50. Solving a chemistry problem

2. Determine the specific surface of the adsorbent by the results of determining the adsorption of the dye, methylene blue (molecular weight - 319 g / mol, assuming that the area of the dye molecule in the monomolecular surface layer is 0.9 nm2. The adsorbent sample is 0.3 g, the volume of the solution is 25 ml, the initial concentration of the dye is 2.5 mg/ml, the final concentration is 0.2 mg/ml.