8. Based on the data on the dependence of the surface tension of aqueous solutions of surface-active substances (surfactants) on concentration at a temperature of 293 K (Table 1), perform the following tasks:
• calculate, using the analytical method, the value of Gibbs adsorption Г;
• construct adsorption isotherm;
• plot the surface tension isotherm σ=f(C) and determine the magnitude of the surface activity;
• perform graphical differentiation of the surface tension isotherm and calculate the amount of adsorption;
Draw conclusions about the accuracy of the analytical and graphical methods for calculating the adsorption value G.
Option 8
Surfactant 1,3-Butanediol HOCH2CH2-CH(OH)CH3
Concentration C*103, kmol/m3 0.000 0.650 1.440 2.240 3.300 5.400 7.000 10.000
Surface tension b*103, J/m2 72.75 64.30 60.00 57.50 55.00 48.60 46.00

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