Posted by Neha ghatia on .
The density of air is 1.25 gram per liter determine the volume percentage of oxygen in the air at 1 atmospheric pressure and 27 degree celcius temprature? Assume air is a mixture of nitrogen and oxygen.

chemistry 
bobpursley,
Nuts to this. If the volume is one liter, you have one liter of Nitrogen, and one liter of oxygen. Gases spread to fill the volume.
If you want the mass percentage, that is easy.
Assume a volume V.
MassV= 1.25V grams.
but massV=molemassAir*molesAir.
now, molesair = PV/RT
molemassAir=massV*RT/PV=1.25RT/P
so calculate that.
Now, molemassAir=32X+28(1x)
and you can solve for X (percent of O2 by mass).