2. Solving a chemistry problem

5. Two volumetric flasks with a capacity of 100.0 ml were placed in 20 ml of waste water. 10.00 ml of a standard solution of CuSO4 (T(Cu=0.0010000) was added to one flask. Solutions of ammonia, rubeanic acid were added to both flasks and diluted with water to the mark. When photometry of the solutions was obtained, optical densities Ah = 0.280 and Ah st = 0.420 • Determine the concentration (g/l) of copper in the waste water.