RAYLEIGH AND BRILLOUIN-SCATTERING IN SEVERAL BINARY-SOLUTIONS - DERIVATION OF THERMODYNAMIC QUANTITIES OF MIXING

The Rayleigh and Brillouin scattering experiments have been carried ou t for the systems of benzene-primary alcohols CnH2n+1OH (n=1 to 5) and benzene-ethyl ether in order to make sure the applicability to the ar guments on the thermodynamic quantities based on the density and conce ntration fluctuations proposed by Bhatia and Thornton. The effect of t he difference in the molar volumes of the constituents is, in particul ar, emphasized for the obtained concentration-concentration fluctuatio n in the long wavelength limit, S-cc(O, c, T). A new method is also pr oposed to derive the Gibbs free energy of mixing Delta G, by using the data of S-cc(0, c, T). The obtained Delta G for benzene-ethyl ether i s nearly equal to RT(clnc+(1-c)ln(1-c)) and those for benzene-pentanol , butanol and propanol are, more or less, similar to those of typical binary fluids. While, Delta G's of benzene-methanol and ethanol in the ir magnitudes show phase separation tendencies, which are also seen in the shapes of S-cc(O, c, T)'s.