When two cotton plugs, one moistened with ammonia and the other with hydrochloric acid, are…

When two cotton plugs, one moistened with ammonia and the
other with hydrochloric acid, are simultaneously inserted into opposite ends of
a glass tube that is 87.0 cm long, a white ring of NH4Cl forms where gaseous
NH3 and gaseous HCl first come into contact. NH3 (g) + HCl(g) _ NH4Cl(s) At
approximately what distance from the ammonia moistened plug does this occur?
(Hint: Calculate the rates of diffusion for both NH3 and HCl, and find out how
much faster NH3 diffuses than HCl.)