Excess partial molar enthalpies of 2-butoxyethanol and water in 2-butoxyethanol–water mixtures

1989 ◽  
Vol 67 (4) ◽  
pp. 671-676 ◽  
Author(s):  
William Siu ◽  
Yoshikata Koga
Keyword(s):  
Long Range ◽  
Water Clusters ◽  
Pure Water ◽  
Threshold Value ◽  
Water Molecules ◽  
Pure Liquid ◽  
Entire Concentration Range ◽  
Solute Interaction ◽  
Excess Partial Molar Enthalpy ◽  
Partial Molar Enthalpies

Excess partial molar enthalpies of 2-butoxyethanol (BE) and water, [Formula: see text](I = BE or H2O), were measured from 25 to 35 °C in the entire concentration range. The results indicated that there are three concentration regions bounded at about xB = 0.02 and xB = 0.5, xB being the mole fraction of BE. In each region, the concentration and temperature dependence of [Formula: see text] (I = BE or H2O), is distinctively different from those in the other regions, and appears to support the following views: In the water-rich region, xB < 0.02, BE molecules cause an enhancement in the structure of water, and this effect spans a long range via a structurally enhanced network of water. The solute–solute (BE–BE) interaction is repulsive and of a long range character in terms of enthalpy. As xB increases, the repulsive solute–solute interaction becomes stronger sharply to the threshold value, xB ≈ 0.017, whereupon the mode of such mixing no longer becomes possible. In the intermediate range, 0.02 < χB < 0.5, a new scheme whereby BE molecules tend to associate is predominant. Two clathrate-like aggregates of the types h[BE(H2O)k] with k = 55 and 4 may exist together with BE clusters (BE)n In the third region, 0.5 < xB, BE molecules are exactly in the same environment as in pure liquid, while water molecules are almost in the same environment as in pure water. The solution consists of BE and water clusters. Keywords: excess partial molar enthalpy, 2-butoxyethanol–water.

scholarly journals Reactions of H<sup>+</sup>(pyridine)<sub><i>m</i></sub>(H<sub>2</sub>O)<sub><i>n</i></sub> and H<sup>+</sup>(NH<sub>3</sub>)<sub>1</sub>(pyridine)<sub>1</sub>(H<sub>2</sub>O)<sub><i>n</i></sub> with NH<sub>3</sub>: experiments and kinetic modelling under tropospheric conditions

2011 ◽  
Vol 11 (9) ◽  
pp. 24535-24566
Author(s):  
M. J. Ryding ◽  
Å. M. Jonsson ◽  
A. S. Zatula ◽  
P. U. Andersson ◽  
E. Uggerud
Keyword(s):  
Water Clusters ◽  
Kinetic Modelling ◽  
Pure Water ◽  
Ground Level ◽  
Cluster Ions ◽  
Rate Coefficients ◽  
Water Molecules ◽  
Product Ions ◽  
Cluster Ion ◽  
First Time

Abstract. Reactions between pyridine containing water cluster ions, H+(pyridine)1(H2O)n, H+(pyridine)2(H2O)n and H+(NH3)1(pyridine)1(H2O)n (n up to 15) with NH3 have been studied experimentally using a quadrupole time-of-flight mass spectrometer. The product ions in the reaction between H+(pyridine)m(H2O)n and NH3 have been determined for the first time. It is found that the reaction mainly leads to cluster ions of the form HH+(NH3)1(pyridine)1(H2O)n−x, with x = 1 or 2 depending on the initial size of the reacting cluster ion. For a given number of water molecules (from 5 to 15) in the cluster ion, rate coefficients are found to be slightly lower than those for protonated pure water clusters reacting with ammonia. The rate coefficients obtained from this study are used in a kinetic cluster ion model under tropospheric conditions. The results from the model suggest that cluster ions containing ammonia and more than one pyridine, picoline or lutidine molecule should dominate at ground level under typical conditions.

Hydratation und hydrophobe Wechselwirkung der Ionen in Polyelektrolyten mit einer Folgerung bezüglich der biologischen Membranen

1969 ◽  
Vol 24 (4) ◽  
pp. 375-377 ◽  
Author(s):  
G. Zundel ◽  
A. Murr
Keyword(s):  
Sulfonic Acid ◽  
Pure Water ◽  
Water Structure ◽  
Water Molecules ◽  
Pure Liquid ◽  
Ammonium Ions ◽  
Alkali Ions ◽  
Stretching Vibration ◽  
Polystyrene Sulfonic Acid ◽  
Alkyl Ammonium

The OH stretching vibration of the water molecules in membranes of salts of polystyrene sulfonic acid is investigated by IR spectroscopy. In the series of the alkali ions anomalous behaviour of the position of this band is to be seen. If one compares the position of this band with the corresponding one in pure liquid water this anomality is to be understood like follows: From Li⊕ to Cs⊕ in a progressing degree the molecules of water are not still attached between cation and neighboring anions, but they are present as network of „pure“ water structure cross-linked by hydrogen bonds in the neighbourhood of the ions. A similar situation but to an even greater extend is found in the presence of alkyl ammonium ions. These ions are interacting more strongly with the - SO3⊝ ions. The reasons for this are given. By these results it is understandable that in biological membranes the alkyl ammonium group of the lecithins and sphingomyelines - as postulated by FINEAN - are turned away the surface inwardly in the membran. In the end the different hydration behaviour of the Na⊕ and K⊕ ions is discussed.

scholarly journals Reactions of H+(pyridine)m(H2O)n and H+(NH3)1(pyridine)m(H2O)n with NH3: experiments and kinetic modelling

2012 ◽  
Vol 12 (6) ◽  
pp. 2809-2822 ◽  
Author(s):  
M. J. Ryding ◽  
A. S. Zatula ◽  
P. U. Andersson ◽  
E. Uggerud ◽  
Keyword(s):  
Water Clusters ◽  
Kinetic Modelling ◽  
Pure Water ◽  
Ground Level ◽  
Cluster Ions ◽  
Rate Coefficients ◽  
Water Molecules ◽  
Product Ions ◽  
Cluster Ion ◽  
First Time

Abstract. Reactions between pyridine containing water cluster ions, H+(pyridine)1(H2O)n, H+(pyridine)2(H2O)n and H+(NH3)1(pyridine)1(H2O)n (n up to 15) with NH3 have been studied experimentally using a quadrupole time-of-flight mass spectrometer. The product ions in the reaction between H+(pyridine)m(H2O)n (m = 1 to 2) and NH3 have been determined for the first time. It is found that the reaction mainly leads to cluster ions of the form H+(NH3)1(pyridine)m(H2O)n-x, with x = 1 or 2 depending on the initial size of the reacting cluster ion. For a given number of water molecules (from 5 to 15) in the cluster ion, rate coefficients are found to be slightly lower than those for protonated pure water clusters reacting with ammonia. The rate coefficients obtained from this study are used in a kinetic cluster ion model under tropospheric conditions. The disagreement between ambient ground level measurements and previous models are discussed in relation to the results from our model and future experimental directions are suggested.

CONDUCTANCES OF LITHIUM NITRATE SOLUTIONS IN ETHYL ALCOHOL AND ETHYL ALCOHOL - WATER MIXTURES AT 25.0 °C.

1956 ◽  
Vol 34 (9) ◽  
pp. 1232-1242 ◽  
Author(s):  
A. N. Campbell ◽  
G. H. Debus
Keyword(s):  
No Value ◽  
Ethyl Alcohol ◽  
Pure Water ◽  
Lithium Ion ◽  
Water Molecules ◽  
Lithium Nitrate ◽  
Absolute Alcohol ◽  
Pure Alcohol ◽  
Alcohol Water ◽  
Nitrate Solutions

The conductances of solutions of lithium nitrate in 30, 70, and 100 weight per cent ethyl alcohol have been determined at concentrations ranging from 0.01 molar up to saturation, at 25 °C. The densities and viscosities of these solutions have also been determined. The data have been compared with the calculated conductances obtained from the Wishaw–Stokes equation. The agreement is fairly good up to, say, 2 M, for all solvents except absolute alcohol. In the latter solvent there is no value of å, the distance of closest approach, which will give consistent values of the equivalent conductance. In passing from pure water to pure alcohol, the value of å increases progressively and this we attribute to a change in the solvation of the lithium ion from water molecules to alcohol molecules. Some further calculations incline us to the view that the nitrate ion, as well as the lithium ion, is solvated to some extent, at least in alcohol.

scholarly journals Self-Organization of Water Molecules Over 11-Year Solar Cycle

2021 ◽  
Author(s):  
Igor Shevchenko
Keyword(s):  
Solar Activity ◽  
Water Clusters ◽  
The Self ◽  
Self Organization ◽  
Water Molecules ◽  
Annual Variations ◽  
The Earth ◽  
Rate Of Hydrolysis ◽  
Rotation Of The Earth ◽  
Northern And Southern Hemispheres

Abstract The variations of solar activity and distribution of solar energy due to the rotation of the Earth around its axis and around the Sun exert a strong influence on the self-organization of water molecules. As a result, the rate of hydrolytic processes with the participation of water clusters displays diurnal, very large annual variations, and is also modulated by the 11-year cycles of solar activity. It also depends on the geographic latitude and can be different at the same time in the Northern and Southern Hemispheres. This phenomenon is well accounted for by the influence of muons on the self-organization of water molecules. Muons are constantly generated in the upper atmosphere by the solar wind. They reach the surface of the Earth and can penetrate to some depth underground. Buildings also absorb muons. For this reason, the rate of hydrolysis outside and inside buildings, as well as underground, can differ significantly from each other.

scholarly journals Evaluation of Water Indices for Surface Water Extraction in a Landsat 8 Scene of Nepal

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2580 ◽  
Author(s):  
Tri Acharya ◽  
Anoj Subedi ◽  
Dong Lee
Keyword(s):  
Surface Water ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Pure Water ◽  
Confusion Matrix ◽  
Threshold Value ◽  
Environmental Noise ◽  
Water Extraction ◽  
Landsat 8 ◽  
Water Indices

Accurate and frequent updates of surface water have been made possible by remote sensing technology. Index methods are mostly used for surface water estimation which separates the water from the background based on a threshold value. Generally, the threshold is a fixed value, but can be challenging in the case of environmental noise, such as shadow, forest, built-up areas, snow, and clouds. One such challenging scene can be found in Nepal where no such evaluation has been done. Taking that in consideration, this study evaluates the performance of the most widely used water indices: Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Modified NDWI (MNDWI), and Automated Water Extraction Index (AWEI) in a Landsat 8 scene of Nepal. The scene, ranging from 60 m to 8848 m, contains various types of water bodies found in Nepal with different forms of environmental noise. The evaluation was conducted based on measures from a confusion matrix derived using validation points. Comparing visually and quantitatively, not a single method was able to extract surface water in the entire scene with better accuracy. Upon selecting optimum thresholds, the overall accuracy (OA) and kappa coefficient (kappa) was improved, but not satisfactory. NDVI and NDWI showed better results for only pure water pixels, whereas MNDWI and AWEI were unable to reject snow cover and shadows. Combining NDVI with NDWI and AWEI with shadow improved the accuracy but inherited the NDWI and AWEI characteristics. Segmenting the test scene with elevations above and below 665 m, and using NDVI and NDWI for detecting water, resulted in an OA of 0.9638 and kappa of 0.8979. The accuracy can be further improved with a smaller interval of categorical characteristics in one or multiple scenes.

scholarly journals Spectral, Thermal, Crystal Structure, Hirshfeld Surface Analyses and Biological Activities of New Hydrazinium Dipicolinato Copper(II) Tetrahydrate

2019 ◽  
Vol 31 (8) ◽  
pp. 1755-1761
Author(s):  
K. Naresh ◽  
B.N. Sivasankar
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Water Clusters ◽  
Hirshfeld Surface ◽  
Water Molecules ◽  
X Ray ◽  
Biological Studies ◽  
Calf Thymus ◽  
Hydrazinium Cation

A new copper complex of pyridine-2,6-dicarboxylate containing hydrazinium cation, formulated as (N2H5)2[Cu(PDC)2]·4H2O (PDC = pyridine-2,6-dicarboxylate) has been synthesized from copper(II) nitrate, hydrazine hydrate and pyridine-2,6-dicarboxylic acid as a single crystal and characterized by elemental analysis and spectroscopic (IR and UV-visible), thermal (TG/DTG), single crystal X-ray diffraction and biological studies. A six-coordinate complex with a distorted octahedral geometry around Cu(II) ion is proposed and confirmed by X-ray single crystal method. The structure reveals that two pyridine-2,6-dicarboxylate species acting as tridentate ligands and hydrazinium cation present as a counter ion along with non-coordinated four water molecules. The structural units of copper(II) is mutually held by the hydrogen bonds and π···π and C–O···π interactions. The copper(II) complex is connected to one another via O–H···O hydrogen bonds, forming water clusters, which plays an important role in the stabilization of the crystal structure. In the water clusters, the water molecules are trapped by the cooperative association of coordination interactions as well as hydrogen bonds. Both cation and anion interactions and crystal from various types of intermolecular contacts and their importance were explored using Hirshfeld surface analysis. This indicates that O···H/H···O interactions are the superior interactions conforming excessive H-bond in the molecular structure. The interaction of copper(II) complex with calf thymus DNA (CT-DNA) was investigated by electronic absorption spectroscopic technique. The electronic evidence strongly shows that the compound interacts with calf thymus through intercalation with a binding constant of Kb = 5.7 × 104 M–1.

scholarly journals Low-frequency Raman Spectroscopy of Aqueous Solutions of Aliphatic Alcohols

2001 ◽  
Vol 56 (8) ◽  
pp. 529-536 ◽  
Author(s):  
Koji Ydoshida ◽  
Toshio Yamaguchi
Keyword(s):  
Aqueous Solutions ◽  
Raman Spectra ◽  
Mole Fraction ◽  
Water Clusters ◽  
Pure Water ◽  
Low Frequency ◽  
Isosbestic Point ◽  
X Ray Diffraction ◽  
Alcohol Water ◽  
Solvent Clusters

Abstract Low-frequency Raman spectra have been measured at room temperature as functions of the alcohol mole fraction in aqueous solutions of methanol, ethanol, 1-propanol, 2 -propanol, and /er/-butylalcohol (TBA). Intrinsic Raman spectra R (ῡ) were obtained from depolarized Rayleigh wing spectra. Isosbestic points have been observed in R (ῡ) of the aqueous solutions of ethanol, 1-propanol, and 2 -propanol, suggesting that the structure o f the solutions is characterized by individual alcohol aggregates and water clusters without a significant amount of alcohol-water mixed aggregates. The R (ῡ) spectra have been expressed as R (ῡ ,x ) = w R (ῡ ,0 ) + aR(D, 1), where R(ῡ, 0) and R(ῡ, 1) are those for pure water and pure alcohols, respectively, and x is the mole fraction of alcohols. The coefficients w and a show the inflection points at characteristic alcohol mole fractions, where microhetrogeneity and structural transition of the solvent clusters take place, as previously shown by X-ray diffraction. In the aqueous solutions of methanol, where no microhetrogeneity takes place, no clear isosbestic point in R(ῡ) has been observed. For aqueous solutions of TBA, an isosbestic point in R(ῡ) has appeared when xTBA > 0.05. Two inflections points in the coefficients have been observed at xTBA « 0.1 and 0.35; the former composition corresponds to the transition composition from the TBA-TBA intermolecular contact to the TBA water molecular association, as previously reported by neutron diffraction.

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