- #1
sgstudent
- 739
- 3
What does it mean by 21% oxygen and 79% nitrogen by volume?
Because won't the oxygen and nitrogen have the same volume which is the volume of the whole container?
nTRT/VT=nO2RT/VT+nN2RT/VT so why would we say oxygen is 21% by volume since the volume of the oxygen and nitrogen is the same which is the volume of the container?
I managed to find a link that kinda says that "by volume" represents the (w/v) ratio rather than the (v/v) ratio. Here it is at the bottom (http://forum.onlineconversion.com/showthread.php?t=11470). So if it was w/v the w would represent the weight of the gas in g while if the v represent the volume of the entire container?
But if the "by volume" is w/v how can I use that ratio to get my mole fraction? Because if I had 10000m3 at 1 atm and 298K with 21% oxygen and 79% nitrogen by volume (w/v), then the mass of oxygen is 2.1x109g and the mass of nitrogen would be 7.9x109g. So now if I used the formula mass/mr equals moles, I'd get a different total number if I used 10000000dm3/24dm3.
So I'm quite confused about what this "by volume" means and partial volume. Hope you guys can enlighten me here. Thanks :)
Because won't the oxygen and nitrogen have the same volume which is the volume of the whole container?
nTRT/VT=nO2RT/VT+nN2RT/VT so why would we say oxygen is 21% by volume since the volume of the oxygen and nitrogen is the same which is the volume of the container?
I managed to find a link that kinda says that "by volume" represents the (w/v) ratio rather than the (v/v) ratio. Here it is at the bottom (http://forum.onlineconversion.com/showthread.php?t=11470). So if it was w/v the w would represent the weight of the gas in g while if the v represent the volume of the entire container?
But if the "by volume" is w/v how can I use that ratio to get my mole fraction? Because if I had 10000m3 at 1 atm and 298K with 21% oxygen and 79% nitrogen by volume (w/v), then the mass of oxygen is 2.1x109g and the mass of nitrogen would be 7.9x109g. So now if I used the formula mass/mr equals moles, I'd get a different total number if I used 10000000dm3/24dm3.
So I'm quite confused about what this "by volume" means and partial volume. Hope you guys can enlighten me here. Thanks :)