Question

In a $3m$ long narrow tube, $HCl$ is allowed to diffuse in the tube from one end and ${PH}_3$ from the other end, if diffusion started at the same time predict at what point the white fumes of ${PH}_{4}Cl$ will form?

(Write your answer up to 3 decimal places)

Answer 1

Let $N{H}_3$ diffuse through = x cm

HCI diffuses through = y cm

According to Graham’s law of diffusion

$x/y=\sqrt{\frac{\text{Mol. wt HCl}}{{\text{Mol. wt of NH}}_3}}=\sqrt{36.5/17}=1.465$

x = 1.465 y …(1)

x + y = 300 cm …(2)

From these equations; y = 121.7 cm

and x = 178.3 cm or 1.783m