Hydration of the potassium ion in the gas phase: enthalpies and entropies of hydration reactions

1969 ◽  
Vol 47 (14) ◽  
pp. 2619-2627 ◽  
Author(s):  
S. K. Searles ◽  
P. Kebarle
Keyword(s):  
Water Vapor ◽  
Gas Phase ◽  
Thermionic Emission ◽  
Reaction Chamber ◽  
Experimental Result ◽  
Electrostatic Model ◽  
Model Calculations ◽  
Thermodynamic Constants ◽  
Electrostatic Calculations ◽  
Good Agreement

The thermodynamic constants ΔH0n−1,n, ΔG0n−1,n, and ΔS0n−1,n for the reaction [n − 1, n]: K+(H2O)n−1 + H2O = K+(H2O)n proceeding in the gas phase were measured for n = 1 to n = 6. The equilibria were studied in a reaction chamber containing water vapor at pressures from 0.3 to 6 Torr and at temperatures from −11 to 390 °C. The potassium ions were produced by thermionic emission in a filament chamber and then were equilibrated with the water vapor in the reaction chamber. The relative ionic concentrations were detected with a mass spectrometer. The experimental ΔH0n−1,n values are compared with potential energy differences for the reactions [n − 1, n] based on simple electrostatic model calculations. The electrostatic calculations produce values in fair agreement with the experimental results. The ΔS00,1 calculated on basis of statistical mechanics and energies obtained with the electrostatic model is in very good agreement with the experimental result.

Gas/Aerosol Chemical Reactions in the NaOH-SO2-H2O System

1996 ◽  
Vol 50 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Christopher L. Aardahl ◽  
E. James Davis
Keyword(s):  
Water Vapor ◽  
Light Scattering ◽  
Gas Phase ◽  
Raman Spectra ◽  
Chemical Reactions ◽  
Reaction Chamber ◽  
Raman Light Scattering ◽  
Naoh Solution ◽  
Solution Droplet ◽  
Hydrolysis Of

The hydrolysis of a solid NaOH microparticle in humid nitrogen and the chemical reaction between the resulting NaOH solution microdroplet and SO2 gas have been studied with the use of elastic and inelastic (Raman) light scattering. A single solid NaOH particle was levitated electrodynamically in a reaction chamber and exposed to water vapor. After hydrolysis/deliquescence, the resulting solution droplet was exposed to SO2 gas. Raman spectra and elastic resonance spectra collected during the reactions indicate that low SO2 concentrations in the gas phase yield NaHSO3 while high SO2 concentrations result in Na2SO3 as the product. These results indicate that the reversibility of the key reactions becomes important when the SO2 concentration is low.

scholarly journals Influence of spin polarizability on liquid gas phase transition in the nuclear matter

2015 ◽  
Vol 24 (10) ◽  
pp. 1550075 ◽  
Author(s):  
Z. Rezaei ◽  
M. Bigdeli ◽  
G. H. Bordbar
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Gas Phase ◽  
Energy Equation ◽  
Experimental Result ◽  
Critical Properties ◽  
Spin Polarizability ◽  
Spin Polarized ◽  
Good Agreement ◽  
Second Order Phase Transition

In this paper, we investigate the liquid gas phase transition for the spin polarized nuclear matter. Applying the lowest order constrained variational (LOCV) method, and using two microscopic potentials, AV18 and UV14+TNI, we calculate the free energy, equation of state (EOS), order parameter, entropy, heat capacity and compressibility to derive the critical properties of spin polarized nuclear matter. Our results indicate that for the spin polarized nuclear matter, the second-order phase transition takes place at lower temperatures with respect to the unpolarized one. It is also shown that the critical temperature of our spin polarized nuclear matter with a specific value of spin polarization parameter is in good agreement with the experimental result.

Enhanced Photoyield with Decreasing Film Thickness on Metal-Semiconductor Structures

1996 ◽  
Vol 448 ◽  
Author(s):  
V. Hoffmann ◽  
M. Brauer ◽  
M. Schmidt
Keyword(s):  
Quantum Yield ◽  
Film Thickness ◽  
Layer Thickness ◽  
Experimental Results ◽  
Experimental Result ◽  
Model Calculations ◽  
Hot Carrier ◽  
Semiconductor Structures ◽  
Carrier Scattering ◽  
Good Agreement

AbstractExperimental results of the internal quantum yield Yi associated with the internal photoemission on Au/n-Si structures are presented. The samples were prepared on Si(100) and Si(111) substrates with photoemitter layer thicknesses ranging from 5 nm to 50 nm. The Yi was measured at temperatures between 165 K and 300 K with the photoexciting energy varying from 0.72 eV to 1.07 eV. It was found that the Yi increases with decreasing Au layer thickness with a strong enhancement (40 times) in regard to the conventional Fowler theory. This experimental result is in good agreement with model calculations taking account of hot carrier scattering in the photoemitter layer. Barrier energies are larger than deduced from the Fowler plot.

COMPUTER MODELING OF CHEMICAL EQUILIBRIUMS IN WO3–H2O SYSTEM

2017 ◽  
pp. 35-48 ◽  
Author(s):  
V.P. Bondarenko ◽  
O.O. Matviichuk
Keyword(s):  
Transition Temperature ◽  
Gas Phase ◽  
Single Phase ◽  
Reference Data ◽  
Maximum Amount ◽  
Reaction Products ◽  
Influence Of Temperature ◽  
Equilibrium Chemical ◽  
Program Data ◽  
Good Agreement

Detail investigation of equilibrium chemical reactions in WO3–H2O system using computer program FacktSage with the aim to establish influence of temperature and quantity of water on formation of compounds of H2WO4 and WO2(OH)2 as well as concomitant them compounds, evaporation products, decomposition and dissociation, that are contained in the program data base were carried out. Calculations in the temperature range from 100 to 3000 °С were carried out. The amount moles of water added to 1 mole of WO3 was varied from 0 to 27. It is found that the obtained data by the melting and evaporation temperatures of single-phase WO3 are in good agreement with the reference data and provide additionally detailed information on the composition of the gas phase. It was shown that under heating of 1 mole single-phase WO3 up to 3000 °С the predominant oxide that exist in gaseous phase is (WO3)2. Reactions of it formation from other oxides ((WO3)3 and (WO3)4) were proposed. It was established that compound H2WO4 is stable and it is decomposed on WO3 and H2O under 121 °C. Tungsten Oxide Hydrate WO2(OH)2 first appears under 400 °С and exists up to 3000 °С. Increasing quantity of Н2О in system leads to decreasing transition temperature of WO3 into both liquid and gaseous phases. It was established that adding to 1 mole WO3 26 mole H2O maximum amount (0,9044–0,9171 mole) WO2(OH)2 under temperatures 1400–1600 °С can be obtained, wherein the melting stage of WO3 is omitted. Obtained data also allowed to state that that from 121 till 400 °С WO3–Н2O the section in the О–W–H ternary system is partially quasi-binary because under these temperatures in the system only WO3 and Н2O are present. Under higher temperatures WO3–Н2O section becomes not quasi-binary since in the reaction products WO3 with Н2O except WO3 and Н2O, there are significant amounts of WO2(OH)2, (WO3)2, (WO3)3, (WO3)4 and a small amount of atoms and other compounds. Bibl. 12, Fig. 6, Tab. 5.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

Explaining the magnetism of gold

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Formation Enthalpy ◽  
Gold Atom ◽  
Orbital Energy ◽  
Knudsen Effusion ◽  
Energy Diagram ◽  
Unpaired Electrons ◽  
The Difference ◽  
Good Agreement

<p>In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au<sub>2</sub> (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au<sub>2</sub>, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au<sub>2</sub> with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol<sup>-1</sup>), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol<sup>-1</sup> to the Au-Au bond<sup>7</sup>. So, as expected, in the specie with none unpaired electrons, the two 6s<sup>1</sup> (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au<sub>2</sub> with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au<sub>2</sub> is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).</p>

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

scholarly journals Upcycling of Vine Shoots: Production of Fillers for PHBV-Based Biocomposite Applications

2020 ◽  
Author(s):  
Grégoire David ◽  
Laurent Heux ◽  
Stéphanie Pradeau ◽  
Nathalie Gontard ◽  
Hélène Angellier-Coussy
Keyword(s):  
Water Vapor ◽  
Gas Phase ◽  
Mechanical Performance ◽  
Low Cost ◽  
Water Vapor Permeability ◽  
Contact Angles ◽  
Vapor Permeability ◽  
Water Contact ◽  
Median Diameter ◽  
Cost Of Materials

Abstract This paper aims at investigating the potential of vine shoots (ViSh) upcycling as fillers in novel poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV) based biocomposites. ViSh particles of around 50 µm (apparent median diameter) were obtained combining dry grinding processes, and mixed with PHBV using melt extrusion. Thermal stability and elongation at break of biocomposites were reduced with increasing contents of ViSh particles (10, 20 and 30 wt%), while Young’s modulus and water vapor permeability were increased. It was shown that a surface gas-phase esterification allowed to significantly increase the hydrophobicity of ViSh particles (increase of water contact angles from 59° to 114°), leading to a reduction of 27% in the water vapor permeability of the biocomposite filled with 30 wt% of ViSh. The overall mechanical performance was not impacted by gas-phase esterification, demonstrating that the interfacial adhesion between the virgin ViSh particles and the PHBV matrix was already good and that such filler surface treatment was not required in that case. It was concluded that ViSh particles can be interestingly used as low cost fillers in PHBV-based biocomposites to decrease the overall cost of materials.

DIELECTRIC CONSTANT AND SEEBECK COEFFICIENT FOR SEMICONDUCTORS: THERMODYNAMIC AND DFT STUDIES

2013 ◽  
Vol 12 (06) ◽  
pp. 1350057 ◽  
Author(s):  
HSIU-YA TASI ◽  
CHAOYUAN ZHU
Keyword(s):  
Boundary Condition ◽  
Dielectric Constant ◽  
Seebeck Coefficient ◽  
Gas Phase ◽  
Present Method ◽  
Dielectric Constants ◽  
Semiconductor Materials ◽  
Electronic Polarizability ◽  
Seebeck Coefficients ◽  
Good Agreement

Dielectric constants and Seebeck coefficients for semiconductor materials are studied by thermodynamic method plus ab initio quantum density functional theory (DFT). A single molecule which is formed in semiconductor material is treated in gas phase with molecular boundary condition and then electronic polarizability is directly calculated through Mulliken and atomic polar tensor (APT) density charges in the presence of the external electric field. This electronic polarizability can be converted to dielectric constant for solid material through the Clausius–Mossotti formula. Seebeck coefficient is first simulated in gas phase by thermodynamic method and then its value divided by its dielectric constant is regarded as Seebeck coefficient for solid materials. Furthermore, unit cell of semiconductor material is calculated with periodic boundary condition and its solid structure properties such as lattice constant and band gap are obtained. In this way, proper DFT function and basis set are selected to simulate electronic polarizability directly and Seebeck coefficient through chemical potential. Three semiconductor materials Mg 2 Si , β- FeSi 2 and SiGe are extensively tested by DFT method with B3LYP, BLYP and M05 functionals, and dielectric constants simulated by the present method are in good agreement with experimental values. Seebeck coefficients simulated by the present method are in reasonable good agreement with experiments and temperature dependence of Seebeck coefficients basically follows experimental results as well. The present method works much better than the conventional energy band structure theory for Seebeck coefficients of three semiconductors mentioned above. Simulation with periodic boundary condition can be generalized directly to treat with doped semiconductor in near future.

THEORETICAL CALCULATION OF pKb VALUES FOR ANILINES AND SULFONAMIDE DRUGS IN AQUEOUS SOLUTION

2012 ◽  
Vol 11 (02) ◽  
pp. 283-295 ◽  
Author(s):  
BAHRAM GHALAMI-CHOOBAR ◽  
ALI GHIAMI-SHOMAMI ◽  
PARIA NIKPARSA
Keyword(s):  
Gas Phase ◽  
Continuum Model ◽  
Correlation Equation ◽  
Polarizable Continuum Model ◽  
Free Energies ◽  
Pcm Model ◽  
Solvation Models ◽  
Polarizable Continuum ◽  
Better Than ◽  
Good Agreement

In this work, calculations of p K b values have been performed for aniline and its substituted derivatives and sulfonamide drugs by using Gaussian 98 software package. Gas-phase energies were calculated with HF /6-31 G ** and B3LYP /6-31 G ** levels of theory. Free energies of solvation have been computed using the polarizable continuum model (PCM), conductor-like polarizable continuum model (CPCM) and the integral equation formalism-polarizable continuum model (IEFPCM) at the same levels which have been used for geometry determination in the gas-phase. The results show that the calculated p K b values using the B3LYP /6-31 G ** are better than those using the corresponding HF /6-31 G **. At first, the correlation equation was found to determine the p K b values of the investigated anilines. Then, this correlation equation was used to calculate the p K b values of the sulfonamide drugs. The results obtained indicate that the PCM model is a suitable solvation model for calculating p K b values in comparison to the other solvation models. For the investigated compounds a good agreement between the experimental and the calculated p K b values was also observed.

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