Surface areas from the BET equation

The determination of surface areas from the BET theory is a straight forward application of equation (4.38). A plot of 1/[W(Pq/P) — 1] versus P/Pq, as shown in Fig. 4.1, will yield a straight line usually in the range 0.05 P/Po 0.35. 

Solving the preceding equations for W, the weight adsorbed in a monolayer, gives 

The total surface area can be calculated from equation (4.13), namely 

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