Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA Surface area and pore size distribution are attributes used by adsorbent and catalyst manufacturers and users to ensure quality control and to determine when products are at the end of their useful lives. The surface area of a porous solid is directly related to its adsorption capacity or catalytic activity. The pore size distribution of an adsorbent or catalyst is controlled such that pores are large enough to easily admit molecules of interest, but small enough to provide a high surface area per mass. Surface area and pore size distribution can be measured by the technique of isothermal nitrogen adsorption/desorption. In this experiment, a nitrogen porosimeter will be used to measure the surface area and pore size distribution of a silica/alumina powder.