17. Solving a chemistry problem

188. Calculate the minimum mass fraction of zirconium (ω,%), which can be determined in trichlorosilane by the fluorimetric method, using the following data. From a sample of trichlorosilane with a volume of 7.50 ml (p = 1.344 g/cm3), 2.50 ml of the analyzed solution is obtained after appropriate treatment. Add 0.5 ml of an alcoholic solution of morin to the device with the analyzed solution, and after 15 min the fluorescence intensity of the zirconium complex with morin is measured. The minimum value of the analytical signal recorded by the fluorimeter is 5 c.u. The maximum value of the analytical signal recorded by the fluorimeter is 100 c.u. and corresponds to a zirconium concentration of 0.05 µg/ml. The analytical signal of the control experiment is 5 c.u.