Question

Estimate the fraction of molecular volume to the actual volume occupied by oxygen gas at STP. Take the diameter of an oxygen molecule to be 3Å.

Answer 1

Diameter of an oxygen molecule, d = 3Å

Radius, r = d/2 = 3/2 = 1.5  Å = 1.5 × 10^–8 cm

Actual volume occupied by 1 mole of oxygen gas at STP = 22400 cm³ 

Molecular volume of oxygen gas, V = (4/3)πr³. N

Where, N is Avogadro’s number = 6.023 × 10²³ molecules/mole

Ratio of the molecular volume to the actual volume of oxygen = 8.51/22400

= 3.8 x 10^-4