6. Solution to Chemistry Problem

9. 1.00 ml of the test solution, zinc salt containing 0.238 mg of the 65Zn isotope, and different volumes (from 0.20 to 1.60 ml) of 0.0287 N K4Fe(CN)6 (feq=1/3) were added to the beaker for radiometric titration. After adding each portion of the titrant and mixing, a sample of the filtrate was taken, the activity was measured, and the sample was returned to the beaker. The obtained results are presented in the table:
V(K4Fe(CN)6) 0.20 0.40 0.60 0.80 1.0 1.20 1.40 1.60
A, cpm for variant 1 950 820 680 570 420 280 150 0
A, cpm for variant 2 1030 910 800 680 550 440 330 200
A, cpm for variant 2 930 720 520 310 100 0 0 0
Plot a titration curve and calculate the zinc concentration in the solution (mg/ml), if the activity of the solution before the titration was 1150 cpm.
Solution for variant 1