Chemistry · Matter · Diffusion

Diffusion of NH₃ and HCl gases

Concentrated ammonia and concentrated hydrochloric acid are placed at opposite ends of a glass tube on cotton-wool plugs. Both gases diffuse along the tube. Where they meet, a white smoke of ammonium chloride forms — and the position of this ring tells you the relative speed of the two gases.

elapsed: 0.0 min

from NH₃ end

0.0 cm

from HCl end

0.0 cm

ratio

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Exam-style questions

1. The white ring forms CLOSER to the HCl end. Why?

2. What is the white solid that forms in the ring?

3. Graham's law predicts the ratio of rates. Using rate ∝ 1/√Mr, the ratio NH₃ : HCl is:

4. Why is concentrated ammonia and concentrated HCl used?