CHEMISTRY IN CONTEXT
LAB #18 – ACID AIN SIMULATION, PAGE 1
NOVEMBER 29, 2006
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Acid Rain Simulation
An Application of Acid-Base Principles
PRE-LAB/DISCUSSION:
Acid Rain and Acid Deposition
By now, you had exposure through lecture notes to one of the applications of acid and base
principles, namely acid deposition also known as acid rain. It is often referred to ac acid
deposition because the acid can take the form of liquid (as rain) or solid (as sleet or snow) and
even gas (as fog). Contrary to popular belief, acid rain does not eat away at and burn the skin of
people who are caught in acid rainfall. However, it can slowly and detrimentally effect many
aspects of human structures and the environment.
Acid rain can deteriorate structures such as buildings and statues as the acids in the rain
neutralize the basic stone substances and turn them into a weak salt and water. As well, acid can
change the pH of water sources like lakes and ponds causing them to be unable to host life.
Therefore, it destroys habitat. Finally, acid rain can change the pH of soils, especially those at
high elevations, making the soils acidic and killing the trees and plants that need the life-giving
soil
Air Pollution
Acid rain is caused by air pollution.
The gases that we emit from the
combustion of gasoline and coal lead to
acid rain. Air pollution is a tricky issue
to deal with because even though one
state, country, or area may have rules
about pollutants, air pollutants can
travel and affect other areas with acid
rain. For example, the Great Smoky
Mountains of western North Carolina
have been experiencing acid deposition
for many years. The Great Smokies are
a national park; therefore, the air pollutants are not coming from inside the park. Instead, the air
pollution travels from areas such as Ohio and Pennsylvania and settles over the snokies. The
picture above is testament to the effects of acid rain on trees on the top of Mt. Mitchell.
CHEMISTRY IN CONTEXT
LAB #18 – ACID AIN SIMULATION, PAGE 2
NOVEMBER 29, 2006
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Today, you will be simulating how the pollutants that cause acid rain can travel using an
indicator solution. The indicator solution appears one color in the presence of a neutral
substance and quite a different color in the presence of acids and bases. Thankfully, in Kentucky
our limestone deposits help to buffer the effects of acid rain by neutralizing it.
Some safety reminders:
1)
You will be using concentrated sulfuric acid today. It IS one of the strongest acids
that we have at TLS. Be VERY careful! Report any spills immediately and use
baking soda if you believe that you have spilled some or been exposed.
2)
You will observe STANDARD PRECAUTIONS today.
3)
The indicator solutions act as dyes and may stain skin and clothing.
APPARATUS/MATERIALS:
1 microplate (looks like a well plate but with MANY small compartments)
sulfuric acid
pulverized calcium carbonate powder (simulating Kentucky limestone)
water
1 dropper bottle of phenol red indicator
(appears yellow in acids and red/pink in neutrals and bases
plastic pipette
250mL beaker
plastic zip sandwich bag
scoopula/spatula
50mL beaker
PROCEDURE:
1)
Acquire a well plate, rinse it with water, turn it upside down, and “pop” the back of it
to cause all the water to fall out.
2)
Half fill your 250mL beaker with tap water.
3)
Notice the numbers and letters down the sides of the well plate. They create a grid.
Use your pipette and beaker of water to HALF FILL ALL of the small holes in the
microplate with water EXCEPT the following wells:
A1, A2, A3, A4
B1, B2, B3, B4
C1, C2, C3, C4
F10, F11, F12
G10, G11, G12
H10, H11, H12
4)
Use your scoopula/spatula to fill your 50mL beaker to the 10mL mark with
pulverized calcium carbonate powder.
CHEMISTRY IN CONTEXT
LAB #18 – ACID AIN SIMULATION, PAGE 3
NOVEMBER 29, 2006
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Use your scoopula/spatula to half fill the following wells with the powder
F10, F11, F12
G10, G11, G12
H10, H11, H12
Then, take your microplate to the main lab bench and use the pipette that is already in
the concentrated sulfuric acid to half fill the following wells/holes with concentrated
sulfuric acid:
A1, A2, A3, A4
B1, B2, B3, B4
C1, C2, C3, C4
Acquire a dropper bottle of phenol red indicator. Place one drop of phenol red into
EACH of the wells in your well plate. Use the tip of your water pipette to carefully
mix the phenol red with the calcium carbonate ONLY. It will look cloudy pink.
Make a note of the colors on your well plate in your Data/Observations section.
Then, carefully slide the plate into the sandwich bag and seal the bag. This bag will
simulate the earth. There is acid rain pollution on one small part of the earth’s
surface. Let’s see how it affects the REST of the globe.
Let your experiment run inside the sandwich bag until about 5-8 minutes before the
end of class (watch the clock!). Watch and record the changes in color in your
microplate about every two minutes.
When you are finished, rinse your microplate and pop the back to release the water.
Return all materials to their appropriate locations.
DATA/OBSERVATIONS:
TIME
Before
Inside
Sandwich
Bag
COLOR CHANGES
CHEMISTRY IN CONTEXT
LAB #18 – ACID AIN SIMULATION, PAGE 4
NOVEMBER 29, 2006
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ANALYSIS:
1)
According to your notes, which acids are responsible for acid rain or acid deposition?
2)
Did your microplate change colors as time progressed? Why? Which well or hole
CAUSED the change?
3)
The calcium carbonate simulated Kentucky’s limestone. What color did it change? Why
did it not change the same colors as the water wells/holes?
4)
Use google.com to find information on how Kentucky deals with air pollution OR acid
rain. Describe what you found in the space below.