Question

A bottle of dry ammonia and a bottle of dry hydrogen chloride connected through a long tube are opened simultaneously at both ends, the white ammonium chloride ring first formed will be:

• A. at the centre of the tube.
• B. near the hydrogen chloride bottle.
• C. near the ammonia bottle.
• D. throughout the length of the tube.

Answer 1

Answer: (B)

near the hydrogen chloride bottle.

The rate of diffusion of a gas is Inversely proportional to the square root of its molecular weight.

Thus, rate of diffusion $r=\alpha \frac{1}{\sqrt{M}}$.

The molecular weight of HCl is higher than that of ammonia.

The rate of diffusion of ammonia is higher than the rate of diffusion of $HCl$.

Therefore, ammonia will travel more distance than $HCl$ at the same time interval and the two gas will first meet nearer to $HCl$ end.

So, the correct option is $B$