Adiabatic Coupling Constant g of the Binary Liquid Mixture Methanol–Cyclohexane

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Saja Ghazi Omar

The dynamic shear viscosity of the binary liquid mixture methanol - cyclohexane for different temperatures and concentrations is measured using digital viscometer with UL adapter. Shear viscosity anomaly is clearly observed near the critical temperature Tc = 45.2 ℃ and the critical concentration Xc = 30% by weight of methanol. The specific heat at constant pressure of the critical mixture methanol – cyclohexane was calculated using two scale factor universality. The dynamic scaling theory of Ferrell and Bhattacharjee is applied to the data of the ultrasonic absorption coefficients αc at different frequencies. The linear relation of  αc/ ƒ2  versus ƒ(-1.06)  was obtained. The adiabatic coupling constant g, isobaric thermal expansion coefficient αp and diffusion coefficient D were calculated. The experimental values of α(Xc ,T) / α(Xc ,Tc)   were plotted as a function of the reduced frequency ω* and it showed a good agreement with the theoretical scaling functionF(ω*)presented by Ferrell and Bhattacharjee.

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