24. Solving a chemistry problem

20. Plot a graph of the dependence of the electrokinetic potential of the surface of the dispersed phase (electroconundum, a-Al2O3) on the concentration of electrolyte SEL (sodium hexametaphosphate) according to experimental data of electroosmosis:
Sal, % 0.02 0.05 0.10 0.20
v *103, ml/s 1.85 1.25 2.01 1.28
I*103, A 1.70 1.70 2.15 3.30
κ_v*102, cm*m-1 2.40 3.91 6.10 10.20
κ_s*102, cm*m-1 7.76 6.42 0.49 0.20
The relative dielectric constant of the solutions is 80.1, viscosity is 1*10-3 Pa*s. Determine the sign of the membrane surface charge if solutions move to the cathode under the influence of current.