10. Solution to Chemistry Problem

9. The mass concentration of iron in the solution was determined by the spectrophotometric method, measuring the optical densities of solutions colored as a result of the reaction of the Fe3 ion with sulfosalicylic acid. To construct a calibration curve, the optical densities of solutions with increasing (specified) iron concentrations treated with sulfosalicylic acid were measured. The obtained data are presented in the table:

xi 0.010 0.020 0.030 0.040 0.050

yi 0.100 0.210 0.290 0.420 0.530

The optical densities of the comparison solution (control experiment for reagents, i.e. without adding iron, (background)) were 0.002; 0.000; 0.008; 0.006; 0.003. Plot a calibration graph for determining iron in water. Calculate the detection limit of iron.