19. Solving a chemistry problem

183. From the analyzed solution with a volume of 100 ml containing a colored ammonia complex of copper (II), a sample was taken and its optical density Ax = 0.500 at λ = 610 nm was measured in a cuvette with ℓ = 2 cm. Five standard solutions were prepared with an accurately known concentration of copper (II), measured their optical density A and obtained the following results:

С (Cu2 ), mg/ml 0.05 0.10 0.15 0.20 0.25
A 0.158 0.316 0.474 0.632 0.790
Build a calibration graph in the coordinates A - C (Cu2 ), mg / ml according to the results. Determine the concentration C (Cu2) and the mass m(Cu2) of copper (II) in the analyzed solution.