Analytical Chemistry

(8) A 50 cm^3 aliquot of a lead nitrate solution in 0.1 M KNO 3 was titrated amperometrically with 0.05

M potassium dichromate. The burette readings and corresponding values of cell current were as
follows:

Volume of K 2 Cr 2 O 7 /cm^3 Cell current/μA

0 84.0

1.00 66.2

2.00 48.3

3.00 31.7

4.00 15.3

5.30 12.0

5.50 21.9

6.00 43.9

6.50 67.0

Plot the titration curve and determine the end-point volume and concentration of the original lead nitrate
solution.