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Sandra C. Greer - One of the best experts on this subject based on the ideXlab platform.
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Partitioning of Poly(ethylene oxide), Poly(ethylene imide), and Bovine Serum Albumin in Isobutyric Acid + Water
Macromolecules, 2008Co-Authors: Alexander I Norman, Brittney A Manvilla, Evan L Frank, Justine N Niamke, Grant D Smith, Sandra C. GreerAbstract:We present new measurements of the partitioning of the polymers (poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI)) and the protein bovine serum albumin (BSA) between coexisting liquid phases of Isobutyric Acid + water. We show that all partition unevenly between the liquid phases: In all cases, there is substantially more polymer or protein in the upper, Isobutyric Acid-rich phase. At molecular masses above about 10 kg/mol, PEG and PEI fractionate between the liquid phases, with a higher average molecular mass in the lower, water-rich phase. The fractionation and partitioning are amplified both when the molecular mass of the polymer is increased, and when D2O + Isobutyric Acid is used instead of H2O + Isobutyric Acid. The dependence of the distribution coefficient on molecular mass disagrees with the predictions of Flory−Huggins mean field theory for all PEG and PEI systems studied. At low molecular weight, the PEG fractionations are consistent with theoretical predictions that the molecular ma...
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partitioning of poly ethylene oxide poly ethylene imide and bovine serum albumin in Isobutyric Acid water
Macromolecules, 2008Co-Authors: Alexander I Norman, Brittney A Manvilla, Evan L Frank, Justine N Niamke, Grant D Smith, Sandra C. GreerAbstract:We present new measurements of the partitioning of the polymers (poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI)) and the protein bovine serum albumin (BSA) between coexisting liquid phases of Isobutyric Acid + water. We show that all partition unevenly between the liquid phases: In all cases, there is substantially more polymer or protein in the upper, Isobutyric Acid-rich phase. At molecular masses above about 10 kg/mol, PEG and PEI fractionate between the liquid phases, with a higher average molecular mass in the lower, water-rich phase. The fractionation and partitioning are amplified both when the molecular mass of the polymer is increased, and when D2O + Isobutyric Acid is used instead of H2O + Isobutyric Acid. The dependence of the distribution coefficient on molecular mass disagrees with the predictions of Flory−Huggins mean field theory for all PEG and PEI systems studied. At low molecular weight, the PEG fractionations are consistent with theoretical predictions that the molecular ma...
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partitioning fractionation and conformations of star poly ethylene glycol in Isobutyric Acid and water
Macromolecules, 2007Co-Authors: Alexander I Norman, Derek L Ho, Sandra C. GreerAbstract:We investigate the partitioning, fractionation, and conformations of star poly(ethylene glycol) (PEG) in coexisting liquid phases of Isobutyric Acid and water. Star PEG does partition: 98% in the upper Isobutyric Acid phase, versus 80−90% for linear PEG. There is no significant fractionation of the star PEG for molecular masses less than or equal to 10 kg/mol, but fractionation may occur at higher molecular masses. Small angle neutron scattering shows that the arms of the star PEG molecules form coils in D2O but form stiff rods in deuterated Isobutyric Acid. At higher average molecular masses (>4 kg/mol) and higher temperatures (60 °C), some arms are coils and some are rods in Isobutyric Acid. Polarimetry studies indicate that these “rodlike” arms are actually helical conformations. At a star molecular mass of 2 kg/mol, the helical arms persist above 70 °C, but at larger molecular masses, the helical arms revert to coils at temperatures around 75 °C. The addition of PEG to Isobutyric Acid and H2O increas...
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conformational change of poly ethylene glycol near the critical point of Isobutyric Acid water
Journal of Physical Chemistry B, 2006Co-Authors: Patricia Castellanos, Alexander I Norman, Sandra C. GreerAbstract:In solutions of Isobutyric Acid + water, poly(ethylene glycol) (PEG) can assume a helical conformation. [Alessi, M. L.; Norman, A. I.; Knowlton, S. E.; Ho, D. L.; Greer, S. C. Macromolecules 2005, 35, 9333-9340.] Here we report new measurements of the kinematic viscosity, v, as a function of temperature for a solution of Isobutyric Acid + water at the critical composition, to which PEG (number average molecular weight = 1.01 ×10 3 g/mol) was added at a concentration of 6.01 mg/mL. The data show that v decreases near the critical point, with a maximum in v at about 0.05 °C above the critical temperature, T c . We interpret this change in v in terms of a change in conformation of the polymer from helix to coil. This interpretation is supported by polarimetry measurements on the same mixture doped with (S)-(+)-1,2-propanediol, which indicates the loss of helicity near T c and also a second helix-to-coil transition at about 60 °C.
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Conformational change of poly(ethylene glycol) near the critical point of Isobutyric Acid + water.
Journal of Physical Chemistry B, 2006Co-Authors: Patricia Castellanos, Alexander I Norman, Sandra C. GreerAbstract:In solutions of Isobutyric Acid + water, poly(ethylene glycol) (PEG) can assume a helical conformation. [Alessi, M. L.; Norman, A. I.; Knowlton, S. E.; Ho, D. L.; Greer, S. C. Macromolecules 2005, 35, 9333-9340.] Here we report new measurements of the kinematic viscosity, v, as a function of temperature for a solution of Isobutyric Acid + water at the critical composition, to which PEG (number average molecular weight = 1.01 ×10 3 g/mol) was added at a concentration of 6.01 mg/mL. The data show that v decreases near the critical point, with a maximum in v at about 0.05 °C above the critical temperature, T c . We interpret this change in v in terms of a change in conformation of the polymer from helix to coil. This interpretation is supported by polarimetry measurements on the same mixture doped with (S)-(+)-1,2-propanediol, which indicates the loss of helicity near T c and also a second helix-to-coil transition at about 60 °C.
M. Bouanz - One of the best experts on this subject based on the ideXlab platform.
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Excess permittivity and excess conductivity of binary fluid mixture Isobutyric Acid – water along the coexistence curve
Physics and Chemistry of Liquids, 2009Co-Authors: N. Hadded, M. BouanzAbstract:Excess permittivity and excess conductivity of the binary fluid mixture Isobutyric Acid–water (I–W) have been computed at three temperatures and along the coexistence curve, on the basis of refractive index and electrical conductivity data of the mixture. The other related properties, molar volume, molar refraction and polarisablities have also been reported. The temperature dependence of the molar refraction was also examined. The results have been interpreted in terms of the nature of specific intermolecular interactions between the components.
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excess permittivity and excess conductivity of binary fluid mixture Isobutyric Acid water along the coexistence curve
Physics and Chemistry of Liquids, 2009Co-Authors: N. Hadded, M. BouanzAbstract:Excess permittivity and excess conductivity of the binary fluid mixture Isobutyric Acid–water (I–W) have been computed at three temperatures and along the coexistence curve, on the basis of refractive index and electrical conductivity data of the mixture. The other related properties, molar volume, molar refraction and polarisablities have also been reported. The temperature dependence of the molar refraction was also examined. The results have been interpreted in terms of the nature of specific intermolecular interactions between the components.
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Electrical conductivity of the binary mixture Isobutyric Acid–water with added (Zn2+, SO42−) ions
Fluid Phase Equilibria, 2008Co-Authors: N. Hadded, M. BouanzAbstract:Abstract Precise electrical conductivity σ (mS cm−1) measurements for Isobutyric Acid–water mixtures with added Zn2+ and SO42− ions have been performed in the Arrhenius temperature domain of the studied electrolyte and for different fractional composition of IBA in the range from 16 mass% to 80 mass%. The temperature dependence of the electrical conductivity of the studied mixtures obeys Arrhenius law over the whole range of investigated parameters. The behaviour of the electrical conductivity of an electrolyte depends on the ZnSO4 salt concentration. A continuous but very drastic decrease of the electrical conductivity is observed for compositions in Isobutyric Acid exceeding the critical composition. Comparing the electrical conductivity of electrolytic systems (IBA–W) + ZnSO4 and (IBA–W) + KCl at a given salt concentration and IBA composition, one can note that the mobility of (K+, Cl−1) ions is greater than that of (Zn2+, SO42−) over the whole range of investigated parameters.
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electrical conductivity along phase diagram of the critical mixture Isobutyric Acid water with added k cl ions
International Journal of Molecular Sciences, 2003Co-Authors: Emna Cherif, M. BouanzAbstract:Three systems, Isobutyric Acid – water (I–W), “(I-W) + 5 10-4 M (KCl)” and “(IW) + 5 10-3 M (KCl)”, have been studied by measuring the electrical conductivity σ (Ω-1cm-1) along the coexistence curve in a single phase, as a function of the variations temperature T and composition X in Acid. The coefficient σ is a temperature dependent parameter for ions, increasing as temperature is elevated. Contrary to the visconty, the electrical conductivity does not show any anomaly in the critical region.
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coexistence curves of the binary mixture Isobutyric Acid water with added ions k cl
Chemical Physics Letters, 2002Co-Authors: A Toumi, M. Bouanz, A GharbiAbstract:Abstract Measurement of the coexistence curve of the binary mixture Isobutyric Acid–water (I–W) with increasing amounts of ions impurity showed essentially a linear dependence of the critical temperature and critical composition with concentration of (K + ,Cl − ) ions. Each coexistence curve of the electrolyte mixture is characterized by a new effective critical exponent β =(0.251−0.771) is neither compatible with the Ising value β =0.325. The experimental technique used here is the visual method.
James K Baird - One of the best experts on this subject based on the ideXlab platform.
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a chemical test of critical point isomorphism reactive dissolution of ionic solids in Isobutyric Acid water near the consolute point
Journal of Physical Chemistry B, 2015Co-Authors: James K Baird, Baichuan Hu, Jonathan D Baker, Joshua R Lang, Karen E Joyce, Alison K Sides, Randi D RicheyAbstract:Binary liquid mixtures having a consolute point can be used as solvents for chemical reactions. When excess cerium(IV) oxide is brought into equilibrium with a mixture of Isobutyric Acid + water, and the concentration of cerium in the liquid phase is plotted in van’t Hoff form, a straight line results for temperatures sufficiently in excess of the critical solution temperature. Within 1 K of the critical temperature, however, the concentration becomes substantially suppressed, and the van’t Hoff slope diverges toward negative infinity. According to the phase rule, one mole fraction can be fixed. Given this restriction, the temperature behavior of the data is in exact agreement with the predictions of both the principle of critical point isomorphism and the Gibbs–Helmholtz equation. In addition, we have determined the concentration of lead in the liquid phase when crystalline lead(II) sulfate reacts with potassium iodide in Isobutyric Acid + water. When plotted in van’t Hoff form, the data lie on a straigh...
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A Chemical Test of Critical Point Isomorphism: Reactive Dissolution of Ionic Solids in Isobutyric Acid + Water near the Consolute Point
Journal of Physical Chemistry B, 2015Co-Authors: James K Baird, Baichuan Hu, Jonathan D Baker, Joshua R Lang, Karen E Joyce, Alison K Sides, Randi D RicheyAbstract:Binary liquid mixtures having a consolute point can be used as solvents for chemical reactions. When excess cerium(IV) oxide is brought into equilibrium with a mixture of Isobutyric Acid + water, and the concentration of cerium in the liquid phase is plotted in van’t Hoff form, a straight line results for temperatures sufficiently in excess of the critical solution temperature. Within 1 K of the critical temperature, however, the concentration becomes substantially suppressed, and the van’t Hoff slope diverges toward negative infinity. According to the phase rule, one mole fraction can be fixed. Given this restriction, the temperature behavior of the data is in exact agreement with the predictions of both the principle of critical point isomorphism and the Gibbs–Helmholtz equation. In addition, we have determined the concentration of lead in the liquid phase when crystalline lead(II) sulfate reacts with potassium iodide in Isobutyric Acid + water. When plotted in van’t Hoff form, the data lie on a straigh...
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Critical-point universality in adsorption: the effect of charcoal on a mixture of Isobutyric Acid and water near the consolute point.
Physical review. E Statistical nonlinear and soft matter physics, 2011Co-Authors: Timothy J Giesy, Alan S Chou, Robert L Mcfeeters, James K Baird, Douglas A BarlowAbstract:The mixture of Isobutyric Acid and water has a consolute point at a temperature of 25.75 °C and mole fraction 0.1148 Isobutyric Acid. When charcoal is added to this mixture, the concentration of Isobutyric Acid is reduced by adsorption. We have measured the action of charcoal on solutions of Isobutyric Acid and water as a function of Isobutyric Acid mole fraction at temperatures of 25.85 and 32.50 °C. At the higher temperature, the specific adsorption density (y(2)(α)/m) satisfies the Freundlich equation (y(2)(α)/m)=KX(2)(1/n), where y(2)(α) is the mass of Isobutyric Acid adsorbed, m is the mass of charcoal, X(2) is the equilibrium mole fraction of Isobutyric Acid, n is the Freundlich index, and K=K(T) is an amplitude that depends upon the temperature T. At 25.85 °C, a critical endpoint is located at an Isobutyric Acid mole fraction X(2)(ce)=0.09. When compared with the Freundlich equation at this temperature, a plot of the specific adsorption density as a function of X(2) in the vicinity of the critical-endpoint composition assumes a shape which is reminiscent of the derivative of a Dirac delta function. Using critical-point scaling theory, we show that this divergent pattern is consistent with the principle of critical point universality.
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A chemical test of the principle of critical point universality: the solubility of nickel (II) oxide in Isobutyric Acid + water near the consolute point.
Journal of Chemical Physics, 2011Co-Authors: Baichuan Hu, James K Baird, Randi D Richey, Ramana G ReddyAbstract:A mixture of Isobutyric Acid + water has an upper consolute point at 38.8 mass % Isobutyric Acid and temperature near 26 °C. Nickel (II) oxide dissolves in this mixture by reacting with the Acid to produce water and nickel isobutyrate. The solubility of nickel (II) oxide in Isobutyric Acid + water has been measured as a function of temperature at compositions, 25, 38.8, and 60 mass % Isobutyric Acid. For values of the temperature, T, which were at least 2 K in excess of the liquid–liquid phase transition temperature, the measured values of the solubility, s, lie on a straight line when plotted in van't Hoff form with ln s versus 1/T. The slope, (∂ln s/∂(1/T)), of the line is negative indicating that the dissolution reaction is endothermic. When the temperature was within 2 K of the phase transition temperature, however, (∂ln s/∂(1/T)) diverged toward negative infinity. The principle of critical point universality predicts that when excess solid nickel (II) oxide is in dissolution equilibrium with liquid i...
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a chemical test of the principle of critical point universality the solubility of nickel ii oxide in Isobutyric Acid water near the consolute point
Journal of Chemical Physics, 2011Co-Authors: Baichuan Hu, James K Baird, Randi D Richey, Ramana G ReddyAbstract:A mixture of Isobutyric Acid + water has an upper consolute point at 38.8 mass % Isobutyric Acid and temperature near 26 °C. Nickel (II) oxide dissolves in this mixture by reacting with the Acid to produce water and nickel isobutyrate. The solubility of nickel (II) oxide in Isobutyric Acid + water has been measured as a function of temperature at compositions, 25, 38.8, and 60 mass % Isobutyric Acid. For values of the temperature, T, which were at least 2 K in excess of the liquid–liquid phase transition temperature, the measured values of the solubility, s, lie on a straight line when plotted in van't Hoff form with ln s versus 1/T. The slope, (∂ln s/∂(1/T)), of the line is negative indicating that the dissolution reaction is endothermic. When the temperature was within 2 K of the phase transition temperature, however, (∂ln s/∂(1/T)) diverged toward negative infinity. The principle of critical point universality predicts that when excess solid nickel (II) oxide is in dissolution equilibrium with liquid i...
Alexander I Norman - One of the best experts on this subject based on the ideXlab platform.
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Partitioning of Poly(ethylene oxide), Poly(ethylene imide), and Bovine Serum Albumin in Isobutyric Acid + Water
Macromolecules, 2008Co-Authors: Alexander I Norman, Brittney A Manvilla, Evan L Frank, Justine N Niamke, Grant D Smith, Sandra C. GreerAbstract:We present new measurements of the partitioning of the polymers (poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI)) and the protein bovine serum albumin (BSA) between coexisting liquid phases of Isobutyric Acid + water. We show that all partition unevenly between the liquid phases: In all cases, there is substantially more polymer or protein in the upper, Isobutyric Acid-rich phase. At molecular masses above about 10 kg/mol, PEG and PEI fractionate between the liquid phases, with a higher average molecular mass in the lower, water-rich phase. The fractionation and partitioning are amplified both when the molecular mass of the polymer is increased, and when D2O + Isobutyric Acid is used instead of H2O + Isobutyric Acid. The dependence of the distribution coefficient on molecular mass disagrees with the predictions of Flory−Huggins mean field theory for all PEG and PEI systems studied. At low molecular weight, the PEG fractionations are consistent with theoretical predictions that the molecular ma...
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partitioning of poly ethylene oxide poly ethylene imide and bovine serum albumin in Isobutyric Acid water
Macromolecules, 2008Co-Authors: Alexander I Norman, Brittney A Manvilla, Evan L Frank, Justine N Niamke, Grant D Smith, Sandra C. GreerAbstract:We present new measurements of the partitioning of the polymers (poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI)) and the protein bovine serum albumin (BSA) between coexisting liquid phases of Isobutyric Acid + water. We show that all partition unevenly between the liquid phases: In all cases, there is substantially more polymer or protein in the upper, Isobutyric Acid-rich phase. At molecular masses above about 10 kg/mol, PEG and PEI fractionate between the liquid phases, with a higher average molecular mass in the lower, water-rich phase. The fractionation and partitioning are amplified both when the molecular mass of the polymer is increased, and when D2O + Isobutyric Acid is used instead of H2O + Isobutyric Acid. The dependence of the distribution coefficient on molecular mass disagrees with the predictions of Flory−Huggins mean field theory for all PEG and PEI systems studied. At low molecular weight, the PEG fractionations are consistent with theoretical predictions that the molecular ma...
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partitioning fractionation and conformations of star poly ethylene glycol in Isobutyric Acid and water
Macromolecules, 2007Co-Authors: Alexander I Norman, Derek L Ho, Sandra C. GreerAbstract:We investigate the partitioning, fractionation, and conformations of star poly(ethylene glycol) (PEG) in coexisting liquid phases of Isobutyric Acid and water. Star PEG does partition: 98% in the upper Isobutyric Acid phase, versus 80−90% for linear PEG. There is no significant fractionation of the star PEG for molecular masses less than or equal to 10 kg/mol, but fractionation may occur at higher molecular masses. Small angle neutron scattering shows that the arms of the star PEG molecules form coils in D2O but form stiff rods in deuterated Isobutyric Acid. At higher average molecular masses (>4 kg/mol) and higher temperatures (60 °C), some arms are coils and some are rods in Isobutyric Acid. Polarimetry studies indicate that these “rodlike” arms are actually helical conformations. At a star molecular mass of 2 kg/mol, the helical arms persist above 70 °C, but at larger molecular masses, the helical arms revert to coils at temperatures around 75 °C. The addition of PEG to Isobutyric Acid and H2O increas...
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conformational change of poly ethylene glycol near the critical point of Isobutyric Acid water
Journal of Physical Chemistry B, 2006Co-Authors: Patricia Castellanos, Alexander I Norman, Sandra C. GreerAbstract:In solutions of Isobutyric Acid + water, poly(ethylene glycol) (PEG) can assume a helical conformation. [Alessi, M. L.; Norman, A. I.; Knowlton, S. E.; Ho, D. L.; Greer, S. C. Macromolecules 2005, 35, 9333-9340.] Here we report new measurements of the kinematic viscosity, v, as a function of temperature for a solution of Isobutyric Acid + water at the critical composition, to which PEG (number average molecular weight = 1.01 ×10 3 g/mol) was added at a concentration of 6.01 mg/mL. The data show that v decreases near the critical point, with a maximum in v at about 0.05 °C above the critical temperature, T c . We interpret this change in v in terms of a change in conformation of the polymer from helix to coil. This interpretation is supported by polarimetry measurements on the same mixture doped with (S)-(+)-1,2-propanediol, which indicates the loss of helicity near T c and also a second helix-to-coil transition at about 60 °C.
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Conformational change of poly(ethylene glycol) near the critical point of Isobutyric Acid + water.
Journal of Physical Chemistry B, 2006Co-Authors: Patricia Castellanos, Alexander I Norman, Sandra C. GreerAbstract:In solutions of Isobutyric Acid + water, poly(ethylene glycol) (PEG) can assume a helical conformation. [Alessi, M. L.; Norman, A. I.; Knowlton, S. E.; Ho, D. L.; Greer, S. C. Macromolecules 2005, 35, 9333-9340.] Here we report new measurements of the kinematic viscosity, v, as a function of temperature for a solution of Isobutyric Acid + water at the critical composition, to which PEG (number average molecular weight = 1.01 ×10 3 g/mol) was added at a concentration of 6.01 mg/mL. The data show that v decreases near the critical point, with a maximum in v at about 0.05 °C above the critical temperature, T c . We interpret this change in v in terms of a change in conformation of the polymer from helix to coil. This interpretation is supported by polarimetry measurements on the same mixture doped with (S)-(+)-1,2-propanediol, which indicates the loss of helicity near T c and also a second helix-to-coil transition at about 60 °C.
Randi D Richey - One of the best experts on this subject based on the ideXlab platform.
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a chemical test of critical point isomorphism reactive dissolution of ionic solids in Isobutyric Acid water near the consolute point
Journal of Physical Chemistry B, 2015Co-Authors: James K Baird, Baichuan Hu, Jonathan D Baker, Joshua R Lang, Karen E Joyce, Alison K Sides, Randi D RicheyAbstract:Binary liquid mixtures having a consolute point can be used as solvents for chemical reactions. When excess cerium(IV) oxide is brought into equilibrium with a mixture of Isobutyric Acid + water, and the concentration of cerium in the liquid phase is plotted in van’t Hoff form, a straight line results for temperatures sufficiently in excess of the critical solution temperature. Within 1 K of the critical temperature, however, the concentration becomes substantially suppressed, and the van’t Hoff slope diverges toward negative infinity. According to the phase rule, one mole fraction can be fixed. Given this restriction, the temperature behavior of the data is in exact agreement with the predictions of both the principle of critical point isomorphism and the Gibbs–Helmholtz equation. In addition, we have determined the concentration of lead in the liquid phase when crystalline lead(II) sulfate reacts with potassium iodide in Isobutyric Acid + water. When plotted in van’t Hoff form, the data lie on a straigh...
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A Chemical Test of Critical Point Isomorphism: Reactive Dissolution of Ionic Solids in Isobutyric Acid + Water near the Consolute Point
Journal of Physical Chemistry B, 2015Co-Authors: James K Baird, Baichuan Hu, Jonathan D Baker, Joshua R Lang, Karen E Joyce, Alison K Sides, Randi D RicheyAbstract:Binary liquid mixtures having a consolute point can be used as solvents for chemical reactions. When excess cerium(IV) oxide is brought into equilibrium with a mixture of Isobutyric Acid + water, and the concentration of cerium in the liquid phase is plotted in van’t Hoff form, a straight line results for temperatures sufficiently in excess of the critical solution temperature. Within 1 K of the critical temperature, however, the concentration becomes substantially suppressed, and the van’t Hoff slope diverges toward negative infinity. According to the phase rule, one mole fraction can be fixed. Given this restriction, the temperature behavior of the data is in exact agreement with the predictions of both the principle of critical point isomorphism and the Gibbs–Helmholtz equation. In addition, we have determined the concentration of lead in the liquid phase when crystalline lead(II) sulfate reacts with potassium iodide in Isobutyric Acid + water. When plotted in van’t Hoff form, the data lie on a straigh...
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A chemical test of the principle of critical point universality: the solubility of nickel (II) oxide in Isobutyric Acid + water near the consolute point.
Journal of Chemical Physics, 2011Co-Authors: Baichuan Hu, James K Baird, Randi D Richey, Ramana G ReddyAbstract:A mixture of Isobutyric Acid + water has an upper consolute point at 38.8 mass % Isobutyric Acid and temperature near 26 °C. Nickel (II) oxide dissolves in this mixture by reacting with the Acid to produce water and nickel isobutyrate. The solubility of nickel (II) oxide in Isobutyric Acid + water has been measured as a function of temperature at compositions, 25, 38.8, and 60 mass % Isobutyric Acid. For values of the temperature, T, which were at least 2 K in excess of the liquid–liquid phase transition temperature, the measured values of the solubility, s, lie on a straight line when plotted in van't Hoff form with ln s versus 1/T. The slope, (∂ln s/∂(1/T)), of the line is negative indicating that the dissolution reaction is endothermic. When the temperature was within 2 K of the phase transition temperature, however, (∂ln s/∂(1/T)) diverged toward negative infinity. The principle of critical point universality predicts that when excess solid nickel (II) oxide is in dissolution equilibrium with liquid i...
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a chemical test of the principle of critical point universality the solubility of nickel ii oxide in Isobutyric Acid water near the consolute point
Journal of Chemical Physics, 2011Co-Authors: Baichuan Hu, James K Baird, Randi D Richey, Ramana G ReddyAbstract:A mixture of Isobutyric Acid + water has an upper consolute point at 38.8 mass % Isobutyric Acid and temperature near 26 °C. Nickel (II) oxide dissolves in this mixture by reacting with the Acid to produce water and nickel isobutyrate. The solubility of nickel (II) oxide in Isobutyric Acid + water has been measured as a function of temperature at compositions, 25, 38.8, and 60 mass % Isobutyric Acid. For values of the temperature, T, which were at least 2 K in excess of the liquid–liquid phase transition temperature, the measured values of the solubility, s, lie on a straight line when plotted in van't Hoff form with ln s versus 1/T. The slope, (∂ln s/∂(1/T)), of the line is negative indicating that the dissolution reaction is endothermic. When the temperature was within 2 K of the phase transition temperature, however, (∂ln s/∂(1/T)) diverged toward negative infinity. The principle of critical point universality predicts that when excess solid nickel (II) oxide is in dissolution equilibrium with liquid i...
