DougTheMapper - 17-1-2012 at 16:08
I was doing some research on SCUBA diving with the intent to construct some sort of apparatus to allow myself 10-15 minutes underwater at a maximum
depth of 10m, and I ran into an interesting chemistry-related dilemma in the process of determining my air budget.
If you have 1L of air at the surface, ~10m down (at 1 atm greater) you have .5L air. I have two theories and I cannot seem to find an explanation:
The first says that the person uses twice the air at 2atm since they inhale/exhale the same volume but at twice the pressure.
The second theory says that the air at 2atm weighs twice as much per volume and therefore contains twice the weight in oxygen. Thus, the person would
only really need to breathe half the volume to maintain their blood oxygen.
It basically boils down to whether the air mass or volume has to remain constant.
Can anyone shed some light on this? I've been doing research like crazy and I have even built an excel sheet to calculate my available air resources
and ballast requirements. I cant find any straight answer to this one!
Thanks,
-DTM
Neil - 17-1-2012 at 16:12
Look up "rebreather". Your O2 use remains the same.
neptunium - 17-1-2012 at 17:47
intuitively (spelling??) i would think the quantity of matter should remain the same ...but when we are dealing with breathing creatures...?
its an interesting question ! i would've seek out PV=NRT first but this doesnt include living animals!
DougTheMapper - 17-1-2012 at 22:14
Another thing I had not taken into consideration is the volume of the empty container. Pretend you stuff 2L of air into a 1L vessel, bringing it to
2atm.
You can only get 1L back out of it without a vacuum pump if the environment is at 1atm.
If the environment changes to 2atm, your tank appears empty right from the start!
ldanielrosa - 22-1-2012 at 18:05
Your oxygen use is proportional to your exertion. Your breathing is regulated by carbon dioxide in the lungs. It doesn't matter how much more usable
O2 you have available, when the lungs become acidic you exhale and inhale.