Determine the molecular formula of the oxide of phosphorous when it is in its gaseous state.
We know that PV=nRT
P=1 atm (760 mmHG is 1 atm)
V=0.0995 L (99.5 cm3=99,5ml=0.0995 L)
We need n (moles)
So n= PV/RT ...
The solution involves calculations of moles using the gas law, and a subsequent calculation of molar mass.