Gas A is 16 times denser than gas B. 100 cm3 of diffuses in 20 seconds. Calculate the volume of B that will diffuse in 30 seconds?

For A: Rate(A) = (100 cm³) / (20 s) = 5 cm³/s, Density(A) = 16 × Density(B)
For B: Rate(B) = (V cm³) / (30 s) = V/30 cm³/s, Density(B) = Density(B)

By Graham’s law of diffusion : Rate(A) / Rate(B) = √{Density(B) / Density(A)}
(5 cm³/s) / [(V/30) cm³/s] = √{Density(B) / [16 × Density(B)]}
5 × (30/V) = 1/4
150/V = 1/4
V = 150 × 4
V = 600

Volume of B that will diffuse in 30 seconds = 600 cm³