|MadSci Network: Environment & Ecology|
I do not know of a substance that will measure CO2 depletion: there will still be some CO2 there, if I understand your project correctly. There are a couple of ways to measure the gas concentration. Neither of them are cheap. What I would recommend is calling a local industrial hygiene consulting company in your area. They can help and possibly even donate time/equipment! You can find one by going to the web site: www.aiha.org and looking at the consultants listing. The two methods are as follows: (1) drawing air into a sampling tube. This has an accuracy of +/- 20%. These sampling tubes are made by the Draeger Company or the Sensodyne Company. (2) Using a direct reading instrument that measures CO2 and other gasses. These instruments can be rented from a company called HAZCO (1-800-332- 0435). They may even be able to help with the cost, since this is a school project. Good Luck!
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