55. Solving a chemistry problem

20. The content of iron and cobalt in the solution was determined by the method of high-frequency titration. To do this, the test solution was brought to the mark with water in a volumetric flask with a capacity of 50 ml. A 5.0 ml sample was transferred to a titration cell. The titrant was 0.009469 M Na2H2 EDTA solution. We received the following data:
V(EDTA), ml 1.0 2.0 3.0 4.0 5.0 6.0 6.5 7.0 7.5 8.0
Instrument readings 47.7 45.0 43.0 40.5 38.0 35.0 34.0 33.0 31.0 30.0

V(EDTA), ml 8.5 9.0 10.0 11.0 11.5 12.0 13.0 14.0 15.0
Instrument readings 30.0 30.0 30.0 30.0 30.2 31.0 31.8 32.4 33.6

Plot the titration curve and calculate the mass of iron and cobalt in the mixture.