39. Solving a chemistry problem

7. Potentiometric titration of an aliquot (V ml) of a solution containing a mixture of Na2CO3, NaOH with HCl titrant with a concentration of 0.1000n gave the following data:

VT, ml 13.5 14.0 14.5 15.0 15.5 16.0 19.0 20.0 20.5 21.0 21.5
pH 9.4 8.9 8.6 7.9 7.0 6.7 5.8 5.2 3.9 3.0 2.7
VT is the volume of titrant, ml.
Using the differential titration curve, determine the content of the components in the mixture (in g/l) at the V values given in the table below.
option number 7
V, ml 35