6. Solution to Chemistry Problem

10. Analysis of a solution of a mixture of thallium (III) and zinc (II) containing 204Tl was carried out by precipitation titration with a 0.1 M solution of 1-dithiocarboxy-3-methyl-5-phenylpyrazoline C11H10N2S2Na labeled with 35S. The analyzed solution, ammonium chloride, sodium tartrate and NaOH were introduced into a centrifuge tube to pH 13.0. Then the titrant solution was added from a burette in 0.25 ml portions. After separating the precipitate by centrifugation, 0.01 ml of the solution was collected, applied to a filter, dried and the activity was measured. After reaching the first equivalence point, the pH of the solution was brought to 7.0 and titration was continued*. Plot titration curves and calculate the mass of thallium and zinc (g) in the analyzed solution using the following data:
V(C11H10N2S2Na), ml 0.25 0.50 0.75 1.00 1.1 1.25 1.50 1.75 2.00 2.25 2.50
A, imp/min 1500 1000 550 125 150 350 750 100 100 450 800