The Specific Heat of Butoxyethanol/Water Critical Mixtures

Abstract

Results of measurements of the specific heat capacity of n‐butoxyethanol/water and iso‐butoxyethanol/water of critical composition as function of temperature are reported. Both systems have in common that in the vicinity of the critical temperature aggregates of butoxyethanol molecules and concentration fluctuations with unusual long range correlations (critical amplitude ξ0+ ≈︁ 0.4 nm) coexist. The analysis of the data shows that both systems belong to the same universality class as “simple” binary mixtures. The value of the critical amplitude ratio of specific heat capacity (A/A+) and the value of the critical exponent α are consistent with the predictions of the Landau‐Ginzburg‐Wilson model (d = 3, n = 1). The same is true for the value of the amplitude ratio RA,ξ+ calculated from the specific values of the critical amplitudes ξ0+ and A+.

Monomer Exchange and Concentration Fluctuations of Micelles. Broad-Band Ultrasonic Spectrometry of the System Triethylene Glycol Monohexyl Ether/Water

“…Because there do not seem to exist experimental data for the critical part à in the specific heat, we used the relation to calculate à from known ξ 0 and ρ cr data. Relation 37 follows from the two-scale-factor universality concept 77 that has been verified by results for several binary mixtures. ,,, Taking B̃ = 4185 J·kg -1 K -1 , which is the heat capacity of liquid water at room temperature, with à = 57.6 J·kg -1 K -1 (eq 37), according to eq 33 g = 0.81 follows from  BF . The value obtained for the coupling constant is quite reasonable, particularly because similar values have been found for other binary mixtures. , The verification by independent methods of the g -value for the C 6 E 3 /H 2 O system, however, is still necessary.…”

Monomer Exchange and Concentration Fluctuations in Poly(ethylene glycol) Monoalkyl Ether/Water Mixtures. Dependence upon Nonionic Surfactant Composition

“…In eq 27 à and B̃ are the critical contribution and the background part, respectively, of the specific heat c p at constant pressure. Since there are no c p data available, we utilized the relation that follows from the two-scale-factor conception , to calculate à values from the known ξ 0 and α data and from the density ρ cr at the critical point. We used the c p value for water (4185 J kg -1 K -1 ) for the background part B̃ of the (water-rich) mixtures.…”