SIDE DISPLAY
Acid Rain Eats Stone!
Visitors drip sulfuric acid onto one piece of chalk and water
onto another piece of chalk and observe the results.
OBJECTIVES:
Visitors learn the composition of acid rain. They learn how acid
rain can react with and affect certain structures.
SCIENCE TOPICS
PROCESS SKILLS
VOCABULARY
Chemical Reactions
Observing
Acid
Environmental Pollutants
Investigating
Chemical Reaction
Controlling Variables
Pollutant
Unit 4 Environmental Chemistry
Experiencing Chemistry ©1997 OMSI
U4.57
Acid Rain Eats Stone!
To do and notice:
1. Create a fresh surface on a piece of chalk by
rubbing it on one of the stone bunnies
2. Squeeze 1 drop of sulfuric acid solution
(H2SO4) onto the piece of chalk
3. Squeeze 1 drop of water (H2O) onto
another piece of chalk that has been
roughed up.
4. Watch both drops carefully. Use the
magnifying glass to look closely.
Which drop reacts with the surface of the chalk and begins to
bubble?
What is going on?
Acid rain is composed primarily of dilute sulfuric acid (H2SO4)
and dilute nitric acid (HN03). These acids are formed from the
gases sulfur dioxide (S02) and nitrogen dioxide (NO2). Both
gases are pollutants emitted by smokestacks and tailpipes.
Acid rain affects both living and nonliving things. Chalk,
concrete, and marble contain calcium carbonate (CaCO3).
When either of the two acids comes in contact with calcium
carbonate, it reacts to form carbon dioxide (CO2), water (H2O),
and a salt. The bubbles you see are carbon dioxide gas. The
simulated acid rain will gradually cause the chalk to crumble
into the gravel. The concrete bunnies show what happens to a
statue exposed to acid rain.
©2007 OMSI
U4.58
Unit 4 Environmental Chemistry
Experiencing Chemistry ©1997 OMSI
Side Display: Acid Rain Eats Stone!
See Materials Prep
for more details
Operating Guide
(with amounts to have on hand)

Two 30-ml dropper bottles

One 9 x 12-inch Pyrex baking dish

One large, resealable plastic storage bag

Two small concrete bunnies or other animal statues (available at a
garden supply store)

Several small pieces of blackboard chalk (keep one box on hand)

15-20 ml 1M H2SO4(sulfuric acid) (keep 200 ml on hand)
—OR— 28 ml 18M (concentrated) H2SO4(keep 100 ml on hand)

One 100-ml graduated cylinder

One 500-ml plastic bottle

One 600-ml beaker

One glass stirring rod
Setup/Takedown Procedures
 Fill the baking dish with one inch of gravel or sand.
 Place the bunnies on top of the gravel, toward the back of the dish.
 Break two or three chalk pieces in half and place them on the gravel,
near the front of the dish.
 Label the two 30-ml dropper bottles “Water (H2O)” and “1M (Sulfuric
Acid (H2SO4).”
 Fill the dropper bottles with the appropriate solutions.
 Set out the dish, dropper bottles, and public copy.
 Replace the chalk pieces as needed.
 Refill and relabel the dropper bottles as needed.
 This setup can be reused indefinitely. At the end of the week, return it
to Unit 4 storage.
Unit 4 Environmental Chemistry
Experiencing Chemistry ©1997 OMSI
U4.59
Side Display: Acid Rain Eats Stone!
◊
Operating Guide
In time, after reacting with sulfuric acid, the concrete bunnies will form
a layer of CaSO4 (calcium sulfate). If a visitor then tries to drop acid
onto the bunnies, the reaction will not be obvious. You can explain
this by describing the protective layering and add that the acid is still
doing damage—just at a slower rate.
You can relate this to what happens with marble buildings or statues
when they are exposed to acid rain.
H2SO4 (sulfuric acid) is a hazardous substance; follow the handling
and disposal instructions.
Consult the Material Safety Data Sheets (MSDS) for additional
information.
CAUTION: Concentrated (18M) H2SO4 (sulfuric acid) is extremely
corrosive. Handle it with care. Wear protective gloves, an apron,
and eyewear. Use it only in the fume hood. Avoid contact with
skin or clothing. Neutralize any spills with baking soda and clean
up with large amounts of water.
CAUTION: A large amount of heat will be evolved after you mix
the H2SO4 with water. Do not handle the beaker until it has
cooled.
To make 1M H2SO4 (sulfuric acid):
 Turn on the fume hood.
 Wear protective eyewear, chemical safety gloves, and an apron or lab
jacket.
 Fill the 600-ml flask with 472 ml of dH2O (deionized water) and place it
in the fume hood.
 In the fume hood, measure 28 ml of concentrated (18M) H2SO4
(sulfuric acid) into a 100-ml graduated cylinder.
 SLOWLY add the acid to the water and stir the solution with a glass
rod
 Store the solution in a labeled/dated 500-ml plastic bottle in the acid
cabinet.
 Turn off the fume hood.
U4.60
Unit 4 Environmental Chemistry
Experiencing Chemistry ©1997 OMSI