6. Solution to Chemistry Problem

9. Copper was extracted from a sample of soil weighing m g by shaking with 50.00 ml of a dilute HCl solution; copper was extracted from 25.0 ml of the filtrate with 10.0 ml of a solution of sodium diethyldithiocarbamate in carbon tetrachloride and the optical density of the organic phase was measured. Similarly, copper was extracted from four standard solutions prepared by mixing Vst ml of a working solution of CuSO4 containing 10.0 μg in 1.0 ml (25.0 –Vst) ml of HCl solution, and the optical densities of the organic phases Аст were measured again:
Vst, ml 0.2 0.5 1.0 2.0
Аст 0.025 0.065 0.120 0.245
Determine the concentration of copper in the soil (mg/kg), if the values ​​of Ах were found for the studied soil samples:
Option 1 2 3
m, g 10.06 9.85 8.95
Ах 0.072 0.080 0.125
Solution for option 1