Diffusion is the transport of microscopic particles such as atoms, molecules, and ions due to differences in concentrations. It plays an important role in numerous processes. For example, diffusion can bring reactants together in chemical reactions and, in some cases, can be the rate-limiting step in the process. CE 110 is equipped with two experimental units to investigate diffusion in liquids and gases. To investigate diffusion in liquids, a concentrated salt solution is used. The solution is contained in a U-shaped tube, the end of which has a disc with several vertical capillaries. The U-tube is immersed in a tank containing demineralized water so that the disk with the capillaries is located below the water surface. The concentration gradient between the water and the solution causes the salt ions to move out of the U-tube through the capillaries to the demineralized water. Capillaries ensure that ions move in one dimension. An agitator in the tank prevents the salt concentration from increasing near the disc, thus avoiding concentration differences in the tank.

Code: CE 110