Q 2.17: One mole of an ideal gas at standard temperature and pressure occupies 22.4 L (molar volume). What is the ratio of molar volume to the atomic volume of a mole of hydrogen? (Take the size of hydrogen molecule to be about 1 Å). Why is this ratio so large?
Radius of hydrogen atom = 0.5 = 0.5 x 10-10 m (Size here refers to Diameter!)
Volume occupied by the hydrogen atom=
1 mole of hydrogen contains 6.023 x 1023 hydrogen atoms.
Volume of 1 mole of hydrogen atom = 6.023 x 1023 x 0.524 x 10-30
= 3.16 x 10-7 m3
The molar volume is times greater than the atomic volume.
Hence, intermolecular separation in gas is much larger than the size of a molecule.