Where do HBr and NH₃ gases meet when diffusing toward each other?

[akademiks]

Urgent Help Needed! (gases)

I need some urgent help with figuring out how to find the distance which 2 gases will meet in this question..

Given: Samples of HBr gas and NH_3 gas are placed at opposite ends of a 1.80 m tube.
Question: If the two gases are allowed to diffuse through the tube toward one another, at what distance from each end of the tube will the gases meet and form solid NH_4Br?

Thank you to anyone who can help me with this, or at least set me in the right path.


The distance must be in Cm as well..

 

[Astronuc]

One may assume that the gases are at the same temperature.

Apply kinetic theory of gases and determine the mean velocity which is a function of molecular mass.

If one gases travels distance d in time T, then the other must travel 1.8m-d in the same time.