Excess partial molar entropy of alkane-mono-ols in aqueous solutions at 25°C

2003 ◽  
Vol 81 (2) ◽  
pp. 150-155 ◽  
Author(s):  
Yoshikata Koga ◽  
Peter Westh ◽  
Keiko Nishikawa
Keyword(s):  
Aqueous Solutions ◽  
Key Words ◽  
Preceding Paper ◽  
Aqueous Methanol ◽  
Model Free ◽  
Chemical Potentials ◽  
Hydrophobic Nature ◽  
Mixing Schemes ◽  
Partial Molar Entropy ◽  
Partial Molar Enthalpies

In the preceding paper, we reported the values of model-free chemical potentials for aqueous methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-hexanol at 25°C over the entire compositional region. Using alcohol excess partial molar enthalpies, HEAL, determined earlier in this laboratory (Can. J. Chem. 74, 713 (1996)), we have calculated excess partial molar entropies for the alcohols, SEAL, where AL stands for an alcohol. We then calculated, numerically, the entropic interaction, SEAL–AL = N([Formula: see text]SEAL/[Formula: see text]nAL)p,T,nW, where nAL is the amount of AL, nW is the amount of H2O, and N is the total amount of solution. SEAL–AL signifies the effect of addition of AL upon the entropic situation of existing AL in solution. Using these quantities, the mixing schemes in aqueous alcohols have been studied. The earlier conclusions, which used HEAL and HEAL–AL alone, are confirmed. Furthermore, the order of the relative hydrophobic nature of alcohols is established from the behaviour of SEAL–AL and of HEAL–AL as methanol < ethanol < 2-propanol < 1-propanol. Key Words: aqueous alcohols, excess partial molar entropies, entropic interaction mixing schemes, hydrophobicity ranking.

scholarly journals Excess partial molar enthalpies of alkane-mono-ols in aqueous solutions

1996 ◽  
Vol 74 (5) ◽  
pp. 713-721 ◽  
Author(s):  
Steven Hiroshi Tanaka ◽  
Hikari Infinity Yoshihara ◽  
Alice Wen-Chi Ho ◽  
Frankie W. Lau ◽  
Peter Westh ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Key Words ◽  
Mole Fraction ◽  
Composition Range ◽  
Hydrophobic Moiety ◽  
Enthalpic Interaction ◽  
Mixing Schemes ◽  
Small Increments ◽  
Partial Molar Enthalpies ◽  
Transition Of Mixing Scheme

Excess partial molar enthalpies, HAE, of methanol, ethanol, and 1- and 2-propanols in aqueous solutions were measured directly, accurately, and in small increments in mole fraction at 25 °C. From these data, the solute–solute enthalpic interactions, HAAE≡N(∂HAE/∂nA), were evaluated for each alcohol. These data indicate that three distinctively different mixing schemes, I, II, and III exist, as was the case for aqueous 2-butoxyethanol previously studied in our laboratory. The transition from mixing scheme I to II appears to take place gradually within a small composition range. As the hydrophobic moiety becomes smaller from 2-butoxyethanol to methanol, the locus of the transition moves to a higher value in mole fraction of the alcohol. At the same time, the range of transition becomes wider and the solute–solute enthalpic interaction weaker. Key words: excess partial molar enthalpies in aqueous solutions, methanol, ethanol, 1-propanol, 2-propanol, enthalpic interaction, transition of mixing scheme.

Transfer chemical potentials for iron(II)-diimine complexes from water into aqueous methanol

1984 ◽  
Vol 9 (8) ◽  
pp. 306-308 ◽  
Author(s):  
Ezz -Eldin A. Abu-Gharib ◽  
Michael J. Blandamer ◽  
John Burgess ◽  
Nrinder Gosal ◽  
Pilar Guardado ◽  
...  
Keyword(s):  
Aqueous Methanol ◽  
Chemical Potentials ◽  
Diimine Complexes

An Improved Equation for the Liquid Junction Potential at the Interface of Different Solvents

1992 ◽  
Vol 45 (10) ◽  
pp. 1633 ◽  
Author(s):  
A Berne ◽  
C Kahanda ◽  
O Popovych
Keyword(s):  
Mixed Solvent ◽  
Electrolyte Solutions ◽  
Transport Numbers ◽  
Liquid Junction Potential ◽  
Aqueous Methanol ◽  
Liquid Junction ◽  
Chemical Potentials ◽  
Solvent Dependence ◽  
New Equation ◽  
Junction Potential

The component of the liquid-junction potential due to the diffusion of ions across an interface of electrolyte solutions in different solvents was formulated by taking into account the solvent dependence of the transport numbers, t, and of the chemical potentials of ions in the interphase region as determined from experimental data on their variation in the mixed-solvent compositions. The new equation was applied to NaCl/NaCl and HCl/HCl junctions between water and methanol-water solvents over the entire solvent range. Significant differences between the results obtained with the new equation and the old formulation, which treated the transport numbers as solvent-independent, were observed only for the HCl junctions involving 90-100 wt % aqueous methanol, where tH exhibits a sharp minimum as a function of the solvent composition.

The metachors of polyvalent and associated electrolytes in aqueous solutions

1984 ◽  
Vol 49 (5) ◽  
pp. 1079-1089
Author(s):  
Jiří Čeleda ◽  
Stanislav Škramovský ◽  
Jana Žilková
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Oxalic Acid ◽  
Organic Acids ◽  
Aqueous Solutions ◽  
Preceding Paper ◽  
Weak Electrolytes ◽  
Direct Proportionality ◽  
Very High

The quantity metachor introduced in the preceding paper was evaluated from the experimental data on surface tension of the aqueous solutions for a set of polyvalent and weak electrolytes. The almost complete concentration independence of the metachor and its direct proportionality to the number of the free charges in a dissociated molecule (observed and theoretically substantiated in the above cited paper for strong 1,1-, 1,2- and 2,1-valent electrolytes) has been verified in the present paper also for electrolytes of the higher valency types. The metachor values of fully dissociated 1,1-, 1,2-, 1,3- and 1,4-valent electrolytes follow a ratio (5 ± 1) : (10 ± 1.5) : 15 : 22 cm3 mol-1. Association of the electrolytes decreases correspondingly the metachor value as one can see on the case of electrolytes with bulky ions (NH4SCN, KCH3COO, Na2S2O3, hexacyanoferrates(II) or with the free acids H2SO4, H2CrO4, H3PO4 etc. A weak, in the investigated concentration range neglibility dissociated oxalic acid, consisting of small hydrated hydrophilic molecules, exhibits metachor values close to zero. Dibasic organic acids with a larger number of hydrophobic CH2 groups reach very high negative metachor values, however, their salts again possess metachor values close to 10 cm3 mol-1 - in accordance with the values found for strong 1,2-valent electrolytes. The metachors of ZnCl2 and CdCl2 decrease sharply from the last mentioned value, with increasing concentration while the metachor value of zinc perchlorate remains unchanged at the level corresponding to the fully dissociated salt. This is in agreement with the well known sequence of tendency of the d10-cations to form complexes with the Cl- and ClO-4 anions. All these facts have verified that the metachor can be, in principle, applied for a diagnostic states of the electrolytes in aqueous solutions.

Ionic conductivity in the water-rich region of aqueous 2-butoxyethanol

1995 ◽  
Vol 73 (8) ◽  
pp. 1294-1297 ◽  
Author(s):  
Yoshikata Koga ◽  
Virginia J. Loo ◽  
Kataryna T. Puhacz
Keyword(s):  
Hydrogen Bond ◽  
Ionic Conductivity ◽  
Aqueous Solutions ◽  
Infinite Dilution ◽  
Ionic Conductivities ◽  
Molar Conductivity ◽  
Hydrogen Bond Network ◽  
Rich Region ◽  
Mixing Schemes ◽  
Bond Network

Ionic conductivities of HCl, KOH, and KCl were measured in aqueous solutions of 2-butoxyethanol (BE) at 25 °C. The quantity, Λj′ = σ/xj, which is almost proportional to the molar conductivity, was extrapolated to the infinite dilution xj → 0. σ is the conductivity and xj is the mole fraction of j(= HCl, KOH, or KCl). The plots of 0Λj′, the value of Λj′ extrapolated to infinite dilution, against xBE showed a change in slope at xBE = 0.0175. The previous work from this laboratory indicated that the mixing scheme changes qualitatively at the same locus, xBE = 0.0175. By mixing scheme we simply mean the way in which BE and H2O molecules mix with each other. Assuming additivity in 0Λj′ in terms of constituent ions, those values for H+OH− were calculated. Plots of [Formula: see text] thus calculated as a function of xBE in the water-rich region, 0 < xBE < 0.0175, suggest that the hydrogen bond probability decreases in the bulk of solution, as xBE increases. Keywords: aqueous 2-butoxyethanol, ionic conductivities, mixing schemes, hydrogen bond network.

Thermodynamic properties of peptide solutions. The relative partial molar enthalpies of aqueous solutions of glycylglycylglycine, glycylglycylalanine and alanylglycylglycine

1983 ◽  
Vol 36 (9) ◽  
pp. 1813 ◽  
Author(s):  
MK Kumaran ◽  
ID Watson ◽  
GR Hedwig
Keyword(s):  
Thermodynamic Properties ◽  
Aqueous Solutions ◽  
Side Chain ◽  
Enthalpies Of Dilution ◽  
Flow Microcalorimetry ◽  
Water Side ◽  
Partial Molar Enthalpies

The enthalpies of dilution at 298 K of aqueous solutions of the tripeptides glycylglycylglycine, glycylglycylalanine and alanylglycylglycine have been determined by flow microcalorimetry. From these data the partial molar enthalpies of the solvent in the solutions have been calculated. The results indicate that water side-chain interactions make an important contribution to the solvation of peptides.

Excess chemical potentials, partial molar enthalpies and entropies in binary aqueous acetone and tetramethyl urea at 25°C

2000 ◽  
Vol 175 (1-2) ◽  
pp. 35-43 ◽  
Author(s):  
Daniel H.C Chen ◽  
Pui Ming Chu ◽  
Steven Hiroshi Tanaka ◽  
Eric C.H To ◽  
Yoshikata Koga
Keyword(s):  
Aqueous Acetone ◽  
Chemical Potentials ◽  
Partial Molar Enthalpies
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