Explain : Molar volume of gas.

1.	Explain : Molar volume of gas.
Answer» i. It is more convenient to measure the volume rather than mass of the gas. ii. It is found from Avogadro law that one mole of any gas occupies a volume of 22.4 dm³ at standard temperature (0°C) and pressure (1 atm) (STP). iii. The volume of 22.4 dm³ at STP is known as molar volume of a gas. iv. The relationship between number of moles and molar volume can be expressed as follows : Number of moles of a gas (n) = \(\frac{Volume\,of\,the\,gas\,at\,STP}{Molar\,volume\,of\,the\,gas}\) = \(\frac{Volume\,of\,the\,gas\,at\,STP}{22.4\,dm^3\,mol^{-1}}\) [Note : IUPAC has recently changed the standard pressure to 1 bar. Under these new STP conditions the molar volume of a gas is 22.71 L mol^-1]

Answer»

i. It is more convenient to measure the volume rather than mass of the gas.

ii. It is found from Avogadro law that one mole of any gas occupies a volume of 22.4 dm³ at standard temperature (0°C) and pressure (1 atm) (STP).

iii. The volume of 22.4 dm³ at STP is known as molar volume of a gas.

iv. The relationship between number of moles and molar volume can be expressed as follows :

Number of moles of a gas (n) = \(\frac{Volume\,of\,the\,gas\,at\,STP}{Molar\,volume\,of\,the\,gas}\)

= \(\frac{Volume\,of\,the\,gas\,at\,STP}{22.4\,dm^3\,mol^{-1}}\)

[Note : IUPAC has recently changed the standard pressure to 1 bar. Under these new STP conditions the molar volume of a gas is 22.71 L mol^-1]

Discussion