Studying Ozone and Air QualityStudying Ozone and Air Quality

Steve SchneiderSteve SchneiderDeborah CarlisleDeborah Carlisle

Measuring Ground-level OzoneVOC’s + NOX + sunlight O3

Motor vehicles are the single largest contributor to ground-level ozone.

Measuring Ground-level OzoneO3 levels above 120 ppb are considered unhealthy. They can be generated by some electrical equipment or from photochemical reactions with smog:

VOC’s + NOX + sunlight O3

Motor vehicles are the single largest contributor to ground-level ozone. In this project we are adapting the relatively easy-to-make Schoenbein papers for classroom use, and using ADI to analyze the color changes quantitatively.

0-50 51-100 101-150 151-200 201-300 301-500

Commercial Papers:Ecobadge, Ozone badge

Findings:Commercial cards had significant variability

and were expensive.

Researched making Schoenbein papersInexpensive and safe to make

Schoenbein PapersOzone was discovered by C.F. Schoenbein in 1839. He developed an ozone-sensitive test paper that was widely used historically, and more recently in classrooms. The standard protocol for using the papers calls for an 8-hour exposure to the air out of direct sunlight. Various studies have shown a dependence on humidity, and there are a variety of recommendations for moistening the strips prior to exposure.

Control low O3 high O3

exposure exposure

Despite the method's early limitations, starting in the mid-1800s, more than 300 stations recorded ozone exposures in countries such as Austria, Australia, Belgium, England, France, Germany, Russia, and the United States.

Learning Goals :Learning Goals :

Analyze different relative amounts of ozone found in various locations using test results.Understand that ozone is found near the earth’s surface (ground level) in the troposphere as well as the stratosphere.Understand that ozone test strips/Schoenbien paper detect ozone gas through a chemical reaction that is caused by ozone in the air.Use technology to more precisely analyze relative color changes obtained with ozone test strips.

Some Testing Ideas:Some Testing Ideas:

Test for ozone at different times of day and look for patterns. When are ozone concentrations the highest?Test for ozone in various locations and see what areas are the highest.Look at the effects of wind patterns on ozoneStudents research and brainstorm where ozone might be found and what equipment/machines produce ozone

Making Schoenbein Papers

Classroom Use Made Easier:Classroom Use Made Easier:

1. Test strips can be stored in a double 1. Test strips can be stored in a double plastic zip lock bag, until you are ready to plastic zip lock bag, until you are ready to

read your results.read your results.

2. To look at results simply dip your exposed 2. To look at results simply dip your exposed test strip in a beaker of water. You will see a test strip in a beaker of water. You will see a

visible color change.visible color change.

3. Compare the relative colors to the control. 3. Compare the relative colors to the control.

4. Use digital analysis to measure RGB 4. Use digital analysis to measure RGB values and compare between test strips.values and compare between test strips.

Testing Ozone LevelsGroups of 4Select a test site

Things to ConsiderAvoid direct sunlightFree air circulation around your strip

Run a control with your groupLabel an index card with date/time/location

Outdoor exposure

Carrying Out the Experiment: Discuss experimental design in your groups

to come up with a plan for testingRun tests (place test strips and control)Collect test strips and place in zip-lock

baggiesReturn to lab and expose strips by dipping

in waterPhotograph test stripsData Analysis and share results

Data Analysis

How do Ozone Test StripsHow do Ozone Test StripsWork?Work?

Ozone is a strong oxidizer. It rapidly reacts with Ozone is a strong oxidizer. It rapidly reacts with the iodide ion, Ithe iodide ion, I-- in the KI salt applied to the filter in the KI salt applied to the filter paper. paper.

KI + HKI + H22O + OO + O33 I I22 + O + O22 + K + K++

II22 + I + I-- + starch + starch I I33-- + starch + starch

Last step : I3- (linear)+ starch (helix)

(Turns Blue)

Combination of I3- and helix

causes light reflection to be in the blue/violet range of visible spectrum

Schoenbein Papers

Cntrl 80 100 120 140+

Comparing Test Strips

Calibration of Test Strips

National Science Education Standards

Science as Inquiry: Grades 5-8 and 9-12

Ability to perform scientific inquiry, understanding about scientific inquiry

Science and Technology: Grades 5-8 and 9-12

Understanding about science and technology

Science in Personal & Social Perspectives: Grades 9-12

Environmental quality, changes in environments