Chapter 8, Problem 89E

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 1111g of ${\text{NH}}_4\text{Cl}$ forms where gaseous ${\text{NH}}_3$ and gaseous HC1 first come into contact. ${\text{NH}}_3\left(g\right)+\text{HCl}\left(g\right)\to {\text{NH}}_4\text{Cl}\left(s\right)$ At approximately what distance from the ammonia moistened plug does this occur? (Hint: Calculate the rates of diffusion for both ${\text{NH}}_3$ and HCI, and find out how much faster ${\text{NH}}_3$ diffuses than HCI.)