German version
| Supermarket product: | red wine |
| Materials and chemicals: | round filter | charcoal |
Apparatus and glasswares:
| 2 wine glasses
| beaker 250 mL
| glass funnel d = 10 cm
| filter stand
| glass stirring rod
| |
Experimental procedure:
5 g of charcoal are added to 90 mL of red wine while stirring. The suspension is filtered through a round filter paper.
| Result:
A colorless filtrate is produced. | 
 Video clip
(Download RealPlayer .rm-Datei) |
Discussion and background:
Adsorption means the accumulation of gaseous or dissolved substances at the surface of a solid substrate due to physical or chemical forces. The physical adsorption (physisorption) in the available case is the most common form of adsorption. The molecules are attracted by van der Waals forces (dispersion forces and dipole-dipole interactions) between adsorbate molecules and the atoms which compose the adsorbent. The forces are small, and short-range. Dispersion forces are based upon the non-constant distribution of the charge in molecules without dipoles. The constant fluctuation of the electrons in the molecule causes temporary dipoles which induce dipole moments also in neighbouring molecules. On the other hand, the permanent, in-built dipoles will cause the molecules to attract each other rather more than they otherwise would if they had to rely only on dispersion forces.
Electronmicroscopical Pictures of Charcoal (Lurgi GmbH)
