47. Solving a chemistry problem

3. To prepare a standard solution of zirconium, a sample of ZrOCl2•8H2O weighing 0.3533 g was dissolved in 100 ml of HCl. In volumetric flasks with a capacity of 50.00 ml were placed 1.00; 1.20; 1.50; 1.70; 2.00 ml of the standard solution, gallocyanine MS (zirconine) was added and made up to the mark with water. Measured optical density relative to the first solution. Received Aotn for the second, third, fourth and fifth solutions, respectively: 0.100; 0.235; 0.330; 0.470. A portion of a zirconium alloy weighing 0.1242 g was dissolved in 100 ml of a mixture of acids. A 2.00 ml aliquot was taken into a 50 ml volumetric flask, zirconin was added and made up to the mark. Arel.x=0.380 was measured. Calculate the mass fraction of zirconium in the alloy.