Activation energy in physical adsorption Physical adsorption of molecules on surface requires activation energy, because bonds of the adsorbed molecules are broken.


Is this a valid statement? 

I have been under the assumption that physical adsorption does not involve any energy of activation as there is no chemical bond formation between the adsorbed molecules and the surface (and hence there is no necessity for bonds of adsorbed molecules to be broken).
The definition given above would more closely describe chemisorption. At large separation from the surface the interaction is zero. In physisorption the interaction becomes attractive and forms a potential well as the surface is approached. There is no activation energy needed to do this. At shorter separations than the potential minimum, the potential becomes repulsive. The minimum is usually at larger separation than the minimum for equivalent species exhibiting chemisorption. Species may physisorp before chemisorption occurs



Comment by porphyrin converted to answer