33. Solving a chemistry problem

14. A sample of the metal 0.5000 g was dissolved and after the oxidation of the manganese contained in it to MnO4-, 100 ml of the solution were obtained. A 0.01 M KMnO4 solution was used as a standard. When compared in a colorimeter, the intensity of the optical densities of the standard and test solutions turned out to be equal at a layer thickness of 5 and 8.5 cm, respectively. Determine the mass fraction of manganese. Answer: 6.48