6. 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 6
Surfactant Heptanoic acid CH3(CH2)5COOH
Concentration C*103, kmol/m3 0.000 0.080 0.160 0.250 0.400 0.500 0.630 1.000
Surface tension b*103, J/m2 72.75 60.00 50.50 40.50 35.00 32.00 30.00 28.00

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