The spontaneous intermixing of molecules of different gases, due to collision, at a given temperature and pressure is called gaseous diffusion. When different gases are mixed together, they wish to have the same pressure everywhere. Thus, their molecules move from area of higher concentration to an area of lower concentration until their pressure becomes the same everywhere.
Conc. HCl solution, Conc. NH3, Solution.
Glass tube, ring stand, clamp, clamp holder, cotton balls, forceps, dropper, rubber stoppers, safety goggles.
- Take 100 cm. A long glass tube opened at both ends.
- Plug a cotton piece, soaked in NH, solution at one end and a cotton place, soaked in HCl solution at other ends.
- The vapors of both these gases escape into the glass tube simultaneously.
- The vapors of both NH3, & HCl are invisible. But when they meet with each other. They produce white fumes of NH4Cl.
- The NH3, gas diffuses from cotton plug (Higher concentration) into the tube (lower concentration). Similarly. HCl gas also diffuses from cotton plug (Higher concentration) into the tube (lower concentration).
This experiment demonstrates that gases spread by diffusion to areas of lower concentration.