Lesson Description:
This exercise is divided into three parts. in part one of the exercise, students use bromothymol blue (btb) to detect the presence of carbon dioxide in a test tube that contains the gas collected from the combination of vinegar and baking soda. students observe the color change as compared to an untreated control tube. in part two of the experiment, students use btb to detect the amount of co2 present in their breath, air from a bicycle pump, and car exhaust. they observe the color change to the btb and record their observations. in part three, they observe the amount of ammonia required to return the contents of each of the experimental tubes to their original color. they then answer a series of questions about the amount of co2 in each of the variables tested.

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Sustainability Topic:

• Other

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Standards Addressed:
-middle school
content standard b – transfer of energy
content standard d – structure of the earth system

-high school
content standard b – the interdependence of organisms
content standard d – energy in the earth system
content standard d – geochemical cycles
content standard f – environmental quality

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Materials Needed:
For each two-student team

-test tube rack
-six test tubes
-one hole stopper with tubing attached
-baking soda
-vinegar
-one-inch square of aluminum foil
-cotton balls
-bottle of btb working solution
-air pump (bicycle pump or sportsball pump will work)
-squirt bottle of dilute ammonia
-masking tape
-duct tape
-three balloons (different colors)
-markers
-balloon-size template (directions below)
-three straws
-pipette or eye dropper
-ten twist ties
-newspapers
-student instructions and data charts (in student guide)

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Notes:
For More Information Please Visit:http://www.ucar.edu/learn/1_4_2_17t.htm

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