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41.
在所有电极过程中研究最多的是析氢反应,其重要性一直为化学界所关注。提高电极活性的各种方法中,普遍采用电沉积法,它价廉简便、效果明显。但涂层不够牢固,在使用过程中易脱落,使用寿命短。为了克服上述缺点,作者将电沉积和离子注入技术联合使用,即在Ni、W镀层上注入Mo离子,利用Mo离子的能量将Ni、W打入表面内层,进行离子束混合。这既 相似文献
42.
Christoph Luef Aloke Paul Jiri Vizdal Ales Kroupa Alexander Kodentsov Herbert Ipser 《Monatshefte für Chemie / Chemical Monthly》2006,137(4):381-395
Summary. The partial and integral enthalpies of mixing of liquid Bi–Sn–Zn alloys were determined at 500°C by a drop calorimetric technique
using a Calvet-type microcalorimeter. The ternary interaction parameters in the Bi–Sn–Zn system were fitted using the Redlich-Kister-Muggianu model for substitutional solutions, and isoenthalpy curves of the integral molar enthalpy of mixing at 500°C were constructed.
Furthermore, a DSC technique was used to determine the liquidus temperatures in three sections (3, 5, and 7 at.% Zn) as well
as the invariant reaction temperature of the ternary eutectic L ⇄ (Bi) + (Sn) + (Zn). The ternary eutectic reaction was found
at 135°C. 相似文献
43.
The ion product of water and the dissociation constants of carbonic acid have been determined in 0.1, 1.0, 3.0, and 5.0M NaClO4 at 25°C. The ion product of water K
w
'
has been evaluated by emf measurements with a combined glass electrode in NaClO4 solutions containing 0.001–0.1M HCLO4 or NaOH. The product K
H
'
K
l
'
K
2
'
of the Henry constant for CO2 and the dissociation constants for H2CO3 have been determined by titration of carbonate solutions equilibrated with pCO2 =10–3.52 atm, and K
2
'
has been evaluated by potentiometric titration and by measuring the H+ concentration at fixed HCO
3
–
and CO
3
2-
concentrations. The ion interaction (Pitzer) equations are applied to describe the constants K
w
'
, K
2
'
and K
H
'
H
1
'
K
2
'
as a function of the NaClO4 concentration. The experimental data are used to evaluate the mixing parameters
i/ClO
4 and
i/ClO
4
-/Na+ fori = OH
-,HCO
3
-
andCO
3
2- 相似文献
44.
M. Nagy 《Colloid and polymer science》1985,263(3):245-265
45.
C. Christov S. Petrenko C. Balarew V. Valyashko 《Monatshefte für Chemie / Chemical Monthly》1994,125(12):1371-1382
Summary The standard method ofPitzer for predicting the solubility isotherms of systems in which solid phases with a constant composition crystallize is applied to cases when mixed crystals are formed. The four-component carnallite type systems RbCl-CsCl-MgCl2-H2O, RbCl-KCl-MgCl2-H2O, and RbCl-RbBr-MgCl2-MgBr2-H2O and the corresponding subsystems are thermodynamically simulated at 25°C. It is established that the solubility diagrams consist of crystallization regions of the simple saltsMX,MX, MgX
2·6H2O, and MgX2·6H2O and of the corresponding carnallite type double salts with the composition 1:1:6. A method of calculation of the integralGibbs energy of mixingG
mix(s) of crystals formed in water-salt systems has been proposed. The results on the systems RbCl-KCl-H2O, RbCl-RbBr-H2O, and MgCl2-MgBr2-H2O are compared with experimental data from the literature and with values calculated using various models.
Thermodynamische Simulation von Vierkomponentensystemen des Carnallit-Types
Zusammenfassung DiePitzer-Methode zur Voraussage der Löslichkeitsisothermen in Mehrstoffsystemen, in welchen feste Phasen mit konstanter Zusammensetzung auskristallisieren, wurde auch für Fälle angewendet, bei denen sich Mischkristalle bilden. Die Vierstoffsysteme RbCl-CsCl-MgCl2-H2O, RbCl-KCl-MgCl2-H2O und RbCl-RbBr-MgCl2-MgBr2-H2O, aus welchen Carnallit-Typ-Mischkristalle auskristallisieren, und die dazugehörigen Dreistoff-Randsysteme wurden bei 25°C simuliert. Man stellt fest, daß die Löslichkeitsdiagramme sowohl Kristallisationsbereiche der einfachen SalzeMX,M'X, MgX 2·6H2O und MgX 2·6H2O als auch der entsprechenden carnallitartigen Doppelsalze mit der Zuzammensetzung 1:1:6 umfassen. Eine Methode zur Berechnung derGibbs-EnergieG mix(s) für die in Wasser-Salz-Systemen gebildeten Mischkristalle wird vorgeschlagen. Die für die Systeme RbCl-KCl-H2O, RbCl-RbBr-H2O und MgCl2-MgBr2-H2O erhaltenen Ergebnisse werden mit experimentellen Literaturdaten und Resultaten von Berechnungen aufgrund verschiedener Modelle verglichen.相似文献
46.
T. de Beer G. Ph. Hoornweg G. J. Grootendorst N. H. Velthorst C. Gooijer 《Analytica chimica acta》1996,330(2-3):189-197
An explorative study on the compatibility of liquid separation systems, such as (micro) liquid chromatography (LC) and capillary electrophoresis (CE), and forward-scattering degenerate four-wave mixing (F-D4WM) as a detection method is presented. F-D4WM is a laser-based technique showing some analogy with holographic spectroscopy: a signal on a theoretical dark background is observed as a result of light absorption by an analyte. Parameters considered are solvent composition focussing on acetonitrile, methanol and water; mobile phases in LC and CE), detector cell construction, and influences of laser beam powers. A specially designed detector cell has been developed to meet the Brewster condition, both at the air-quartz and the quartz-liquid boundaries. For practical reasons, the tested cell has an optical pathlength of 1 mm; reduction to 100 μm is required to apply the cell in microseparations. The F-D4WM technique has been involved for detection in a conventional-size, reversed-phase LC separation of 1- and 2-aminoanthraquinones. The detection limit obtained (for the 1 mm cell) is 2 × 10−5 absorbance units. The experiments indicate that further reduction of background deserves explicit attention. 相似文献
47.
稳态双曲流场中液/液混合的粘性液滴哑铃分散模型 总被引:1,自引:0,他引:1
通过对稳态双曲流场中液/液混合体系分散相液滴所受分散作用力的分析,建立了粘性液滴的哑铃分散模型.趋于将两粘性液滴分开的分散作用力与粘度比、流场类型和强度、液滴半径、哑铃取向和尺寸有关.该模型解释了流场类型与分散作用的关系.流场类型对液滴的分散具有很大影响,在纯应变拉伸流场中分散作用力是简单剪切流场中的两倍,因而对于液滴的分散,拉伸流场较简单剪切流场更有效,这与以前的实验结论符合.当体系粘度比趋于无穷大时本模型转化为刚性哑铃分散模型 相似文献
48.
The excess Gibb's free energy of mixing, GE, for ethyl iodide+toluene at 25°C have been obtained from the measured vapor pressuure data. The HE and GE values for ethyl iodide+toluene are positive throughout the ethyl iodide concentration range and GE>HE. The results have been analyzed in terms of Flory and ideal associated model theory of nonelectrolyte solutions. It has been observed that the ideal associated model approach which assumes the presence of AN and A2B molecular species describes well (within±10 J-mol–1 in the worst case) the general dependence of HE on XA (mole fraction of ethyl iodide) over the whole composition range for ethyl iodide+toluene mixtures. The equilibrium constants for A+A AB and 2A+BA2B reactions along with the enthalpies of formation of AB and A2B molecular species have been calculated. 相似文献
49.
The enthalpy change on mixing solutions of methyl-substituted benzenesulfonic acids and their salts, with salts having a common
cation or anion, at constant ionic strength in mixtures of 1,4-dioxane with water, were measured at 25°C. The heat effects
of mixing solutions having a common anion increase almost linearly with the reciprocal value of the dielectric constant of
the solvent. The heat effects of mixing solutions having a common cation, which are all negative in water-rich solutions,
become endothermic after a certain value of the dielectric constant is passed. The results are discussed in terms of the solute-solvent
structural properties.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
50.
Five of the six possible aqueous two-salt mixtures from among NaCl, KCl, NaH2PO4,and KH2PO4 have been studied by the isopiestic method at 25°C. The sixth mixture, NaCl–KCl, has been studied previously. The deviations from ideal mixing behavior are described by a series of coefficients which were found by regression analysis. The coefficients were used to calculate the excess Gibbs energies of mixing for equal ionic strength fractions of each salt and the trace activity coefficient of each salt at an ionic strength of 2 mode-kg–1. The cross-square mixing rule is obeyed within experimental uncertainty for the excess Gibbs energies of mixing. 相似文献