid rain. even without acid rain. In areas like the
northeastern United States where soil
buffering is poor, acid rain has made
Ponds, Lakes, already slightly acidic lakes very acidic,
And Streams with some lakes having a pH value of
less than 5. As lakes and streams
The effects of acid rain are most clearly become more acidic, the numbers and
seen in AQUATIC environments such as types of fish and other aquatic plants
streams, lakes, and marshes. Acid rain and animals that live in these waters
Snails have a very low pH
flows to streams, lakes, and marshes decrease. Some types of plants and
tolerance of 6.0.
after falling on forests, fields, buildings, animals are able to tolerate acidic
and roads. Acid rain also falls directly on waters. Others, however, are acid-sensi-
tive and will leave or die as the pH T erminology
aquatic habitats.
declines. Some acidic lakes have no fish, Aquatic Relating to water.
Most lakes and streams have a pH because at pH 5 most fish eggs cannot
between 6 and 8, because the buffering hatch. At lower pH levels, adult fish can
capacity of soil usually neutralizes die. Substances like aluminum that wash
slightly acidic, clean rain. Lakes and into the water from the soil can also
streams become acidic (pH value goes harm and kill fish.
Some animals can survive
in water that is moderately
pH Tolerance Chart on Aquatic Life acidic, while other animals
can only live in water that is
pH 6.5 pH 6.0 pH 5.5 pH 5.0 pH 4.5 pH 4.0 near neutral. An animal that
Trout can survive in moderately
acidic water is said to have a
Bass
high tolerance for acidity. The
Perch chart to the left shows the pH
tolerance of various animals.
Frogs Where the boxes are gray,
Salamanders the animals can survive, but
where the boxes are black, the
Clams animals can no longer tolerate
Crayfish the acidity and die. From the
chart, you can see that frogs
Snails have a high tolerance for
Mayfly acidity, while clams and snails
have a low tolerance.
11Effects Of Acid Rain-Causing
Pollutants On Humans
T erminology
Respiratory Illness Diseases
affecting the organs we use to
breathe. Asthma, bronchitis,
and pneumonia are examples
of respiratory illnesses.
Respiratory System The organs
in our body involved with
the process of breathing.
These are photos from the Great Smoky Mountains National Park in Tennessee and
North Carolina. The photo on the left, taken January 21, 1986, shows what the park
looks like on a clear day, or a day where there is little pollution present to reduce
visibility. The photo on the right, taken August 5, 1986, shows the same view on a
hazy day, when the air is filled with aerosols.
Acid rain looks, feels, and tastes just infections. Even healthy people can have
like clean rain. Walking in acid rain, or symptoms related to ozone exposure,
even swimming in an acid lake, is no including coughing, pain with deep
more dangerous for humans than breathing, chest tightness, and short-
walking or swimming in clean water. ness of breath. Over time, ozone can
However, breathing air that contains the cause permanent damage to the lungs
pollutants that cause acid rain can or even death. Small particles called
damage human health. Sulfur dioxide particulate matter are made up of the
(SO2), nitrogen oxides (NOx), particulate same pollutants that cause acid rain.
matter, and ozone all irritate or even Particulate matter also damages the
damage our lungs. These effects are lungs. The tiny particles of dust that
mostly seen in people whose lungs have make up particulate matter can bypass
already been weakened by respiratory the body’s natural defenses and become
illness, but even healthy people can lodged deep in the lungs, where it can
sometimes have pain or difficulty cause irritation and damage the lungs.
breathing because of air pollution.
SO2 and NOX, the pollutants that cause
Ozone is a dangerous pollutant that is acid rain, can also reduce visibility,
caused by air pollution, especially in the limiting how far into the distance we can
summer. Exposure to high levels of see. These pollutants form small parti-
ozone have been linked to a number of cles in the atmosphere. These particles
health problems. Ozone can make reduce visibility by scattering light.
respiratory illnesses, such as asthma, Reduced visibility is most noticeable in
Air pollution, shown here emphysema, and bronchitis worse. places like National Parks, where people
in New York City, can cause Ozone can also reduce the respiratory go to see some of the nation’s most
health problems. system’s ability to fight off bacterial beautiful landscapes.
12Effects Of Acid Rain
On Man-Made Materials
Acid rain eats away at stone, metal, dissolved by acids. Calcium carbonate How Acid Rain Affects
paint—almost any material exposed to is also found in limestone. Many build- Stonework
the weather for a long period of time. ings and monuments are made of
Human-made materials gradually marble and limestone and are damaged
deteriorate even when exposed to by acid rain. Repairing acid rain damage
unpolluted rain, but acid rain speeds up to buildings and monuments can cost
the process. Acid rain can rust metals billions of dollars. Historical monuments
and cause marble statues carved long and buildings, such as the Lincoln
ago to lose their features. This happens Memorial in Washington, D.C., can
because marble is made of a compound never be replaced.
called calcium carbonate, which can be
How Acid Rain Affects Metal
The picture on the top was taken
The Lincoln Memorial in Washington, D.C. in 1908. The picture on the
bottom was taken in 1968.
Try Thes
Experim e
Expe
ents!
rim
Looking ent 8
Effects o at Acid’s
n Metals
Experim p.30
Observinent 9
Of Acid g the Influence
R
And Lim ain on Marble
estone
p.31
13What Is Being Done
EPA has been working with Congress and By the year 2010, power plants must
other federal government agencies; reduce emissions of these pollutants by
state, local, and tribal governments; about 50 percent from levels in 1980.
scientists; and citizens to solve the acid Today, power plants emit 35 percent less
rain problem for over 15 years. SO2 and 46 percent less NOx than they did
in 1990.
The Acid Rain Program is so successful
The Acid Rain because it uses a CAP AND TRADE
Program program to reduce emissions. A cap and
trade program is a policy that controls
The Acid Rain Program was established large amounts of emissions from a
by Congress as part of the 1990 Clean Air group of sources. The approach first sets
The Rockport Power Plant in
Rockport, Indiana, burns coal Act Amendments. It requires the electric an overall cap, or maximum amount of
to produce electricity. power industry to lower emissions of emissions allowed, for all pollution
sulfur dioxide (SO2) and nitrogen oxides sources under the program. The cap is
T erminology (NOx), the pollutants that cause acid rain. chosen in order to meet an
Cap and Trade An environmental
policy tool that controls large
amounts of emissions from a Cap and Trade
group of sources. Cap and trade
programs set a cap, or limit, on Initial Emissions
emissions. Then allowances for Total = 30 tons
emissions are traded between
sources, so that economic market 10 tons 10 tons 10 tons
Allowable Limit (Cap)
forces allow large emissions Cap Total = 15 tons
reductions to be cost-effective. 7 tons
5 tons
3 tons
Cap A national limit that is placed
on the amount of a pollutant
that can be emitted. The cap
is very important because it
makes sure that emissions of
a pollutant are reduced.
Plant A Plant B Plant C
Reduction: 5 tons Reduction: 7 tons Reduction: 3 tons
2 Allowances
All three plants were required to reduce their emissions from 10 tons to 5 tons each. Plant A
reduced its emissions by 5 tons to meet the cap and be in compliance. Plant B reduced its
emissions to 3 tons, 2 tons more than were required. Plant C only reduced its emissions to
7 tons. This is not enough to cover its allowances and be in compliance. In a cap and trade
program, Plant B can sell its two extra allowances to Plant C. Plant C can then use the two
allowances it bought to cover its emissions and stay under its cap.
Notice that even though a trade took place, overall emissions for Plants A, B, and C are within
the cap (5 + 3 + 7 = 15). Total emissions in this cap and trade system are half of what they
used to be (30 tons vs. 15 tons).
14environmental goal. In this case the cap the Acid Rain Program because the strict T erminology
is the maximum level of SO2 and NOx penalties discourage power plants from
Allowance The permission, given
emissions that all power plants not having enough allowances. In fact, by the government, to emit a
combined can emit. Allowances, or in 2006, the Acid Rain Program had certain amount of sulfur dioxide
permits to pollute a specific amount, are (SO2) or nitrogen oxide (NOx).
100 percent compliance from sources
then given to power plants. It is up to of emissions. Scrubber A device that removes
the individual power plants to decide air pollution, mainly sulfur
dioxide, from smokestacks.
how they want to lower their emissions, Power plants can reduce the amount of
but the total amount of emissions from pollution they produce in several ways.
all power plants across the country must Some plants choose to wash the sulfur
be less than the cap. If one source out of coal before it is burned. There are
reduces their emissions far below the also different kinds of coal and some
amount assigned to them, they are have less sulfur and nitrogen in them.
allowed to sell their leftover emission Pollutants can also be removed from the
allowances to another power plant that
smoke as it travels through the smoke-
did not reduce their emissions enough.
stack. A device called a SCRUBBER
The option of selling extra emission
removes sulfur from the smoke by
allowances to make money is an incen-
spraying a mixture of water and
tive for the power plants to reduce their
emissions even more than required. powdered limestone into the smoke-
Companies that do not reduce their stack. This mixture traps the sulfur
emissions enough and emit more before it can escape into the air above.
pollution than they have allowances for, There are also several other ways to
must buy allowances to cover their decrease the pollution coming from
emissions or face heavy fines and other power plants and scientists and engi-
strict penalties. This rarely happens in neers are always discovering new ones.
Wet Acid Deposition, 1989-1991 Wet Acid Deposition, 2003-2005
Source: CASTNET Source: CASTNET
These maps show how the Acid Rain Program has reduced the amount of wet acid deposition (acid rain) in the United States.
In these maps, the dark areas represent places with high amounts of acid rain. Notice how the areas with lots of acid rain in
1989–1991 have shrunk since the Acid Rain Program started.
15T erminology Cap and trade is most effective when the emissions of SO2 and NOX in the eastern
environmental or public health issue United States even further than the Acid
Atmospheric Relating to the
atmosphere, or the air above occurs over a large area, when there are Rain Program.
the Earth. many sources of pollution which contrib-
To learn more about cap and trade, go to
Meteorological Pertaining to ute to the problem, when emissions can
the Clean Air Markets cap and trade Web
the weather. be monitored, and when there is variety
site at www.epa.gov/airmarkets/cap-trade/.
in the amount of money that sources
If you want to know more about the other
must pay to reduce their emissions.
A CASTNET cap and trade programs, like the NOx
Monitoring Site A mandatory cap on emissions is critical Budget Trading program or CAIR, go to the
to protect public health and the environ- Clean Air Markets program Web site at
ment. The Acid Rain Program and the www.epa.gov/airmarkets.
NOX Budget Trading Program have been
very effective in reducing emissions of
SO2 and NOX. Though long-term environ-
Monitoring
mental monitoring has proven that these How does EPA know its programs are
programs are working, studies have working? Experts from EPA, states,
shown that more reductions in emis- universities, and other agencies have set
sions are necessary to protect human up air quality and deposition monitoring
health and the environment. In 2009, a stations across the country. These
new program called the Clean Air monitoring stations contain equipment
Interstate Rule (CAIR) will begin. This that constantly collects air quality data
program will lower power plant and samples. These devices measure
many things, including the amount of
CASTNET Monitoring Stations pollution in the air, the pH of rain, the
amount of rainfall, and the surrounding
temperature. There are several networks
made up of many stations taking
samples in different areas. The Clean Air
Status and Trends Network (CASTNET)
takes samples from mostly rural areas
around the United States. CASTNET
measures dry deposition and collects
atmospheric data. The National
Atmospheric Deposition Program (NADP)
has sites around the United States and
focuses on precipitation and
meteorological monitoring. By using
this information, EPA is able to track the
success of the Acid Rain Program and
other cap and trade programs by linking
CASTNET now has over 80 monitoring stations across the United States.
16reductions in emissions to improvements
in air quality. You can see these monitor-
Alternative Ways Of
ing stations and the information they Producing Energy
collect online at http://camddataandmaps
There are other sources of energy
.epa.gov/gdm/.
besides fossil fuels. These include
EPA also requires power plants to use hydroelectric power, wind power,
Continuous Emissions Monitoring NUCLEAR POWER, solar power, and fuel
Systems (CEMS) to keep track of the cells. Hydroelectric dams use the power
amount of pollution they release into of water to turn TURBINES and make
the air. A CEMS is a monitoring device electricity. Windmills work the same way
that each unit must place on their but instead, use wind to turn the
smokestack. These monitors take turbines. People have been using wind
samples of the air traveling through the and water power for centuries. Nuclear
smokestack, and measure the amount of power plants collect the energy released
Solar Power: Solar panels
pollutants traveling through it. Then, the by splitting tiny atoms apart inside
produce electricity.
monitor sends the recordings to EPA. nuclear reactors. Although nuclear power
CEMS allows EPA to keep track of plants generate dangerous waste that
emissions to make sure that the power must be disposed of carefully, a small
companies are following the laws to amount of nuclear fuel can make a very T erminology
reduce pollution. large amount of electricity. Some people
Hydroelectric Power Energy that
also use solar power, or power from the is generated by dams, which
sun, to make electricity. Some houses use water to turn turbines
use solar power to heat water for and generate electricity.
showers, and even some traffic signs Wind Power Energy that is
run off of solar panels. Fuel cells are generated when the wind
turns the sails of a windmill,
similar to batteries, except that fuel cells which are attached to turbines
run on oxygen and hydrogen. They use that generate electricity.
chemical reactions to generate electric- Nuclear Power Energy that
ity, and produce water as a waste. comes from breaking apart the
center (nucleus) of an atom.
All sources of energy have benefits and
Solar Power Electricity that
limitations, including the cost of produc- is generated by harnessing
ing the energy. All of these factors must the energy of the sun. Solar
panels are often used to
be weighed when deciding which energy convert sunlight into energy.
source to use.
Fuel Cells Similar to batteries,
fuel cells store energy that can be
used to power all sorts of things.
Unlike a battery though, fuel cells
do not “run out” and do not need
to be recharged or replaced.
Turbine A motor activated by water,
steam, or air to produce energy.
Wind Power: Windmills produce electricity.
17What You Can Do To Help
All environmental problems, including furnaces, etc. For more information,
acid rain, are caused or impacted by the see EPA’s Energy Star® Web site
combined actions of individual people. www.energystar.gov.
This is why individuals can play a big
part in solving these problems. While you 3. You can greatly reduce acid rain-caus-
cannot run a nationwide cap and trade ing emissions (especially NOX emissions)
program from your classroom, there are by changing your transportation habits.
many things you can do to help reduce Try to reduce the amount of time you
pollution and protect the environment. spend in the car by walking, biking, or
taking public transportation. When you
drive, plan trips ahead of time to
To Prevent Acid Rain minimize miles traveled, drive the most
fuel-efficient car you can, and carpool
1. Conserve electricity by turning off whenever possible. The EPA publishes a
lights, appliances, and computers when green vehicle guide at www.epa.gov
no one is using them. /greenvehicles/.
2. Join ENERGY STAR®’s “Change a Light, 4. Shrink your “carbon footprint” and
Change the World” program and pledge reduce greenhouse gas emissions by
to use energy-efficient light bulbs in turning the thermostat down a little bit in
your home. This will reduce the amount winter, or up a little bit in the summer.
of energy you use, and in turn reduce New technologies can also greatly
the amount of emissions produced by increase the efficiency of your heating
power plants. You can also lower your and air conditioning and other
energy consumption by using other appliances. Look for the Energy Star®
Energy Star® products and appliances, Label. EPA provides information about
including TVs, computers, refrigerators, some of these technologies and other
washing machines, air conditioners, ways to reduce greenhouse gas emissions
at www.epa.gov/climatechange/wycd.
Taking public transportation can help reduce acid rain-causing emissions.
18To Address Other
Environmental
Problems
1. Volunteer to help clean up trash and
litter in local streams and rivers, or help
restore wetlands. By cleaning up trash,
you help protect ecosystems that are
important habitats to wildlife. Information
about wetland restoration efforts in your
area can be found in the restoration
project directory at www.epa.gov/owow
/wetlands/restore/.
2. Recycle everything you can at home
and if your school does not already have
a recycling program, start one! This
reduces the amount of waste that you
produce, and keeps recyclable materials
out of landfills. Also, try to buy products
Recycling at home is a great way to keep recyclable materials out of landfills.
with less packaging, or products with
recyclable packaging. More information
about recycling and waste reduction
programs can be found at EPA’s solid 4. Try talking to your school’s principal
waste education Web site, www.epa.gov or superintendent about ways to reduce
/epaoswer/education. the impacts your school has on the
environment. There are many small
3. Many areas of the United States, things your school can do to help
especially the Southwest, have problems protect ecosystems. For some ideas,
with water availability. Conserving water check out http://cfpub.epa.gov/schools.
helps ecosystems and the people and
animals that live in them. You can help 5. Spread the word! Share what you
by reducing the amount of water you have learned about Acid Rain and other
use by taking shorter showers, or environmental problems with others. Tell
turning off the faucet while brushing them what they can do to protect the
your teeth. Learn more by visiting the environment. The more information
EPA’s Water Sense page at www.epa.gov people have, the more they can do to
/owm/water-efficiency. make the Earth a cleaner, healthier place.
19Experiments
pH Paper
When measuring pH with pH paper or
litmus paper, dip the end of a strip of
the paper into each mixture you want
to test. Follow the directions on the
package regarding how long you need
to keep the pH paper in the mixture
and how long to wait before reading
the measurement. Then compare the
color at the wet end of the paper with
the color chart provided with that pH
indicator. Write down the pH value and
color. Always use a clean, unused strip
of pH paper for each mixture that you
test. Be sure to conduct the pH test for
T erminology The answers to all of the questions in each substance three times, using a
the experiments section can be found new pH paper for each test. Record the
Litmus Paper Paper coated with a
chemical coloring obtained from at the end of the section, on page 33. results of each test. If possible, have
lichens that turns red in acidic
water and blue in basic water. It a different student conduct and record
each test. This helps to ensure scientific
Measuring With
is used as an acid-base indicator.
pH Paper Paper that changes color accuracy, consistency, and replicability.
to show the pH of a substance. pH Paper
For most of the following experiments, Measuring With
you will need a pH indicator. A pH indi-
cator contains a chemical that changes pH Meters
color when it is exposed to acids or
A pH meter provides a more precise pH
bases. For example, LITMUS and pH
measurement than pH paper. Before
PAPER turn red in strong acids and blue
using a pH meter, rinse the electrode
in strong bases. Because only a few
with distilled water and blot dry with a
pH indicators measure pH over a wide
range of pH values, you will need to find clean paper towel. Calibrate the meter
out the pH range of the indicator you according to the directions. When testing
use. Typically, the color chart provided the pH of a substance, put the electrode
with each pH indicator kit will show tip in the mixture and stir once. Be sure
the pH range of that indicator. Color pH not to touch the bottom or sides of the
indicators provide only an approximate container. Hold the electrode in the
measure of the pH, or the strength mixture for 1 minute or until the reading
of the acid or base. They are not as is steady. Record the measurement and
accurate as pH meters, but they are repeat the test two more times for
adequate for the following experiments. accuracy and consistency.
20For more information on measuring • Lemon juice and white vinegar are both
the pH of soil and water, check out acids. You may substitute fresh-
the pH protocols defined by GLOBE squeezed lemon juice for white vinegar.
(Global Learning and Observations Lemon juice is slightly more acidic than
to Benefit the Environment) at the vinegar sold in grocery stores. White
www.globe.gov/protocols. vinegar is preferred over cider vinegar
or lemon juice because it is colorless
and relatively free of impurities.
Tips
• Use clean, dry containers and utensils.
• Except for wide-range pH test paper
and pH meters, all the materials called
for in these experiments can be Safety In The
obtained at grocery stores or from local
lawn and garden stores or nurseries. Laboratory
• Wide-range pH test paper is pH paper A science or chemistry laboratory can
that covers the whole pH scale. Not all and should be a safe place to perform
pH test papers do this. Other papers experiments. Accidents can be prevented
cover only part of the pH scale and if you think about what you are doing at
there are different papers to test for all times, use good judgment, observe
acids, bases, and neutrals. Both kinds safety rules, and follow directions.
are inexpensive, and a school science
laboratory will probably have one or
the other, if not both. If the school
does not already have pH test paper a
science teacher may know where to
order it, or you may order it on your
own through a biological supply
company. If you have to order pH test
paper, we recommend wide range pH
test paper since it can be used for all
the experiments, and may be less
confusing to younger students.
• Baking soda and ammonia are both
bases. You may substitute baking soda
for household ammonia in the experi-
ments. If you do, be sure to stir well
because baking soda does not dissolve
easily in water unless heated. The pH
of undissolved baking soda will not be
the same as dissolved baking soda. Always wear protective safety glasses or goggles when working on experiments.
21• Eye protection (goggles or safety • Dispose of all chemicals properly,
glasses) must be worn when working according to the directions of your
on experiments. Make a habit of teacher.
putting them on before the experiment
• If you spill any acid or base material
begins and keeping them on until all
on you, wash the exposed area with
clean up is finished.
large amounts of cold water. If skin
• Do not eat or drink while in the becomes irritated, see a physician.
laboratory.
• Do not taste any chemical. Recording
• Long-sleeved shirts and closed-toe, Observations
leather-topped shoes must be worn at
all times. Writing your observations on these
experiments will help you to keep
• Long hair must be tied back, so it will better track of the progress of the
not fall into chemicals or flames. experiment and help you to remember
information for answering questions or
• Do not work alone; work with an adult.
Writing down your observations writing lab reports. Record keeping can
can be very helpful. • Never perform any unauthorized be very simple and still be a help. These
experiment. hints can help you organize and record
your thoughts.
• All glassware must be washed and
cleaned. Wipe all counter surfaces and • Use a bound notebook so that pages
hands with soap and water. are not lost.
• All experiments that produce or use • Write complete sentences for all
chemicals must be done in a well- written entries.
ventilated area.
• Use drawings as needed.
• Never point the open end of a test
• Date each entry (even drawings).
tube at yourself or another person.
• Use the title of the experiment as your
• If you want to smell a substance, do
first entry.
not hold it directly to your nose.
Instead, hold the container a few • When your observation entries have
centimeters away and use your hand been completed, write your answers
to fan vapors toward you. to the questions that follow each
experiment.
• When diluting acids, always add the
acid to the water; never water to acid. • Write your own thoughts about the
Add the acid slowly. experiment as the conclusion.
22You can also read
