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Air Pollution Revised Lab

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					Group members:                        Class: _________________ Period:____________

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Red Lab: Humans in the Biosphere

Investigating Air Pollution

Problem: How can air pollution be detected?

Introduction:

      Although life on Earth depends on air and water, we are endangering these
important resources by polluting them with harmful substances. The air we breathe
contains the oxygen our cells need, but it also contains many other chemicals that
can damage our bodies. Our atmosphere is polluted with smog, acid rain, carbon
dioxide, and a variety of other chemicals that create problems for all organisms
dependent on the atmosphere. In this investigation, you will conduct tests to
determine the types of pollutants present in samples of air taken from the area in
which you live.

                    Materials                      checked           returned/date
                                                   out/date
          1.   4 microscope slides
          2.   Petroleum Jelly
          3.   Tongue depressors
          4.   4 petri dishes
          5.   Glass-marking pencil
          6.   Microscope
Procedures: Write your initials on the line after each completed step.

1. Work in groups of two or four students. Obtain four glass slides, petroleum jelly,
four tongue depressors, and four petri dishes. Make four particle traps by using a
tongue depressor to smear the center of four glass slides with petroleum jelly. Place
each particle trap in the bottom half of a petri dish. Cover each petri dish
immediately. CAUTION: Wear your safety goggles and laboratory apron. Handle all
glassware carefully. __________

2. Select one location on the school grounds for your particle traps. After obtaining
your teacher’s approval, place the four petri dishes containing the particle traps in the
selected location. Make sure that the petri dishes are side by side. __________

3. Remove the lids of the petri dishes and expose the traps to the air for 20 minutes.
__________

4. At the end of the exposure time, replace the lids. Use the glass- marking pencil to
record the test location on the lid of each petri dish. Return to your classroom.
__________

5. Carefully remove the particle trap from the first petri dish and place it on the
stage of a microscope. Use the low-power objective to examine the slide. Count the
number of trapped particles and record this number in Data Table 1. CAUTION: Do
not touch or taste the particles you collect. Wear plastic gloves. Always handle the
microscope with extreme care, and do not use it around water or with wet hands.
Never use direct sunlight as the light source for the microscope. __________

6. Repeat step 5 for each of the remaining particle traps. __________

7. Calculate the average number of particles trapped at your selected location. Record
this average in Data Table 1. To find the average number, add the number of particles
counted on each trap and divide by 4. __________
 Laboratory Planning Format



Problem/Purpose

*Why are you doing the How can air pollution be detected?
experiment?

*What question are you
trying to answer?

Hypothesis:

How will the amount of
pollution present in
different samples of air
compare to the amount
of pollutants present in a
control sample of air?

Prepare an if/then
statement.

Independent Variables        Dependent Variables   Controlled   Control
                                                   Variables    Group
Describe your plan.

You will investigate the
amount of pollutants
present in air samples
from areas in which you
live. What will you need
to control?
Data Table/ Collection        Example of a data table

Prepare 2 data tables.        Data Table 1: Particle trap locations and number of
You will need a data table particles
for the following:
                               Particle Trap Location   Number of Particles
1. The location of each
particle trap and the
number of particles
trapped for each location



2. The average number
of particles trap using all
particle trap locations

Graph:

Use the results from
data table 1 to make a
graph. Plot the location
on the x-axis and the
number of particles on
the y-axis. Include the
average number of
particles for all traps in
this graph.

Use a computer to graph
your data using excel.
Analysis and Conclusion      To Be Completed AFTER Data Collection!

How did you measure air
pollution in this
investigation? What are
some weaknesses in the
way you measured air
pollution?

Were there any particle
traps in which you did not
see any particles? Can you
infer that air in such a
location is free of
pollutants?

In which location was the
greatest average number
of particles trapped?
What factors do you think
increased the average
number of particles
trapped in this location?

In what types of weather
you would expect air
pollution to be the worst?
Explain the basis of your
prediction.

				
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posted:8/23/2012
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