33. Solving a chemistry problem

7.19. Calculate the electrokinetic potential from the experimental data of electrophoresis of silicon hydroxide sol in Cd(NO3)2 solutions:
С Cd(NO3)2, mmol/l 0 1 3.6 15.0
Electrophoretic mobility, U0*10-19, m2/(s*V) 25 19 11 6.5
relative permittivity of the medium 80.1, viscosity 1*10-3 Pa*s, the dispersed phase moves to the anode. Plot the ζ-potential as a function of Cd(NO3)2 concentration. Explain the obtained dependence.