1. Air Quality: Carbon Dioxide Deborah Carlisle and Steve Schneider

2. The Big Idea: Measuring Relative Amounts of CO 2 Bromothymol Blue (BTB) changes color when CO 2 is added.

3. When CO 2 is added the solution becomes acidic.

4. What are we observing when BTB changes color? In solution BTB can be in a “protonated” form or an “deprotonated” form. It is protonated in acidic solution. H 2 CO 3  H + + HCO 3 -  H + + CO 3 2- Yellow Blue

5. Where does CO 2 come from? What will our students say?

6. Breath contains Carbon Dioxide Molecules

7. Compare Controls

8. Making BTB Each Group make up Refer to Handout and Use Tap Water

11. Control50mL of CO 2

12. 10 mL CO250 mL CO2

13. Calibration Scale

14. The Experiment Question: Can we prove breath is about 5% CO2? Join your assigned group of 4 Create a calibration scale for BREATH Photograph Import photo and sample the colors in your calibration scale using the line tool Make a graph of color intensity vs. percent CO2

16. Calibration Scale % CO 2 Control1.25 %1.75%2.5% 50 mL breath w/exercise

17. Graph Data from image sampled with rectangle tool

20. Graph Use graph Excel or graph paper to make a graph of your results

21. Results