Diffusion and Osmosis

Brownian molecular motion

Principle

Molecules in liquids are relatively free to move. They can transfer their energy to neighbouring molecules, causing them to oscillate. This allows the motion of the molecules to be observed indirectly simply using a microscope.

Osmosis: a "chemical garden"

Principle

One impressive example of osmotic processes is the "chemical garden". Metal salts dropped into a solution of sodium silicate react with the silicate immediately, forming non-soluble silicate shells, which stop the reaction from proceeding further. However the shells ...

Particle motion (diffusion, thermal agitation)

Osmosis - dependence of the osmotic pressure on the concen-tration

Diffusion in gases: the diffusion coefficient of bromine in air

Principle

Diffusion arises from the flow of matter down a concentration gradient. In the evaporation method, a stationary concentration gradient is achieved in which the concentration decreases linearly with distance. Under these conditions the diffusion coeffi ...

Determination of diffusion potentials

Principle

An electrochemical potential establishes itself at the interface between two solutions of different ion concentrations. The magnitude of this is determined by the concentration ratio and the transference numbers of ...