Solving a chemistry problem 000 001

1. Determination of substance A in the analyzed solution was carried out by direct potentiometry. First, standard solutions with different precisely known concentrations of C(A) of the analyte were prepared, after which the standard solutions were introduced alternately into an electrochemical cell, including the corresponding ion-selective indicator electrode and a chlorine-silver reference electrode, and the EMF E of the circuit was measured for each standard solution. Then, under the same conditions, the EMF of the circuit with the analyzed solution was measured.
Using the data below, construct a calibration graph* in coordinates E – pA, where
рА = –logC(A), and determine the molar concentration of substance A in the analyzed solution
Substance A EMF E of the circuit, mV
Standard solutions with concentration C(A), mol/l Analyzed solution
0.00001 0.0001 0.001 0.01 0.1
Ca2 – –28 –3 –97 22 47 -16