We studied the hydration characteristics of room-temperature ionic liquids (IL). experimentally determined excess chemical potentials, , partial molar enthalpies, and entropies in IL−H2O systems at 25 °C. The were 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) iodide ([bmim]I). From these data, (integral) enthalpy entropy, IL−IL enthalpic interaction, calculated. Using thermodynamic we deduced mixing schemes, or "solution structures", systems. At infinite dilution IL dissociates...

Thermodynamic studies were carried out on aqueous solutions of some nonelectrolytes. The quantities proportional to the second derivatives Gibbs energy measured directly and in small increments mole fraction or temperature. Therefore, we able differentiate once more with respect Generally, higher order derivative, detailed information it contains. Using these third derivatives, an attempt was made at elucidating mixing schemes, way which solute solvent H2O molecules mix each other. For...

The excess partial molar enthalpy of 1-propanol (1P), , was measured at 28 degrees C in the ternary mixture 1P-1-butyl-3-methylimidazolium chloride ([bmim]Cl)-H(2)O H(2)O-rich composition range. From these data we evaluated what call 1P-1P enthalpic interaction function, . Its changes induced by addition [bmim]Cl pattern were used as a probe to elucidate effect on molecular organization H(2)O. It found that Cl(-) not conspicuous within this methodology, and observed dependence is...

1-Butyl-3-methylimidazolium bromide ([bmim]Br) and its chloride ([bmim]Cl) are representative prototypes of ionic liquids. We investigated the melting freezing behaviors [bmim]Br [bmim]Cl by using a homemade differential scanning calorimeter (DSC) with nano-Watt stability sensitivity. The measurements were carried out at heating cooling rates slow enough to mimic quasi-static processes. Their thermal show characteristic features such as wide pre-melting range excessive supercooling...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcess partial molar free energies and entropies in aqueous tert-butyl alcohol solutions at 25.degree.CYoshikata. Koga, William W. Y. Siu, Terrance H. WongCite this: J. Phys. Chem. 1990, 94, 19, 7700–7706Publication Date (Print):September 1, 1990Publication History Published online1 May 2002Published inissue 1 September 1990https://pubs.acs.org/doi/10.1021/j100382a070https://doi.org/10.1021/j100382a070research-articleACS PublicationsRequest reuse...

We showed recently that low entropy core/shell structured nanoparticles form spontaneously from the physical mixture of a dispersion Ag and another noble metal (Rh, Pd, or Pt) at room temperature. Here we use isothermal titration calorimetry (ITC) show initial step such spontaneous process is strongly exothermic. When alcohol poly(N-vinyl-2-pyrrolidone) (PVP)-protected Rh (average diameter 2.3 nm) was titrated into alcoholic PVP-protected nanoparticles, strong exothermic enthalpy change,...

Excess partial molar enthalpies of tert-butanol (TBA) in water–tert-butanol mixtures were measured at 20.00, 26.90, 45.17, and 59.49 °C the water-rich region, 30.00 for entire range. The results together with those previous work, (Y. Koga. Can. J. Chem. 64, 206 (1986)), appear to support following views: At X TBA ≈ 0, molecules form hydrogen bonds H 2 O molecules, they enhance structure bond network O. latter effect is very long range; enthalpic repulsion between solutes already operative...

The Kirkwood-Buff integrals of some binary aqueous alcohol mixtures are computed from the available vapor pressure measurements and compared with previous results as well small angle neutron scattering experiments. emphasis present report is on accuracy that can be achieved by these two different types measurements. This seems to needed, mainly in view discrepancies between various published results, shown herein. It argued agreement peak positions more important than magnitude. In general,...

The classical concept of "iceberg formation" is modified by our recent thermodynamic studies. local enhancement the hydrogen-bond network H2O in immediate vicinity small nonelectrolyte solutes (i.e., formation") still correct. However, probability bulk away from reduced progressively, as solute composition increases. When to bond percolation threshold hexagonal ice connectivity, lost and a qualitatively different mixing scheme sets in, whereby solution consists two kinds clusters. In...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVapor pressures of aqueous 2-butoxyethanol solutions at 25.degree.C: transitions in mixing schemeYoshikata KogaCite this: J. Phys. Chem. 1991, 95, 10, 4119–4126Publication Date (Print):May 1, 1991Publication History Published online1 May 2002Published inissue 1 1991https://pubs.acs.org/doi/10.1021/j100163a041https://doi.org/10.1021/j100163a041research-articleACS PublicationsRequest reuse permissionsArticle Views183Altmetric-Citations60LEARN ABOUT...

Excess partial molar enthalpies, H A E , of methanol, ethanol, and 1- 2-propanols in aqueous solutions were measured directly, accurately, small increments mole fraction at 25 °C. From these data, the solute–solute enthalpic interactions, AA ≡N(∂H /∂n ), evaluated for each alcohol. These data indicate that three distinctively different mixing schemes, I, II, III exist, as was case 2-butoxyethanol previously studied our laboratory. The transition from scheme I to II appears take place...

We study the mixing schemes or molecular processes occurring in aqueous acetonitrile (ACN) and acetone (ACT) by near-infrared spectroscopy (NIR). Both solutions (any other solutions) are not free from strong complex intermolecular interactions. To tackle such a many-body problem, we first use concept of excess molar absorptivity, epsilonE, which is function solute mole fraction addition to that wavenumber, nu. The plots epsilonE calculated NIR spectra for both against nu showed two clearly...

We have developed what we call the 1-propanol(1P) probing methodology. By using it, determined relative hydrophobicity/hydrophilicity indices of 2-butoxyethanol, a typical hydrophobe; urea, hydrophile; and trimethylamine-N-oxide, an amphiphile. comparing these with those for other solutes studied earlier, including tetramethyl tetramethylammonium ion, mono-ols, polyols, suggest that methyl groups attached to N atom, or N-methyl groups, do not promote hydrophobicity but, rather, enhance...

The wording "hydrophobicity/hydrophilicity" has been used in a loose manner based on human experiences. We have devised more quantitative way to redefine "hydrophobes" and "hydrophiles" terms of the mole fraction dependence pattern one third derivative quantities, enthalpic interaction between solute molecules. then thermodynamic methodology characterize effect H2O its hydrophobicity and/or hydrophilicity. use signature, 1-propanol, HE1P1P, monitor how test modifies H2O. By this method,...

Excess partial molar enthalpies of 2-butoxyethanol (BE) and water, [Formula: see text](I = BE or H 2 O), were measured from 25 to 35 °C in the entire concentration range. The results indicated that there are three regions bounded at about x B 0.02 0.5, being mole fraction BE. In each region, temperature dependence text] (I is distinctively different those other regions, appears support following views: water-rich < 0.02, molecules cause an enhancement structure this effect spans a long...

We investigated the effects of NaF, NaCl, NaBr, and NaI on molecular organization H2O by a calorimetric methodology developed us earlier. use third derivative quantities G pertaining to 1-propanol (1P) in ternary 1P−a salt−H2O as probe elucidate salt H2O. found that NaF NaCl worked hydration centers. The numbers were 19 ± 2 for 7.5 0.6 NaCl. Furthermore, bulk away from shell was unaffected presence Na+, F-, Cl-. For NaBr NaI, addition Br- I- acted like hydrophilic moiety such urea. Namely,...

Adsorption isotherms and heats of adsorption have been determined for the methane–graphite system over wide ranges temperature surface coverage. Some data are reported region below monolayer coverage where liquid vapour phases coexist but majority pertain to multilayer adsorption. The fluid–incommensurate-solid transition has examined in detail an analysis results yields a tricritical 105 K order parameter exponent 1/3. An explanation is given unexpected difference dependence isosteric heat...

The excess partial molar enthalpy of 1-propanol (1P),, was experimentally measured in ternary 1P-[NaPF6, NaCF3SO3 (OTF) or NaN(SO2CF3)2 (TFSI)]-H2O system. From thedata, the enthalpic 1P−1P interaction function,, which is compositional derivative of, evaluated graphically. On addition Na salt, x1P-dependence pattern ofshowed a characteristic change. This induced change used as probe to elucidate effect sample Na-salt on H2O. Because we know Na+ from our previous work, show that each anion...