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 predict at what point the white fumes of ${PH}_{4}Cl$ will form?

Answer 1

Let us say at 0, i.e., at x m from A $P{H}_{4}Cl$ is formed.

$\frac{{\gamma }_{HCl}}{{\gamma }_{{PH}_3}}=\frac{\sqrt{M_{{PH}_3}}}{\sqrt{M_{HCl}}}⟹\frac{\frac{x}{t}}{\frac{3-x}{t}}=\frac{\sqrt{18}}{\sqrt{36.5}}⟹\frac{x^2}{9-6x+x^2}=\frac{18}{36.5}⟹18.5x^2+108x-162=0⟹x\approx 1.24m$ (negative value is ignored)