Coexistence curves of the binary mixture isobutyric acid–water with added ions (K+,Cl−)

Toumi, A.; Bouanz, M.; Gharbi, A.

doi:10.1016/s0009-2614(02)01107-7

Cited by 32 publications

(23 citation statements)

References 13 publications

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“…Phase transition at the critical point is classified as a continuous one and belongs to the universality class [3,1], as for example a critical point of gases. The critical mixing temperature (T c ) is very sensitive to many factors, for example, to impurities, 1,2 to pressure, 3,4 and to shear flows. 5,6 It would seem, therefore, that the critical temperature should be sensitive to the electric field too.…”

Section: ■ Introductionmentioning

confidence: 99%

Shift of the Critical Mixing Temperature in Strong Electric Fields. Theory and Experiment

et al. 2014

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We study the shift in the critical temperature T(c) in binary mixtures in strong electric fields. In experiments we measure the nonlinear dielectric effect (NDE) in a mixture of nitrobenze and n-octane and calculate Piekara's factor. We find that the critical anomaly of Piekara's factor is a function of an electric field strength. We propose to explain this observation as a result of a downward shift of T(c), and this allows us to calculate (∂T(c)/∂E(2)) = (-22 ± 10) × 10(-16) (K m(2))/V(2). In the theoretical part we amend Landau and Lifshitz's formula and show that the downward shift of Tc can be estimated from a simple mean-field theory taking into account the linear and quadratic terms in an expansion of the constitutive relation ε(x) between the electric constant ε and mixture composition x.

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Section: ■ Introductionmentioning

confidence: 99%

Shift of the Critical Mixing Temperature in Strong Electric Fields. Theory and Experiment

et al. 2014

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“…Visual observation of critical opalescence and the disappearance of the meniscus in our sample of 38.8 mass % isobutyric acid + water showed that the critical temperature was 26.10 °C. Since the addition of a solute, even in a small amount, ordinarily produces a noticeable shift in the critical temperature of a binary liquid mixture, − preliminary experiments were required to find appropriate values for the concentrations of acetone and potassium triiodide. These concentrations could not be so high as to shift the critical temperature outside the easy operating range of our water bath nor could they be so low as to cause the value of k obs to be immeasurably small.…”

Section: Experimental Methodsmentioning

confidence: 99%

Reaction Kinetics and Critical Phenomena: Iodination of Acetone in Isobutyric Acid + Water near the Consolute Point

Baird

2009

J. Phys. Chem. A

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The rate of iodination of acetone has been measured as a function of temperature in the binary solvent isobutyric acid (IBA) + water near the upper consolute point. The reaction mixture was prepared by the addition of acetone, iodine, and potassium iodide to IBA + water at its critical composition of 38.8 mass % IBA. The value of the critical temperature determined immediately after mixing was 25.43 degrees C. Aliquots were extracted from the mixture at regular intervals in order to follow the time course of the reaction. After dilution of the aliquot with water to quench the reaction, the concentration of triiodide ion was determined by the measurement of the optical density at a wavelength of 565 nm. These measurements showed that the kinetics were zeroth order. When at the end of 24 h the reaction had come to equilibrium, the critical temperature was determined again and found to be 24.83 degrees C. An Arrhenius plot of the temperature dependence of the observed rate constant, k(obs), was linear over the temperature range 27.00-38.00 degrees C, but between 25.43 and 27.00 degrees C, the values of k(obs) fell below the extrapolation of the Arrhenius line. This behavior is evidence in support of critical slowing down. Our experimental method and results are significant in three ways: (1) In contrast to in situ measurements of optical density, the determination of the optical density of diluted aliquots avoided any interference from critical opalescence. (2) The measured reaction rate exhibited critical slowing down. (3) The rate law was pseudo zeroth order both inside and outside the critical region, indicating that the reaction mechanism was unaffected by the presence of the critical point.

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“…The impurity effects on the critical behavior of binary liquid mixtures have been of an experimental continuing interest and of great fundamental practical importance and received a great deal of attention [1][2][3], since the importance of such investigations extends into both theoretical and practical fields. The influence of ionic impurities is known to significantly affect both the temperature and the concentration of the critical point [4,5]. It modifies the behavior of several thermodynamic and transport properties.…”

Section: Introductionmentioning

confidence: 99%

Study of the Transport Properties of the Critical Binary Mixture Triethylamine − Water with an Ionic Impurity

Toumi¹,

Hafaiedh²,

Bouanz

2022

Ukr. J. Phys.

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The binary liquid mixture of triethylamine + water (TEA–W) has a lower consolute point at a critical composition of 32.27 mass. % triethylamine. The shear viscosity (η) and the electrical conductivity (σ) in the single phase region of this system with added (K+, Cl–) ions at various concentrations are measured in the vicinity and far from the critical temperature TC. For the pure system without KCl salt, the viscosity measurements yield an enhancement, as expected, for the Ising criticality with a crossover to a regular behavior. Shear viscosity data are consistent with a power-law divergence η = η0(Qζ0)zt–y predicted by the mode-coupling and dynamic renormalization group theories. In the temperature range ∆T = TC – T < 2 ºC, the electrical conductivity (σ) exhibits a monotonous deviation from the Vogel–Fulcher–Tammann (VFT) behavior. This anomaly is described by a power law t1 –α, where t is the reduced temperature (T –TC)/TC, and α is the critical exponent of the specific heat anomaly at constant pressure. For the electrolyte mixtures, the obtained critical exponent values are in the range of those expected by the theoretical calculations for the Ising 3D universality class. By combining the viscosity and the electrical conductivity data, the value of the computed Walden product has been determined, and the salt dissociation degrees, as well as the Debye screening length, have been estimated.

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Coexistence curves of the binary mixture isobutyric acid–water with added ions (K+,Cl−)

Cited by 32 publications

References 13 publications

Shift of the Critical Mixing Temperature in Strong Electric Fields. Theory and Experiment

Shift of the Critical Mixing Temperature in Strong Electric Fields. Theory and Experiment

Reaction Kinetics and Critical Phenomena: Iodination of Acetone in Isobutyric Acid + Water near the Consolute Point

Study of the Transport Properties of the Critical Binary Mixture Triethylamine − Water with an Ionic Impurity

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