Science Buddies: "Ask an Expert"

Hello, PleasePleasePlease help me. Ohkay, its about the gas collection thing. How exactly WILL the gas be collected? Do i just stick the tube up the gas collection cylinder?? Will the water just be...pushed out of the tube and thats how I will know how much Carbon Dioxide is made?? PLEASE REPLY SOON. Thank youuu

I'm not sure I understand your question. If you can provide more information (e.g. purpose, procedures, etc), I will be able to help you better.

I'm unclear about your first two questions, but I assume that you are doing a project in which you measure the amount of CO2 given off be respiring anaerobic organisms. Is this correct? If you are doing such a project, the simple answer to your third question is yes; the volume of water displaced by the incoming gas can be thought of as the amount of CO2 produced by the experiment.

Ohkay, in the procedure, [[because i will be measuring how much CO2 will be produced from the yeast with or without aeration]]. you have 2 bottles, one where you have yeast with air, and yeast without air. You cap the bottle with a cap that fits it and put a hole in the cap that is big enought to put aquarium tubing inside of it. It says you need to stick the aquarium tubing out just about 2 cm and put it in the gas collecting system [[an inverted graduated cylinder that is placed and filled with water]]. But what i dont' understand, is how can i make the aquarium plastic tubing go inside of the gas collecting system?? And will the graduated Cylinder just push the water out and thats how i can see how much CO2 is created? im sorry..if this makes no sense..i can't really explain it!

No, your making perfect sense. I would suggest that you leave a lot more than two inches of tubing sticking out of the end of the bottle, probably about 2 feet. You can get a large container, like a large beaker and fill it with water. Then invert a graduated cylinder in the beaker. Run the aquarium tubing into the graduated cylinder, just like you were putting a hose into the cylinder. The tubing should go over the edge of the beaker and under the edge of the graduated cylinder. The gases produced during respiration (CO2) will displace a volume of water that is proportional to the amount of CO2 produced, so yes, you can think of the gas as pushing the water out of the graduated cylinder; the amount of water that is pushed out is proportional to the amount of CO2 produced (i.e. is more water is pushed out, then more CO2 was produced).

Oh Ohkay! I get it now! Thank you so much. That answers all of my questions. Thank you once again.