I'm so lost, how do you collect a gas over water? what materials do you need? and how do you set it up?

Answer 1

Normally, you have a tray filled with water several inches deep at least. Then sink a suitable-sized bottle in the water, let it fill, invert with the bottle mouth still under the surface so it stays full of water. Now, you run the tube from your reaction or other gas-generating process up into the bottle so the gas is trapped there and displaces the water as it accumulates. Obviously this method is not suitable for gases highly soluble in water like ammonia or hydrogen chloride.

Answer 2

Wow...you just hit the mother load.... I work for a company that is known world wide for gas sampling. What you are looking for is called a "head space" sample. Two ways to collect this....one is with a detector tube that measures the exact gas that you are looking for. The tube is inserted into a pump device that looks like a bicycle pump & the sample is taken right over the water and an immediate reading is given by a color change. You do need to know the "target" gas for this application. Next is a sample that is drawn into a "tedlar" bag. This would be drawn w/ a pump that actaully draws the sample into the bag & then goes to a lab for analysis. You may try to contact a local university w/ a chemical/ hygiene program & they will usually help you.
I hope this helps!!!