Gas Adsorption and Surface Areas

5 Gas adsorption and surface areas (Characterisation of powder surfaces, Eds. G.D. Parfitt and K.S.W. Sing, Academic Press, London, 1976). 

The most common method for the determination of surface areas of powders is by the adsorption of an inert gas e.g. nitrogen or krypton. Adsorption is carried out in a high vacuum system and at low temperature. The BET isotherm, which is based on multilayer physical adsorption, can be expressed in the form  

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