Molality Scale Research Articles

Raman Quantitative Measurement on the Cl− Molarity of H2O-NaCl-CO2 System: Application to Fluid Inclusions

In this study, Raman spectroscopy is applied to determine the salinity of fluid inclusions in the H2O-NaCl-CO2 system. In the work, various systems are prepared, such as H2O-NaCl, H2O-CO2, and H2O-NaCl-CO2. For the H2O-NaCl system, the addition of NaCl salts decreases the intensity of the sub-band below 3330 cm−1 but increases the intensity of the sub-band above 3330 cm−1. According to the structural analysis of the H2O-NaCl system, the spectral changes are mainly related to the interactions between Cl− and water. After the Raman OH stretching bands are fitted into two sub-bands, the intensity ratio between them is used to calculate the Cl− concentrations (molarity scale) of NaCl solutions. Additionally, based on the measured Raman spectra, the effects of CO2 on water structure may be weak. It is reasonable to ignore the impact of dissolved CO2 on Raman OH stretching bands. The procedure above can be extended to quantitatively determine the Cl− molarity of the H2O-NaCl-CO2 system. To demonstrate its reliability, this method is applied to determine the salinity of synthetic and natural fluid inclusions containing CO2.

Electrochemical behavior and electromotive force measurements of U3+/U0 in molten MgCl2-NaCl

The electrochemical behavior of UCl3 was investigated in molten MgCl2NaCl at 550 °C. Using electromotive force measurements, we have measured the formal reduction potential (Eo’) at 550 °C of U3+/U0 as +0.276 V vs. Mg/MgCl2 (-1.400 V vs. Ag/AgCl 5 mol%) on the molal scale. We also present the design and construction of a sealed Mg/MgCl2 reference electrode and have determined this system demonstrates ideal nonpolarizable electrode behavior, confirming it as an appropriate choice of reference electrode in molten chloride salts.

Retrospective rationalization of disparities between the concentration dependence of diffusion coefficients obtained by boundary spreading and dynamic light scattering.

This study establishes the existence of substantial agreement between published results from traditional boundary spreading measurements (including synthetic boundary measurements in the analytical ultracenrifuge) on two globular proteins (bovine serum albumin, ovalbumin) and the concentration dependence of diffusion coefficient predicted for experiments conducted under the operative thermodynamic constraints of constant temperature and solvent chemical potential. Although slight negative concentration dependence of the translational diffusion coefficient is the experimentally observed as well as theoretically predicted, the extent of the concentration dependence is within the limits of experimental uncertainty inherent in diffusion coefficient measurement. Attention is then directed toward the ionic strength dependence of the concentration dependence coefficient ([Formula: see text]) describing diffusion coefficients obtained by dynamic light scattering, where, in principle, the operative thermodynamic constraints of constant temperature and pressure preclude consideration of results in terms of single-solute theory. Nevertheless, good agreement between predicted and published experimental ionic strength dependencies of [Formula: see text] for lysozyme and an immunoglobulin is observed by a minor adaptation of the theoretical treatment to accommodate the fact that thermodynamic activity is monitored on the molal concentration scale because of the constraint of constant pressure that pertains in dynamic light scattering experiments.

The way for improving the efficiency of ammonia and carbon dioxide absorption of choline chloride: Urea mixtures by modifying a choline cation

In the current work, two novel systems formed by chlorides of choline family (ChCl), namely ammonium salts with 2-hydroxyethyl and 2-(2-hydroxyethoxy)ethyl substituents, and urea (U) in a molar ratio 1 : 1 were obtained. Their densities (ρ), viscosities (η), refractive indices (nD) and properties related to the carbon dioxide and ammonia absorption were carefully investigated in a wide temperature range. The solubilities of NH3 and CO2 in the prepared mixtures at T = (303.2–333.2) K and p = (100–639) kPa were measured and linear correlation were used for fitting the experimental data. Based on this, the Henry's law constants both in a molality (Hm) and in a molar fraction scales (Hx), and the changes of enthalpy (ΔsolH∘), Gibbs free energy (ΔsolG∘) and entropy (ΔsolS∘) during the absorption process were calculated. The absorption capacity at 313.2 K and 101 kPa of the mixtures comprising new OH-grafted hydrogen bond acceptors (HBA) were found to be higher by 60 % for NH3 and 17% for CO2 when one methyl in choline cation is exchanged by a 2-hydroxyethyl group, by 103% for NH3 and 27% for CO2 when two methyls are exchanged by two 2-hydroxyethyl groups, by 9% for NH3 and 51% for CO2 when one methyl is exchanged by a 2-(2-hydroxyethoxy)ethyl group, and by 30% for NH3 and 73% for CO2 when two methyls are exchanged by one 2-hydroxyethyl and one 2-(2-hydroxyethoxy)ethyl groups compared to the referent deep eutectic solvent (ChCl : 1.5U). This assumes occurring the ammonia capture via most likely H-bonding interactions between the NH3 molecule(s) and the hydroxyalkyl fragments, while the ether's groups in HBA structure depress the positive effect of latter and hence decrease the general ammonia's solubility in the considered mixtures. In case of carbon dioxide, the absorption capacity of the studied mixtures correlates well with the free volume of the fluid.

Evaluation of the activity coefficients of ternary molecular solutions from osmotic coefficient data

A method is proposed for the evaluation of the activity coefficients of a solution constituted by a solvent (1) and two non-volatile molecular solutes (2,3) from the experimental dependence of the osmotic coefficient of the ternary solution (1,2,3) on composition. A generalized analytical expression is derived to describe such dependence, based on the sum of the weighted contributions of both binary systems and the contribution due to the mixing effect. With the resulting expression and using the solution of the Gibbs-Duhem differential equation for ternary systems, the equations that allows the evaluation of the corresponding experimental activity coefficients of both solutes in ideal dilute solution reference state (molality scale) are derived. From the comparative analysis and discussion of the results obtained for three ternary systems, it was possible to verify that the proposed methodology provides a rigorous alternative to evaluate suitable values ​​of activity coefficients from experimental data of osmotic coefficients. Finally, in order to facilitate the correlation of these values with equations originated in molecular solution modelling (NRTL, UNIQUAC, etc.), the relationships between the corresponding reference states and concentration scales were established.

Third molar surgical difficulty scales: systematic review and preoperative assessment form

Background The main objective of this systematic review was to collect the pre-existing scales for assessing the difficulty of third molar extraction. The secondary objective was to design a proposal for a preoperative evaluation protocol for the difficulty of third molar extraction.Material and Methods Two independent researchers conducted an electronic search in Pubmed (MEDLINE), Cochrane, and Scopus databases during March 2021. Included studies evaluated the prediction of the difficulty of surgical removal of impacted upper or lower third molars using new indices/scales or pre-existing scales with or without modifications. Articles referring to coronectomies or assessing pre-surgical difficulty using other tools were excluded. Neither language nor publication date restrictions were applied.Results Out of 242 articles, 13 prospective cohort studies were finally selected. Seven developed new indices/scales, and 6 assessed the predictive ability of some pre-existing scales. Most of the indices/scales contained radiological variables and few added any patient-related variables. We proposed a preoperative assessment protocol of the difficulty of third molar extraction to facilitate treatment planning and/or considerate referral in cases of high difficulty. This proposal used patient-related, radiological and surgical variables.Conclusions Using a preoperative protocol to evaluate the surgical difficulty, including different patient-specific, radiological and surgical variables, could facilitate treatment planning, help clinicians prevent complications and assess the possibility of referral. Key words:Wisdom teeth, patient characteristics, radiological variables, surgeon experience, assessment form.

Synthesis and properties of symmetric glycerol-derived 1,2,3-triethers and 1,3-diether-2-ketones for CO2 absorption

Five compounds bearing glycerol skeletons: 1,3-diethoxypropan-2-one ([E, K, E]), 2,5,9,12-tetraoxatridecan-7-one ([ME, K, ME]), 1,3-bis(2,2,2-trifluoroethoxy)propan-2-one ([F, K, F]), 7-(2-methoxyethoxy)-2,5,9,12-tetraoxatridecane ([ME, ME, ME]) and 2-(2-methoxyethoxy)-1,3-bis(2,2,2-trifluoroethoxy)propane ([F, ME, F]) – were synthesized from epichlorohydrin at molar scales with high regioselectivity. Density and viscosity were measured over a temperature range of 293.15 to 353.15 K. Henry’s constants for CO2 were obtained under moderate pressures (2 to 10 atm) at 303.15, 318.15, 333.15 and 348.15 K. Comparison of CO2 affinity with dimethyl ethers of polyethylene glycol (DMPEG) and ionic liquids (ILs) indicated that [ME, ME, ME] and [F, ME, F] are excellent candidates as novel physical solvents for CO2 capture. DFT calculations were performed to understand the structure–property-performance relationships for the CO2 absorption mechanism. All five compounds were miscible with most common solvents except hexanes and water. In addition to gas absorption applications, these compounds might also find use as general purpose green solvents.

Alternative formalism for the evaluation of the activity coefficients on ternary electrolyte solutions from osmotic coefficient data

An alternative method is presented, which is independent of any physicochemical model of the electrolyte solution, for the evaluation of the mean ionic activity coefficient in molal scale, γ±i (i: 2,3), of the solutes of a ternary solution (1–2–3), starting from experimental data of the osmotic coefficient on composition ϕexp(m,xi). It is based on the dependence of ln γ±i on ϕ originally derived by H.A.C. McKay and confirmed by S.G. Canagaratna and M. Maheswaran as a particular solution of Gibbs-Duhem equation for multicomponent systems. Its application involves the integration of both ϕ and its derivative ∂ϕ/∂mi, so that it requires a very precise correlation of the dependence ϕexp(m,xi). Therefore, in order to achieve the required precision, the theoretical expression ϕ(m,xi) is developed as the sum of three contributions, (i) ϕDH: the limiting behaviour given by the Debye-Hückel equation for multicomponent systems, (ii) ΔϕDDH: the sum of the deviations to the Debye-Hückel behaviour of the corresponding binary solutions (1–2 and 1–3) and (iii) ΔϕM: a contribution of mixing effect. Finally, introducing the resulting ϕ(m,xi) into the Gibbs-Duhem equation and operating, the corresponding expression of ln γ±i (m,xi) is derived. The capacity of the ϕ(m,xi) equation to correlate the dependence ϕexp(m,xi), the methodology employed to obtain the parameters values, as well as the ln γ±i (m,xi) resulting dependence are illustrated through its application to the analysis of two ternary systems.

Property representations and molecular fragmentation of chemical compounds in QSAR modeling

Basically, molar or weight scales are typical representations of the properties measured for molecular ensembles (substances). This was recently extended by the so called single molecule biology. Here we compare a large property datasets analyzing their relation to the aforementioned representations. The question of the maximal potency of ligands inspired the development and application of ligand efficiency (LE) estimators in drug design. LE could be interpreted as a property representation type. In particular, we compared, LE with boiling points (BP) vs. substance properties typically measured in the weight or molar scales, e.g. the potency, atomic weight percentage, its heavy atom count (HAC) equivalent or market prices of chemicals. As LE was deigned first of all as a measure of binding affinity of a single fragment it refers to a single molecule scale. In turn, BP clearly refers to substances. Despite this difference clear similarities between the trends of LE and BP/MW vs. HAC or MW can be indicated. We have recently showed that a trend of LE vs. heavy atom count (HAC) can be fully understood if we realize the connection of LE with the weight scale. A term 1/MW could be interpreted as an operator connecting the molar and weight scales. In turn 1/MW (1/HAC) fragments a single molecule into the Dalton or HAC fragments. A high correlation to MW or 1/MW was revealed for BOBackspace BP or LE, respectively. In turn, the prices (P) of chemicals charged in $/g are not correlated to 1/MW. A dual meaning of 1/MW (1/HAC) is an origin of uncertainty between molecular fragmentation and scales conversion.

Dissolution thermodynamics and preferential solvation of ketoconazole in some {ethanol (1) + water (2)} mixtures

In this research, the equilibrium mole fraction solubility of ketoconazole in some aqueous-ethanolic mixtures was calculated from previously measured solubility data reported in molarity scale at temperatures from 298.2 to 313.2 K. Experimental mole fraction solubility values were adequately correlated with the Jouyban-Acree and Jouyban-Acree-van't Hoff models. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy of the dissolution processes) were computed using the van't Hoff and Gibbs equations. The enthalpy–entropy relationship for ketoconazole was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition region 0.00 ≤ w1 ≤ 0.20 but positive slope in the region 0.20 ≤ w1 ≤ 0.70. Beyond this composition, the behavior is more complex. Therefore, the driving mechanism for ketoconazole dissolution process is the entropy in water-rich mixtures and the enthalpy in mixtures 0.20 ≤ w1 ≤ 0.70. In addition, the inverse Kirkwood-Buff integrals were used to investigate the preferential solvation of ketoconazole which is preferentially solvated by water molecules in water-rich and also in ethanol-rich mixtures but preferentially solvated by ethanol molecules in mixtures 0.24 ≤ x1 ≤ 0.75. Dissolution thermodynamics and preferential solvation computations were carried out employing whole experimental solubility data points and the simulated data using a minimum number of seven data points as training set, in which there were no significant differences in the obtained numerical values except for enthalpy-entropy compensation data.

Preferential solvation of some corticosteroids in {ethanol (1) + water (2)} mixtures at 298.2 K

The equilibrium solubility of three corticosteroids, namely, budesonide, hydrocortisone and prednisolone in some {ethanol (1) + water (2)} mixtures as expressed in mole fraction at 298.2 K was calculated from reported solubility values expressed in molarity scale. Further, by using the inverse Kirkwood-Buff integrals is observed that these drugs are preferentially solvated by water molecules in water-rich mixtures and apparently also in ethanol-rich mixtures but preferentially solvated by ethanol molecules in mixtures of similar proportions of the solvents.

A study of Eu2O3 solubilization in K2SrCl4 melt at 973 K under the action of CCl4 vapor

A comparative study of carbochlorination processes (treatment with CCl4 vapor in argon flow) of K2SrCl4 melt and K2SrCl4+Eu2O3,solid mixture at 973 K was performed by the potentiometric method with the use of Pt(O2)|ZrO2(Y2O3) membrane oxygen electrode as reversible to oxide ion.Solid Eu2O3 interacts with K2SrCl4 melt that results in partial transformation of the oxide into oxochloride, EuOCl (the degree of Eu2O3 transformation is 0.54) and the process is completely suppressed at oxide ion (SrO) concentration ca. 3∙10−3 mol kg-1; here the melt becomes saturated with respect to both Eu2O3 and EuOCl. The course of interaction of Eu2O3 with K2SrCl4 melt at 973 K obeys the Shchukarev equation.The analysis of van’t Hoff diagrams for these processes showed that the stage of Eu2O3 solubilization under the action of CCl4 is clearly detected. The data corresponding to the finishing of Eu2O3 solubilization in K2SrCl4 melt allowed to estimate the solubility product of Eu2O3 as 1.2·10−22 mol5·kg-5 in molality scale and 3.2·10-26 in mole fractions. The corresponding values for EuOCl are 1.47·10-7 mol3·kg-3 (mCl-= 13.1 mol kg-1) or 1.05·10-9 (mole fractions).An application of the Shreder-Le Chatelier equation for the recalculation of some literature data on the solubilization of rare-earth metal oxides and oxochlorides at different temperatures allowed us to compare them with the results obtained in this work. It was confirmed that the running of the carbochlorination process at low oxide ion concentrations was determined by the rare earth oxide (oxochloride) dissolution similarly to the situation observed in other chloride melts where HCl was used as a chlorinating agent. The literature data and data of this work expressed in units of oxoacidity function Ω and reduced to the same temperature (973 K) are in a good agreement.

Cyanohydridoborate Anions: Synthesis, Salts, and Low-Viscosity Ionic Liquids.

High-yield syntheses up to molar scales for salts of [BH(CN)3 ]- (2) and [BH2 (CN)2 ]- (3) starting from commercially available Na[BH4 ] (Na5), Na[BH3 (CN)] (Na4), BCl3 , (CH3 )3 SiCN, and KCN were developed. Direct conversion of Na5 into K2 was accomplished with (CH3 )3 SiCN and (CH3 )3 SiCl as a catalyst in an autoclave. Alternatively, Na5 is converted into Na[BH{OC(O)R}3 ] (R=alkyl) that is more reactive towards (CH3 )3 SiCN and thus provides an easy access to salts of 2. Some reaction intermediates were identified, for example, Na[BH(CN){OC(O)Et}2 ] (Na7 b) and Na[BH(CN)2 {OC(O)Et}] (Na8 b). A third entry to 2 and 3 uses ether adducts of BHCl2 or BH2 Cl such as the commercial 1,4-dioxane adducts that react with KCN and (CH3 )3 SiCN. Alkali metal salts of 2 and 3 are convenient starting materials for organic salts, especially for low viscosity ionic liquids (ILs). [EMIm]3 has the lowest viscosity and highest conductivity with 10.2 mPa s and 32.6 mS cm-1 at 20 °C known for non-protic ILs. The ILs are thermally, chemically, and electrochemically robust. These properties are crucial for applications in electrochemical devices, for example, dye-sensitized solar cells (Grätzel cells).

Measuring and modelling the absorption and volumetric properties of CO2 and H2S in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate

The absorption capacity of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) for the single gases carbon dioxide and hydrogen sulfide was measured at temperatures from (298 to 353) K and pressures up to about 2.0 MPa. The corresponding molar volumes of CO2/H2S-saturated liquid phase were also measured in the above temperature and pressure ranges. At the same temperature and pressure, the solubility of hydrogen sulfide in [C2mim][BF4], expressed on the molality scale, is more than three times that of CO2. The Henry’s law constants were determined from the new experimental data, which in turn were used to derive the change of some thermodynamic functions for dissolution of the gases in that particular ionic liquid. The partial molar volume at infinite dilution for CO2/H2S + [C2mim][BF4] mixtures was estimated from the measured molar volumes. The new experimental data were correlated by using two models: (a) a model comprised of the extended Henry’s law and Pitzer’s virial expansion for the excess Gibbs energy, and (b) a generic Redlich-Kwong (GRK) type of cubic equation of state. Both models adequately good correlate the experimental data; however, the first model shows a slightly higher correlative accuracy than the second one. The selectivity of [C2mim][BF4] to separate CO2 and H2S is also discussed on the basis of correlation results.

Molecular dynamics simulation of the surface tension of aqueous sodium chloride: from dilute to highly supersaturated solutions and molten salt

Abstract. Sodium chloride (NaCl) is one of the key components of atmospheric aerosols. The surface tension of aqueous NaCl solution (σNaCl,sol) and its concentration dependence are essential to determine the equilibrium water vapor pressure of aqueous NaCl droplets. Supersaturated NaCl solution droplets are observed in laboratory experiments and under atmospheric conditions, but the experimental data for σNaCl,sol are mostly limited up to subsaturated solutions. In this study, the surface tension of aqueous NaCl is investigated by molecular dynamics (MD) simulations and the pressure tensor method from dilute to highly supersaturated solutions. We show that the linear approximation of concentration dependence of σNaCl,sol at molality scale can be extended to the supersaturated NaCl solution until a molality of ∼10.7 mol kg−1 (i.e., solute mass fraction (xNaCl) of ∼0.39). Energetic analyses show that this monotonic increase in surface tension is driven by the increase in excess surface enthalpy (ΔH) as the solution becomes concentrated. After that, the simulated σNaCl,sol remains almost unchanged until xNaCl of ∼0.47 (near the concentration upon efflorescence). The existence of the “inflection point” at xNaCl of ∼0.39 and the stable surface tension of xNaCl between ∼0.39 and ∼0.47 can be attributed to the nearly unchanged excess surface entropy term (T⋅ΔS) and the excess surface enthalpy term (ΔH). After a “second inflection point” at xNaCl of ∼0.47, the simulated σNaCl,sol gradually regains the growing momentum with a tendency to approach the surface tension of molten NaCl (∼175.58 mN m−1 at 298.15 K, MD simulation-based extrapolation). This fast increase in σNaCl,sol at xNaCl>0.47 is a process driven by excess surface enthalpy and excess surface entropy. Our results reveal different regimes of concentration dependence of the surface tension of aqueous NaCl at 298.15 K: a water-dominated regime (xNaCl from 0 to ∼0.39), a transition regime (xNaCl from ∼0.39 to ∼0.47) and a molten NaCl-dominated regime (xNaCl from ∼0.47 to 1).

Complexation of Molybdenum(VI) with GLDA at Different Ionic Strengths

The interaction of the biodegradable ligand, l-glutamic acid N,N-diacetic acid tetrasodium salt (GLDA) with molybdenum(VI) was studied by determining stability constants at pH 6.00, T = 298.15 K, and ionic strength 0.0992 < I/mol·dm−3 < 2.5689 of sodium chloride. The ionic strength dependence of the stability constants was fitted to both extended Debye–Huckel and specific ion interaction models. Job’s method confirmed the formation of one species, MoO3GLDA4−. The values of the stability constants are in agreement with the other data in the literature for the complex formation of aminopolycarboxylic acids with molybdenum(VI). Experimental data were obtained by using UV spectrophotometric method. The formation constant in pure water is 18.96 ± 0.08 on the molal concentration scale.

Temperature dependence of the acid–base and Ca2+-complexation equilibria of d-gluconate in hyperalkaline aqueous solutions

In the current work, the hyperalkaline complexation processes in the Ca2+/d-gluconate (Gluc−) system have been studied under hypersaline conditions (I = 4 M NaCl on the molar and Im = 4.38 mol kg−1 on the molal scale, respectively) and over the temperature range of 25–75 °C by pH potentiometry using H2/Pt electrode and 13C NMR spectroscopy. The potentiometric method was validated at 75 °C. The deprotonation of the alcoholic OH− group(s) of the ligand was also investigated. Finally, the temperature dependence of the stability constants of the mono- and polynuclear complexes forming in the Ca2+/Gluc−/OH− system was determined as well. At this high ionic strength, the formation of anionic complexes seems to be facilitated by ion pair formation.

Solution Thermodynamics and Preferential Solvation of Atenolol in {Ethanol (1) + Water (2)} Cosolvent Mixtures

The solubility of atenolol (ATN) in some {ethanol (1) + water (2)} mixtures expressed in mole fraction at temperatures from 298.2 to 313.2 K was calculated from reported solubility values expressed in molarity scale. The van’t Hoff and Gibbs equations were used to calculate the respective apparent thermodynamic functions: Gibbs energy, enthalpy, and entropy of the dissolution processes. Non-linear enthalpy–entropy relationship was observed for this drug ATN in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition region 0.00 £ w1 £ 0.20 but positive slope in the region 0.20 £ w1 £ 0.40. Beyond this composition, the behavior is more complex. Hence, the driving mechanism for ATN dissolution process is the entropy in water-rich mixtures and the enthalpy in mixtures 0.20 £ w1 £ 0.40. Furthermore, the preferential solvation of ATN by both solvents was analyzed by using the inverse Kirkwood-Buff integrals observing that this drug is preferentially solvated by water molecules in water-rich and also in ethanol-rich mixtures but preferentially solvated by ethanol molecules in mixtures 0.24 £ x1 £ 0.51.

Long-Term Experimental Determination of Solubilities of Micro-Crystalline Nd(III) Hydroxide in High Ionic Strength Solutions: Applications to Nuclear Waste Management

In this study, the experimental results from long-term solubility experiments up to 1146 days on micro-crystalline neodymium hydroxide, Nd(OH)3(micro-cr), in high ionic strength solutions at 298.15 K under well-constrained conditions, are presented. Hydrogen ion concentrations in our experiments are controlled by the dissolution of Nd(OH)3(micro-cr) without artificial adjustment with addition of either an acid or a base, preventing the possibility of phase change that could be induced especially by addition of a base. Such an experimental design also provides the information about the hydrogen ion concentrations buffered by the dissolution of Nd(OH)3, which is currently lacking. The solubility data produced in this work, applicable to geological repositories in high ionic strength environments, are compared with the solubilities of Am(OH)3(s) predicted by using the Waste Isolation Pilot Plant (WIPP) thermodynamic model. The predicted values for Am(OH)3(s) are in good agreement with the experimental values for Nd(OH)3(micro-cr) obtained in this work. Our experimental data indicate that the pHm (negative logarithm of hydrogen ion concentration on a molal scale) buffered by dissolution of Nd(OH)3(micro-cr) ranges from ~ 9.5 to ~ 9.9. As the equilibrium constant for amorphous neodymium hydroxide, Nd(OH)3(am), is useful for several fields, the equilibrium constant regarding the dissolution of Nd(OH)3(am) for the following reaction, $$ {\text{Nd}}\left( {\text{OH}} \right)_{3} \left( {\text{am}} \right) + 3{\text{H}}^{ + } = {\text{Nd}}^{3 + } + 3{\text{H}}_{2} {\text{O}}\left( {\text{l}} \right) $$ is also obtained by evaluating the experimental data in a wide range of ionic strengths from the literature by using the WIPP thermodynamic model. The $$ \log_{10} K_{{{\text{s}}0}}^{0} $$ at 298.15 K for the above reaction obtained in this work is 16.85 ± 0.20 (2σ), which is similar to, but slightly lower than, the values in the literature evaluated in the low ionic strength range. This value can be applied to amorphous americium hydroxide, Am(OH)3(am), using Nd(III) as an analog to Am(III).

An experimental investigation on the solubility of methane in 1-octanol and n-dodecane at ambient temperatures

The synthetic method is used for the determination of the liquid phase solubility of methane in 1-octanol at three temperatures (273.25, 283.15, and 293.2) K and of methane in n-dodecane at 273.1 K at pressures up to about 10 MPa. The new gas solubility data is applied to evaluate the molality scale based Henry's constant of methane in those solvents: (4.31, 4.67, and 4.81 ± 0.05) MPa in 1-octanol and (2.75 ± 0.04) MPa in n-dodecane at the given temperatures, respectively. The experimental technique provides as well the density of the gas-saturated liquid phase and thus allows for evaluation of the partial molar volume of methane at infinite dilution in the solvent: (47, 49, and 49 ± 5) cm3/mol in 1-octanol and (45 ± 5) cm3/mol in n-dodecane, respectively. The experimental results are compared with the limited data from the open literature. At the investigated temperatures, the vapour phase can be treated as pure methane, and the extended Henry's law suffices to accurately correlate the new gas solubility data. However, that vapour-liquid equilibrium model is here expanded allowing to accurately predict the small vapour phase solubility of the solvent in compressed methane which is demonstrated by comparison with experimental data from the literature.