Why do we define percentage by volume for an ideal gas in a closed container in spite of that we know the ideal gas will occupy the volume of the whole container?
I have seen many people who prove that % by volume is equal to the percentage by mol for an ideal gas (at constant temperature and pressure conditions). They follow the following procedure...
PV = nRT
V = nRT/P
(let RT/P = K as a constant as pressure and temperature are constants)
as volume is directly proportional to the number of moles and hence % by volume is equal to the percentage by mole...
But the doubt is here, when we write PV=nRT for a gas in a closed container then we write volume as the volume of the container then where do we define % volume for gas?