Surface Chemistry

Adsorption: The phenomenon in which the molecules of a substance are attracted and adhered to the surface of a solid or liquid. Adsorption is a surface phenomenon. Adsorption is a exothermic reaction. Released heat is called Heat of adsorption.

In the exterior of solid unbalanced forces and interior of the solid balanced forces are present. Due to unbalanced forces on the surface it attracts molecules of gas or liquid. The attraction and accumulation of gas or liquid molecules on to the surface of solid is called Adsorption.

If gas or liquid molecules are uniformly distributed through out the interior is called absorption. Thus, adsorption is surface phenomenon and absorption is bulk phenomenon. If the adsorbed gas or liquid leaves the surface it is called as dissipation.

Catalysis

According to Berzilius, catalysts increases the rate of reaction by loosening the bonds in reactants. Catalyst is the substance which alters the speed of reaction without undergoing any chemical change.

Homogeneous catalysis: Catalyst and reactants are in some physical state.

Heterogeneous catalysis: If the reactants and catalyst are in different physical states, it is called Heterogeneous catalysis. Usually reactants may be gases or liquids and catalysts are solids.

Tyndall Effect

The phenomenon of the scattering of light by the colloidal particles is called Tyndall effect.

Example: Blue appearance of sky and sea water.