Investigation Of The Critical Crossover Phenomena In Ternary Solutions Of Water +3-Methylpyridine+ Sodium Bromide

The critical phenomena of water + 3-methylpyridine + sodium bromide have been studied by measuring refractive indexes in two coexisting phases.The refractive index measurements have been carried out at 0.24, 0.17 and 0.08 mass fraction of sodium bromide. The analyses of the refractive index data in terms ofthe Sengers's crossover theory lead to obtaining the effective critical exponent β_eff Ithas been found that the effective critical exponent decreases as the distance from the critical point increases, but it exhibits the crossover from Ising to mean-field critical behavior after the regular term is subtracted. The results show that the values of theeffective critical exponent β_eff for the systems are close to the 0.365 at the higherconcentration of sodium bromide which is in well agreement with the Fisher renormalization value.