Biogas experiment- unexpected results

[miawest]

My daughter is doing the science experiment on capturing biofuel from biomass (cow manure and rotting food). However, 2 out of 3 her bottles have not only NOT inflated the balloons, but the balloons are starting to get sucked into the bottles. We are trying to figure the reason why this is happening. Help!

[sunmoonstars]

I think Thats related to pressure difference caused by temperature difference from the decomposition. HVe a read here, and let me know if this is what seems like happened.
http://en.allexperts.com/q/Chemistry-in ... ethane.htm

Or, there could be a crack or hole in one of the bottles, caps, or balloons somewhere. Did you inspect them well?

Tonya

[amyc]

Tonya, the link doesn't work.

[deleted-284605]

I'm guessing this is the webpage to which Tonya was linking.

[miawest]

My daughter spoke with a biochemistry professor who explained the processes of aerobic and anaerobic bacteria. Without going into too much detail, the oxygen was used up, so the volume of air decreased creating a void, if you will. Therefore the balloons were getting sucked in to compensate for the empty space. That's the way I understood it, but I could have totally misunderstood their conversation!

Thanks for the help!

[sunmoonstars]

Miawest - that makes sense. Thanks for passing the info to me! I hope you enjoyed the project & learning experience overall.

Tonya