11. Solving a chemistry problem

133. According to the results of high-frequency titration of 10 cm3 tenfold diluted sulfate black liquor with 0.1 M HCl solution:
V(HCl) 0 1.0 2.5 4.2 5.2 7.0 9.0 10.0 10.5 11.0 12.0 12.5
I, mA 18 38 56 80 82 70 8 50 38 30 20 12
Plot the titration curve and calculate the concentration of effective and total alkali (g/dm3 in terms of Na2O), provided that the first inflection of the titration curve corresponds to the effective alkali concentration, and the second to the complete completion of the alkali titration.