Acid Rain
Acid Rain
Introduction
Journals and Snapshots
The Snapshot button is used to capture the
screen.
The Journal is where snapshots are stored
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The Share button is used to export
or print your journal to turn in your
work.
Each page of this lab that
contains the symbol
should be inserted into your
journal. After completing a
lab page with the snapshot
symbol, tap
(in the
upper right hand corner) to
insert the page into your
journal.
Note: You may want to take a
snapshot of the first page of
this lab as a cover page for
your Journal.
Acid Rain
Lab Challenge
• What makes normal rain into "acid rain"?
• What causes this phenomena and how does it relate to the chemical
concept of pH?
Acid Rain
Background
• Acid rain is a form of precipitation with an unusually low pH. The acidity
causes harmful effects on the environment and living systems.
• Pollution is a primary cause of acid rain. Harmful gases produced during the
burning of fossil fuels (particularly coal) interact with water in the air to form
acids that become part of the precipitation.
• pH is a measurement of the concentration of hydrogen ions [H+] in water. pH
values can range from 0 through 14. The lower the pH, the higher the
concentration of hydrogen ions and the more acidic a substance is. A pH of 7 is
neutral—neither acidic nor basic. pH values greater than 7 are considered
basic.
Acid Rain
Self-Check
1. Acid rain is rainwater with an unusually low
______________.
a) particle count
b) base
c) volume
d) pH
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to take a snapshot
of the page after you have
entered your response.
Acid Rain
Background
• Acid rain causes the pH of lakes and streams to drop, killing some organisms
in those environments, especially smaller organisms. Acid rain can also harm
plants and other terrestrial organisms by lowering the pH of the soil.
• Acid rain accelerates the decay of building materials (such as limestone and
marble), metals (such as bronze), automotive paint, and other coatings.
• The harmful pollutant gases that cause acid rain can also lower the visibility of
air and make the air less healthy to breathe.
Acid Rain
Self-Check
2. Acid rain causes the ______ of lakes to drop and
can even make statues slowly _______.
a) rise: pollute
b) pH : dissolve
c) temperature : freeze
d) number : rust
Acid Rain
Safety
• Use all standard laboratory safety procedures.
• Do not let the hydrochloric acid (HCl) touch your skin or clothes.
• The glass pipette used to transfer HCl is fragile. Handle with care.
• Do not remove the rubber stopper from the Erlenmeyer flask once
reactions have started.
• Dispose of solutions down the drain with excess water.
• After completing the lab, wash your hands with soap and water.
Acid Rain
Materials and Equipment
Collect all of these materials before beginning the lab.
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•
•
•
•
pH sensor
Erlenmeyer flask, 100 mL (3)
1-hole rubber stopper for flask (3)
Glass tubing for rubber stopper
Flexible tubing to fit glass tubing, 20
cm
• Beaker, 100 mL
• Graduated cylinder, 25 mL
• Graduated pipette and pipette bulb
•
•
•
•
•
•
•
Sodium bicarbonate (NaHCO3), 5 g
Sodium bisulfite (NaHSO3), 5 g
Sodium nitrite (NaNO2), 1.5 g
1 M HCl, 15 mL
Glycerin
Water or deionized water, 60 mL
Wash bottle containing distilled or
deionized water
• Balance
Acid Rain
Sequencing Challenge
A. Determine the
initial pH of a
sample of distilled
water.
B. Assemble the gas
generator.
C. Bubble CO2 into
the sample of
distilled water while
measuring pH.
D. Bubble NO2 into a
sample of distilled
water while
measuring pH.
E. Bubble SO4 into a
sample of distilled
water while
measuring pH.
The steps to the left are part
of the procedure for this lab
activity. They are not in the
right order. Determine the
correct sequence of the steps,
then take a snapshot of this
page.
Acid Rain
Overview
In this lab, 3 gases will be created: CO2, NO2, and SO2. Once the gases are created,
they will be bubbled through water to see how they affect pH.
• Sodium bicarbonate (NaHCO3) with hydrochloric acid (HCl) to produce carbon
dioxide gas (CO2).
• Sodium nitrite (NaNO2) with hydrochloric acid (HCl) to produce nitrogen
dioxide (NO2).
• Sodium bisulfite (NaHSO3) with hydrochloric acid (HCl) to produce sulfur
dioxide gas (SO2).
Acid Rain
Setup: General
1. Connect a pH sensor to the data collection system.
2. Measure 20.0 mL of distilled water using a graduated cylinder.
3. Pour the water into the 100 mL beaker.
4. Thoroughly rinse the pH electrode with distilled water.
5. Place the rinsed pH electrode in the beaker.
Acid Rain
Prediction: General
Q1: What do you think will happen to the pH of the water when you dissolve these
gases in it? Which gas will produce the largest change in pH?
Acid Rain
Setup/Collect Data: CO2 (g) and Water
1. Obtain a sample of powdered sodium bicarbonate (NaHCO3)
from the teacher.
2. Measure 5 grams of NaHCO3.
3. Place the measured NaHCO3 in the Erlenmeyer flask.
Acid Rain
Setup/Collect Data: CO2 (g) and Water
4. Assemble the flask, stopper, glass tubing or
barbed connector, and flexible tubing.
Use glycerin to
lubricate the
connection
Note: If necessary, use glycerin to lubricate the
connections between flexible tubing, glass connector,
and rubber stopper.
5. Add 4 mL of 1.0 M hydrochloric acid (HCl) into
the Erlenmeyer flask and immediately stopper
the flask.
Caution: Hydrochloric acid is a strong acid. Handle with
care. Flush any spillage with a lot of water.
Erlenmeyer flask
pH sensor
Acid Rain
6. Place the free end of the
flexible tubing in the
water in the beaker.
Immediately tap
to
begin recording data.
7. Record data for ~200
seconds or until the pH
stabilizes. Then tap
to
stop recording.
Acid Rain
Q2:What is happening to the
pH of the water as you
bubble CO2 into it?
Acid Rain
8. Determine the minimum
and maximum pH* for the
CO2 run and record these
values in the data table on
the next page.
* To Find the X- and Y-Values
of a Data Point:
1. Tap
to open the tools
palette.
2. Tap
and then tap a data
point.
3. Tap or to select
nearby data points.
Acid Rain
9. Record the minimum and
maximum pH values in
the data table.*
*To Enter Data into a Table:
1. Tap
to open the tool
palette.
2. Tap
then tap a cell in
the data table to highlight it
in yellow.
3. Tap
to open the
Keyboard screen.
Acid Rain
Setup/Collect Data: NO2 (g) and Water
1. Dispose of the contents in the flask and beaker from the previous trial, as
directed by your teacher.
2. Thoroughly rinse the pH sensor electrode using the wash bottle.
3. Rinse the beaker and tubing with water.
4. Measure 20.0 mL of distilled water (not tap water) using a graduated
cylinder.
5. Pour the water into the 40-mL beaker.
6. Thoroughly rinse the pH electrode with distilled water (not tap water).
7. Place the rinsed pH electrode in the beaker.
Acid Rain
Setup/Collect Data: NO2 (g) and Water
8. Measure 5 g sodium nitrite (NaNO2).
9. Place the measured NaNO2 into a clean Erlenmeyer flask.
10.Reassemble the flask, stopper, glass tubing or barbed connector, and flexible
tubing (same as for CO2 run).
11.Add 4 mL of 1.0 M hydrochloric acid (HCl) into the Erlenmeyer flask and
immediately stopper the flask.
Acid Rain
12. Place the free end of the
flexible tubing in the
water in the beaker.
Immediately tap
to begin recording data.
13. Record data for ~200
seconds or until the pH
stabilizes. Then tap
to
stop recording.
Acid Rain
14. Determine the minimum
and maximum pH* for the
NO2 run and record these
values in the data table on
the next page.
* To Find the X- and Y-Values
of a Data Point:
1. Tap
to open the tools
palette.
2. Tap
and then tap a
data point.
3. Tap or to select
nearby data points.
Acid Rain
15. Record the minimum and
maximum pH values in
the data table.*
*To Enter Data into a Table:
1. Tap
to open the tools
palette.
2. Tap
then tap a cell in
the data table to highlight
it in yellow.
3. Tap
to open the
Keyboard screen.
Acid Rain
Setup/Collect Data: SO2 (g) and Water
1. Dispose of the contents in the flask and beaker from the previous trial as
directed by your teacher.
2. Thoroughly rinse the pH sensor electrode using the wash bottle.
3. Rinse the beaker, flask, and tubing with water.
4. Measure 20.0 mL of distilled water (not tap water) using a graduated
cylinder.
5. Pour the water into the 40-mL beaker.
6. Thoroughly rinse the pH electrode with distilled water (not tap water).
7. Place the rinsed pH electrode in the beaker.
Acid Rain
Setup/Collect Data: SO2 (g) and Water
8. Measure 5 g sodium bisulfite (NaHSO3)
9. Place the measured NaHSO3 into a clean Erlenmeyer flask.
10.Reassemble the flask, stopper, glass tubing or barbed connector, and flexible
tubing (same as previous runs).
11.Add 4 mL of 1.0 M hydrochloric acid (HCl) into the Erlenmeyer flask and
immediately stopper the flask.
Acid Rain
12. Place the free end of the
flexible tubing in the water
in the beaker. Immediately
tap
to begin recording
data.
13. Record data for ~200
seconds or until the pH
stabilizes. Then tap
to
stop recording.
Acid Rain
14. Record the minimum and
maximum pH values in the
data table.*
15. Calculate the change in pH
for each run and record
your data in the table.
*To Enter Data into a Table:
1. Tap
to open the tool
palette.
2. Tap
then tap a cell in
the data table to highlight
it in yellow.
3. Tap
to open the
Keyboard screen.
Acid Rain
Clean up
1. Dispose of the contents of the flask and beaker from the previous trial as
directed by your teacher.
2. Thoroughly rinse the pH sensor electrode using the wash bottle.
3. Rinse the beaker, flask, and tubing with water.
Acid Rain
Analysis
1. In an ideal graph of these experiments, the pH change should be dramatic
initially and then eventually level off. Why does this occur?
Acid Rain
Analysis
2. Compare the change in pH for each type of gas tested. Which showed
the greatest and least change in pH? Based on this information,
which gas is worst for the environment?
Acid Rain
Analysis
3. In the three reactions of gas dissolving in water, what caused the reduced
pH of the water?
Acid Rain
Synthesis
1. Which of the gases in this experiment is a man-made pollution that causes
acid rain? What are some important sources of these gases?
Acid Rain
Synthesis
2. Coal from states in the western United States, like Montana and Wyoming, has
a lower percentage of sulfur impurities than coal found in the eastern United
States. How would burning low-sulfur coal change acid rain?
Acid Rain
Synthesis
3. What are some ways to treat the effects of acid rain?
Acid Rain
Synthesis
4. What are some ways to PREVENT the formation of acid rain?
Acid Rain
Synthesis
5. Although carbonic acid produces only a small decrease in pH of water, why is it
of concern in the environment?
Acid Rain
Multiple Choice
1. Which of the following is true about acid rain?
a) Acid rain is linked to NO2 and SO2 molecules in
the atmosphere.
b) Acid rain can result in the death of many
species of water-dwelling organisms when it
causes the pH of lakes to decrease to a level
outside their tolerance.
c) Acid rain affects soil chemistry and the ability
of plant roots to take in nutrients.
d) All of the above are true.
Acid Rain
Multiple Choice
2. Which of the following play an important role
in the formation of acid rain?
a) gases in the atmosphere
b) buffers in soils and water
c) water in the atmosphere
d) A and C
Acid Rain
Multiple Choice
3. In general, rain exerts harmful effects on ecosystems
when it falls below a pH of _______.
a) 3.6
b) 4.6
c) 5.6
d) 6.6
Acid Rain
Multiple Choice
4. Acid rain has been linked to which of the
following?
a) Damage to fish through reactions that
create high aluminum concentrations in the
water.
b) Reduced nutrient uptake by tree roots.
c) Weakening trees, so they become more
susceptible to other types of damage.
d) All of the above.
Acid Rain
Congratulations!
You have completed the lab.
Please remember to follow your teacher's instructions for cleaning-up and submitting
your lab.
Acid Rain
References
Images are taken from PASCO documentation, public domain clip art, or Wikimedia Foundation Commons
http://www.flickr.com/photos/buddharhubarb/21865208/
http://commons.wikimedia.org/wiki/File:Acid_rain_woods1.JPG
http://commons.wikimedia.org/wiki/File:BrownSoil.jpg
http://commons.wikimedia.org/wiki/File:FoggDam-NT.jpg
http://commons.wikimedia.org/wiki/File:Ham_Pond.jpg
http://commons.wikimedia.org/wiki/File:Sixfinger_threadfin_school.jpg