Experiment: To observe diffusion of gases:
Method:
Take two cotton plugs, one soaked in ammonium hydroxide (liquid) and another in hydrochloric acid (liquid). Place them simultaneously at the two ends A and B of a long glass tube. Close the two ends of the tube immediately.
After some time, a white ring of a solid substance is formed near the end B. the molecules of ammonium hydroxide and hydrochloric acid move in opposite directions and meet to react.
Finally ammonium chloride, a white solid is formed in the form of a ring. The formation of the ring near to the end B shows that the molecules of ammonium hydroxide have covered larger distances.
ADVERTISEMENTS:
This means that these molecules move faster than the molecules of hydrochloric acid. This is because the molecules of ammonium hydroxide are lighter.