Fractionation of Hydrogen Isotopes in Aqueous Lithium Chloride Solutions

1988 ◽  
Vol 43 (5) ◽  
pp. 449-453 ◽  
Author(s):  
Masahisa Kakiuchi
Keyword(s):  
Oxygen Isotope ◽  
Isotope Effect ◽  
Lithium Chloride ◽  
Structural Changes ◽  
Platinum Catalyst ◽  
Pure Water ◽  
Free Water ◽  
Hydrogen Gas ◽  
Water Molecules ◽  
Chloride Solutions

The D/H ratio of hydrogen gas in equilibrium with water vapor over aqueous lithium chloride solutions was measured at 25 °C, using a hydrophobic platinum catalyst. Experimental details are described. The hydrogen isotope effect between the solution and pure water depends linearly on the LiCl concentration up to ca. 12 m, and at higher concentrations a marked deviation from linearity takes place, as was also observed for the oxygen isotope effect measured by Bopp et al. On the basis of these hydrogen and oxygen isotope effects it is concluded that H218O is enriched in the water molecules coordinated to Li+ ions and HD16O is enriched in the free water molecules of the solution. The observed deviation from linearity for concentrations higher than ca. 12m is interpreted in terms of structural changes in the hydration sphere of the Li+ ions.

Hydrogen Isotope Fractionation in Aqueous Alkaline Earth Chloride Solutions

2007 ◽  
Vol 62 (12) ◽  
pp. 721-728 ◽  
Author(s):  
Masahisa Kakiuchi
Keyword(s):  
Isotope Effect ◽  
Hydrogen Isotope ◽  
Alkaline Earth ◽  
Platinum Catalyst ◽  
Pure Water ◽  
Pressure Ratio ◽  
Hydrogen Gas ◽  
Chloride Solutions ◽  
Aqueous Chloride ◽  
Hydrogen Isotope Effect

The D/H ratio of hydrogen gas in equilibrium with aqueous alkaline earth (Mg, Ca, Sr or Ba) chloride solutions measured at 25◦C using a hydrophobic platinum catalyst, was found to be higher than the D/H ratio equilibrated with the applied pure water. The hydrogen isotope effect between such solutions and pure water changes with the molality of the solutions. The order of the D/H ratios in alkaline earth chlorides is found to be BaCl2 > SrCl2 ≥ CaCl2 ≥ MgCl2. The hydrogen isotope effect in the aqueous chloride solutions of Mg, Ca, Sr or Ba ions is significantly larger than that in the aqueous chloride solutions of Li, Na, K or Cs ions. For MgCl2 and CaCl2 solutions, the hydrogen isotope effect is opposite to the oxygen isotope effect. The results are compared with the free energy change of transfer from H2O to D2O, and are discussed for the vapour pressure ratio of H2O and D2O of CaCl2 solutions.

Hydrogen Isotope Fractionation in Aqueous Alkali Halide Solutions

1997 ◽  
Vol 52 (11) ◽  
pp. 811-820 ◽  
Author(s):  
Masahisa Kakiuchi
Keyword(s):  
Oxygen Isotope ◽  
Isotope Effect ◽  
Alkali Halide ◽  
Hydrogen Isotope ◽  
Isotope Fractionation ◽  
Free Water ◽  
Aqueous Alkali ◽  
Water Molecules ◽  
Oxygen Isotope Fractionation ◽  
Hydrogen Isotope Effect

Abstract The D/H ratios of hydrogen gas in equilibrium with aqueous alkali halide solutions were deter-mined at 25 °C, using a hydrophobic platinum catalyst. The hydrogen isotope effect between the solution and pure water changes linearly with the molality of the solution at low concentrations, but deviates from this linearity at higher concentration for all alkali halide solutions. The magnitude of the hydrogen isotope effect is in the order; Kl > Nal > KBr > CsCl ≧ NaBr > KCl > NaCl > LiCl, at concentrations up to a molality of 4 m. The sign and trend of the hydrogen isotope effect is different from that of oxygen. In aqueous alkali halide solutions, the hydrogen isotope effect is influenced by both the cation and the anion species, while the oxygen isotope effect is mainly caused by the cation species. This suggests that the mechanism of hydrogen isotope fractionation between the water molecules in the hydration spheres and the free water molecules differs from the mechanism of the oxygen isotope fractionation. The hydrogen and oxygen isotope effects for alkali halides, except LiCl and NaCl, may be influenced by changes in energy of the hydrogen bonding in free water molecules.

Kinetics of the hydrolysis of thiochloroformate esters in pure water

1970 ◽  
Vol 48 (4) ◽  
pp. 522-527 ◽  
Author(s):  
A. Queen ◽  
T. A. Nour ◽  
M. N. Paddon-Row ◽  
K. Preston
Keyword(s):  
Isotope Effect ◽  
Structural Changes ◽  
Pure Water ◽  
Activation Parameters ◽  
Deuterium Isotope Effect ◽  
Hydro Carbon ◽  
Electron Donation ◽  
Kinetics Of ◽  
Hydrolysis Of

The effects of structural changes on the rates of hydrolysis of a series of thiochloroformate esters in water have been investigated. The reactivity is enhanced by increased electron donation by the hydro carbon group. These results, the activation parameters for the hydrolysis of methyl thiochloroformate and the solvent deuterium isotope effect, are shown to be consistent with the operation of the SN1 mechanism.

scholarly journals Homeopathic Potencies vary from each other with respect to relative proportions of free and bound water molecules

2021 ◽  
Vol 13 (47) ◽  
pp. 121-121
Author(s):  
Nirmal Chandra Sukul ◽  
Indrani Chakraborty ◽  
Soumita Datta ◽  
Anirban Sukul
Keyword(s):  
Absorption Spectra ◽  
Ethanol Concentration ◽  
Pure Water ◽  
Molar Fraction ◽  
Free Water ◽  
Difference Spectrum ◽  
Ftir Spectra ◽  
Water Molecules ◽  
Drug Molecules ◽  
The Difference

ABSTRACT Homeopathic potencies 12CH and above cross the Avogadro number, and as such do not contain any original drug molecules in their aqueous ethanol medium. It is thought H-bonded water structures preserved by ethanol carry the information of initial drug molecules. Potentized drugs show some differences with respect to their infrared (IR) absorption spectra. In a water-ethanol solution, free water molecules vary according the concentration of ethanol. In the present study the concentration of ethanol has been kept constant at 0.03 molar fraction in 6 different homeopathic potencies. To see whether different homeopathic potencies having fixed ethanol content show variation in free water molecules. Two potencies like 8CH and 32CH of three homeopathic drugs Natrum mur, Cantharis and Nux vomica were used in the study, and their ethanol concentration was kept fixed at 0.03 molar fraction. The control was considered to be aquous ethanol at the same concentration. Spectrum of pure water was also taken. Fourier transform infrared (FTIR) absorption spectra were obtained in the wave number region of 4000 – 2800 cm-1. The half-width at half-maximum was measured for each spectrum. The intensity of each spectrum was normalized at 3410 cm-1 close to the peak. The difference spectrum (absorbance of drug solution – absorbance of pure water) for each drug and the control was obtained. FTIR spectra showed variation in absorbance intensity on both the high and low frequency side of the O-H stretching band in different drugs as well as the control. The C-H stretching band of 2977 cm-1 also showed variation in intensity in different drugs. In the difference spectra the absorbance intensity at the dip at 3630 cm-1 varied in different drugs and the control. The decrease in intensity at 3630 cm-1 and subsequent rise in intensity at lower frequency region represent the level of free water molecules and strong alcoholic O-H band around 3250 cm-1, respectively. The drug and the control solutions show distinct variation in their FTIR spectra. The drugs have different levels of bound and free water molecules although their ethanol concentration is same. Keywords-Homeopathic potencies, FTIR spectra, free water molecules, intensity and difference spectrum.

scholarly journals Water Activity

2012 ◽  
Vol 27 ◽  
pp. 565-569 ◽  
Author(s):  
O. F. Nielsen ◽  
M. Bilde ◽  
M. Frosch
Keyword(s):  
Surface Tension ◽  
Vapor Pressure ◽  
Aqueous Solutions ◽  
Vapour Pressure ◽  
Pure Water ◽  
Free Water ◽  
Water Molecules ◽  
Pressure Measurements ◽  
Metabolic Activities ◽  
Vapor Pressure Measurements

Microorganisms require water for their metabolic activities. Only a fraction of water in foodstuffs, the so-called free water, is available for this purpose. The amounts of free water previously estimated by two different methods (Frosch et al. (2010), Frosch et al. (2011), and Low (1969)) are compared for aqueous solutions of four electrolytes, NaCl, NH4Cl, Na2SO4, (NH4)2SO4: (i) vapour pressure measurements of the solutions relative to that of pure water (water activities) and (ii) low-wavenumber Raman spectra in the R(ν)-representation. For each electrolyte deviations were found between results from the two methods. All water molecules in the illuminated volume contribute to the Raman data. The vapor pressure measurements refer to water molecules at the water/atmosphere interface where surface tension is important. Differences in surface tension for the four electrolytes qualitatively explain deviations between the amounts of “free water” observed by the two methods.

Calculations of the Oxygen Isotope Fractionation between Hydration Water of Cations and Free Water

1974 ◽  
Vol 29 (11) ◽  
pp. 1608-1613 ◽  
Author(s):  
P. Bopp ◽  
K. Heinzinger ◽  
P. C. Vogel
Keyword(s):  
Water Molecule ◽  
Oxygen Isotope ◽  
Gas Phase ◽  
Isotope Fractionation ◽  
Pure Water ◽  
Free Water ◽  
Oxygen Isotope Fractionation ◽  
Free Water Molecule ◽  
Separation Factors ◽  
Fractionation Factors

The oxygen isotope fractionation factors between the hydration complex of the alkali ions in the gas phase and a free water molecule have been computed on the basis of the energy surfaces calculated by Kistenmacher, Popkie and Clementi for a water molecule in the field of an alkali ion. For comparison with recently measured oxygen isotope fractionation factors in aqueous alkali halide solutions, the gas phase values are multiplied with the corresponding separation factors between water vapor and liquid water thus relating the hydration complex in the gas phase with pure water. Qualitative agreement between computed and observed fractionation factors has been found for H2O and D2O even neglecting the isotope effect connected with the transfer of the hydration complex from the gas phase to the solution. This transfer effect is estimated for H2O by a quantitative comparison of computed and observed oxygen isotope fractionation factors.

Temperature and concentration dependence of equivalent conductivity in Ca(NO3)2-CaI2-H2O system

1980 ◽  
Vol 45 (6) ◽  
pp. 1639-1645 ◽  
Author(s):  
Jindřich Novák ◽  
Ivo Sláma
Keyword(s):  
Linear Function ◽  
Concentration Dependence ◽  
Mole Fraction ◽  
Constant Temperature ◽  
Salt Concentration ◽  
Free Water ◽  
Water Molecules ◽  
Equivalent Conductivity ◽  
Calcium Salts ◽  
Fraction I

The dependence of the equivalent conductivity on the temperature and composition of the Ca(NO3)2-CaI2-H2O system was studied. The ionic fraction [I-]/([I-] + [NO-3]) was changed from 0.1 to 0.5, the mole fraction of calcium salts (assumed in anhydrous form in the presence of free water molecules) was 0.075-0.200. The equivalent conductivity was found to be a linear function of the ionic fraction at constant temperature and salt concentration.

Site-selective oxygen isotope effect in optimally doped YBa2Cu3O6 + x

Nature ◽  
1994 ◽  
Vol 371 (6499) ◽  
pp. 681-683 ◽  
Author(s):  
D. Zech ◽  
H. Keller ◽  
K. Conder ◽  
E. Kaldis ◽  
E. Liarokapis ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Effect ◽  
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