18. Solving a chemistry problem

217. The adsorption of dyes from solutions is often used to approximate the specific surface area of powders. Suppose, in portions of 100 cm3 of methylene blue solution with an initial concentration of 1.00 * 10-4 mol/l, different weights of bone charcoal are added and the remaining concentration in the solution is determined after reaching equilibrium. When making a sample of 1 g, the final concentration was 6.0*10-5 mol/l, and when making 2 g - 4.0*10-5 mol/l. It is known that the area of a methylene blue molecule in a monomolecular layer is 65 A2. Calculate the specific surface area of coal, assuming the Langmuir equation is correct.