共查询到20条相似文献,搜索用时 46 毫秒
1.
E. A. Masimov B. G. Pashayev H. Sh. Hasanov S. I. Musayeva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(12):2105-2107
The dynamic viscosity and density of a water-polyethylene glycol-KOH system are measured at temperatures of 293.15 to 323.15 K in concentrations ranging from 0.00001 and 0.001 (mole fractions). The activation parameters of viscous flow (ΔG η ≠ , ΔH η ≠ , and ΔS η ≠ ), structural temperature (T 0), the partial molar volume of polyethylene glycol (PEG) in solution $\left( {\tilde V} \right)$ , intrinsic viscosity([η]), and the Huggins constant (K H), are calculated. It is found that PEG has a structuring effect on water in water-PEG and water-PEG-KOH systems, with the PEG structuring effect in the latter being somewhat attenuated by the destructuring influence of KOH. 相似文献
2.
V. Jedináková Z. Dvořák J. Žilková 《Journal of Radioanalytical and Nuclear Chemistry》1986,101(1):27-31
On the basis of distribution dependences, an analysis of the effect of the macrocomponent (lanthanide) on the extraction of the microcomponent (americium) by benzyl-dialkylamines and benzyltrialkylammonium salts has been made. Assuming the validity of DLn=f(c Ln o ) and DAm=f(c Ln o ), the power function of the general expression log D=logP-Qlog c Ln o has been calculated, the constants have been determination of the equation applying to individual extraction systems and their physical and chemical characteristics have been discussed. 相似文献
3.
From conductimetric measurements, the association constants KA of chlorides and nitrates in acetonitrile and of bromides in both acetonitrile and nitrobenzene were determined in the presence of various amounts of benzoic acids. From these data it was possible to determine the values of the complexation constants k 1 ? between the ligands and the anions. In both solvents linear relationships exist between log k1 and the Hammett σ parameters of the substituents. However, the values of both log k 2 ? for the unsubstituted benzoic acid and the correlation factors (η) are much lower in acetonitrile than in nitrobenzene. It is shown that this effect is due, to a large extent, to the complexation of the ligands by acetonitrile which competes with the ligandanion interaction. The η factors for the three anions lie in the order of their basicity in water. 相似文献
4.
T. V. Aksenova A. N. Petrov V. A. Cherepanov L. Ya. Gavrilova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(8):1215-1220
The oxygen nonstoichiometry δ of lanthanum cobaltite doped with acceptor impurities (Sr and Ni), La1 ? x SrxCo0.9Ni0.1O3 ? δ (x = 0.1, 0.3), was studied by high-temperature thermogravimetry over the temperature and pressure ranges 723 K ≤ T ≤ 1373 K and 10?3 atm ≤ $p_{O_2 } $ ≤ 1 atm. The partial replacement of cobalt with nickel and lanthanum with strontium increased the oxygen nonstoichiometry δ. The partial molar enthalpies $\Delta \bar H^\circ _O $ and entropies $\Delta \bar S^\circ _O $ of solution of oxygen in the solid phase were calculated. Models of point defect formation were suggested and analyzed. The equilibrium constants of formation and concentrations of predominant point defects, ionized oxygen vacancies V o .. , holes Me Co . (Co Co . and Ni Co . ), and electrons Me Co ′ (Co Co ′ and Ni Co ′ ) localized on 3d transition metals, were determined by nonlinear regression from the experimental and theoretical logp $p_{O_2 } $ ?δ dependences. 相似文献
5.
V. V. Dubikhin E. I. Knerel’man G. M. Nazin V. G. Prokudin G. A. Stashina A. V. Shastin I. G. Shunina 《Kinetics and Catalysis》2013,54(4):404-407
A GC-MS analysis of the azobisisobutyronitrile thermal decomposition products of in solutions at 80°C showed that the ratio of recombination and disproportionation rates of the cyanoisopropyl radical does not depend on the medium viscosity, but increases when the internal pressure of the solvent increases according to the log(k dispr/k rec) = ?1.25 + 0.096 P int 0.5 law. This means that the activation volume corresponding to recombination is larger than that corresponding to disproportionation. It follows from the relationship log(k dispr/k rec) = (ΔV rec ≠ ? Δv dispr ≠ )ΔP/RT that, for the decomposition of the substrate in benzene under a pressure of 0.5–4.0 kbar, the difference between the activation volumes is ΔV rec ≠ ? ΔV dispr ≠ = 8 cm3/mol. 相似文献
6.
7.
Tsukasa Sakai 《Journal of Polymer Science.Polymer Physics》1968,6(8):1535-1549
The Huggins constant k′ in the expression for the viscosity of dilute nonelectrolytic polymer solutions, η = η(1 + [η] c + k′[η]2c2 + …), is calculated. For polymers in the theta condition, k′ is estimated to be 0.5 < kθ′ ≤ 0.7. For good solvent systems, the Peterson-Fixman theory of k′ has been modified; the equilibrium radial distribution function in the original theory is replaced with a parametric distribution for interpenetrating macromolecules in the shear force field. Comparison of the modified theory with experimental k′ for polystyrenes and poly(methyl methacrylates) of different molecular weights in various solvents shows good agreement. An empirical equation which correlates the Huggins constant k′ and the viscosity expansion factor αη for polymers has been found to coincide well with the modified theory. 相似文献
8.
This work reports the principle, advantage, and limitations of analytical photoion spectroscopy which has been applied to dissociative photoionization processes for diatomic molecules such as H2, N2, CO, and NO. Characteristic features observed in the differential photoion spectra are summarized with a focus on (pre)dissociation of(i) multielectron excitation states commonly observed in the inner valence regions,(ii) shape resonances, and(iii) doubly charged parent ions. Possible origins for negative peaks in the differential spectra are discussed. This spectroscopy is applied to the reported photoion branching ratios for D2 (and H2 at high energies). The main findings are as follows: (1) The direct dissociation of theX 2Σ g + (1sσ g ) state of D 2 + , the two-electron excited state1Σ u + (2pσ u 2sσ g ) of D2, and the2Σ u + (2pσ u ) state of D 2 + appear clearly in the differential spectrum, as previously observed for H2. (2) Decay of H 2 + (D 2 + ) to H+ (D+) above 38 eV is due to the direct dissociation of highly excited states of H 2 + (D 2 + ) such as the2Σ g + (2sσ g ) and high-lying Rydberg states converging on H 2 2+ (D 2 2+ ). (3) In the ionization continuum of H 2 2+ (D 2 2+ ) peculiar dissociation pathways are observed. The differential photoion spectra for O2 derived from the reported photoion branching ratios are also presented. The (pre)dissociation of theb 4Σ g ? ,B 2Σ g ? , III2Π u ,2Σ u ? , and2,4Σ g ? states of O 2 + appears as the corresponding positive values in the spectra in accord with previous observations. Some other dissociation pathways possibly contributing to the spectra are discussed including dissociative double ionization. 相似文献
9.
The general solvation equation $${\text{Log }}L = c + r \cdot R_2 + s \cdot \pi _2^{\text{H}} + a \cdot \alpha _2^{\text{H}} + b \cdot \beta _2^{\text{H}} + l \cdot \log {\text{ }}L^{16} $$ has been used to evaluate the effect of molecular weight, hydroxyl end groups and temperature on the solubility characteristics of poly(ethylene oxide), PEO. In this equationL is the gas-liquid partition coefficient of a series of probes on PEO, and the explanatory variables are solute properties describing the excess molar refraction,R 2, the probe dipolarity-polarisability, π 2 H , and the probe hydrogen-bond acidity and basicity, α 2 H and β 2 H .L 16 is the gas-liquid partition coefficient of the probe onn hexadecane at 298 K. Ther·R 2 andl·logL 16 terms increased with increase in molecular weight whereas thes·π 2 H and a α 2 H terms decreased; in all cases theb·α 2 H term was not significant. Since thes-constant is a measure of polymer polarity-polarisability, and thea-constant a measure of polymer basicity, we deduce that these polymer properties decrease with increasing molecular weight. Chains with molecular weight below 3000 showed a more rapid decrease in basicity compared to the higher molecular weight species. Thes·π 2 H ,a·α 2 H andl·logL 16 terms all decreased with increase in temperature. Finally, the contribution of the terminal hydroxyl groups to the total polymer basicity was evaluated and discussed. 相似文献
10.
G. M. Rozantsev S. M. Vavilova E. E. Belousova 《Russian Journal of Inorganic Chemistry》2007,52(9):1478-1485
Complex formation in the Nb6O 19 8? -WO 4 2? -H+-H2O system with c Nb : c W = 1 : 5 and varied c Nb + W 0 = 10?2, 5 × 10?3, 2.5 × 10?3, and 10?3 mol/L) has been studied. Distribution diagrams were simulated for individual niobium(V) and tungsten(VI) isopolyanions and mixed isopolyniobotungstates for $Z = \frac{{c_{H^ + }^0 }}{{c_{Nb + W}^0 }} = 0 - 3.0$ in an NaCl background electrolyte. We have shown that isopolyniobotungstates-6 of composition H x NbW5O 19 (3 ? x)? are formed via H x Nb n W6?n O 19 (2 + n ? x)? (n=2, 3, 5) ions. The concentration formation constants and thermodynamic formation constants of isopolyniobotungstate anions (IPNTAs) in aqueous solution have been calculated. Salt Tl3NbW5O19·9H2O has been synthesized and identified by chemical analysis and IR spectroscopy. 相似文献
11.
Y. Saito H. Ito I. Katakuse 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,19(4):189-190
Manganese cluster ions Mn k + (k?60) have been produced by 7 keV Xe ion bombardment and analyzed by a double-focusing mass spectrometer. Discontinuous variations of intensity are found atk=5, 14, 16, 29, 34, 45 and 54. Most of these magic numbers coincide with or differ by only one from those observed in Ar k + . The similarity in magic numbers between Mn k + and Ar k + indicates that the bonding nature in the charged Mn clusters is similar to that in the charged Ar clusters; The polarization force between a positive ion in the center of a cluster and surrounding neutral atoms is dominant binding force. 相似文献
12.
Yuichiro Tada Masakatsu Ueno Noriaki Tsuchihashi Kiyoshi Shimizu 《Journal of solution chemistry》1993,22(12):1135-1149
The limiting molar conductances Λ0 of potassium deuteroxide KOD in D2O and potassium hydroxide KOH in H2O were determined at 25°C as a function of pressure to disclose the difference in the proton-jump mechanism between an OH? (OD?) and a H3O+ (D3O+) ion. The excess conductance of the OD? ion in D2O λ E O (OD -), as estimated by the equation $$\lambda _E^O (OD^ - ) = \Lambda ^O (KOD/D_2 O) - \Lambda ^O (KCl/D_2 O)$$ increases a little with pressure as well as the excess conductance of the OH? ion in H2O $$\lambda _E^O (OH^ - ) = \Lambda ^O (KOH/H_2 O) - \Lambda ^O (KCl/H_2 O)$$ However, their rates of increase with pressure are much smaller than those of the excess deuteron and proton conductances, λ E O (D +) and λ E O (H +). With respect to the isotope effect on the excess conductance, λ E O (OH -)/λ E O (D +) decreases with presure as in the case of λ E O (H +)/λ E O (D +), but the value of λ E O (OH -)/λ E O (OD -) itself is much larger than that of λ E O (H +)/λ E O (D +) at each pressure. These results are ascribed to the difference in the pre-rotation of water molecules, which is brought about by the difference in the intial orientation of the rotating water molecule adjacent to the OH? (OD?) or the H3O+ (D3O+) ion. 相似文献
13.
M. -W. Ruf A. J. Yencha H. Hotop 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,5(1):9-20
Using crossed beams of ground state alkali atoms A (A = Li, Na, K, Rb, Cs) and metastable He(23 S), He(21 S) atoms, we have measured the energy spectra of electrons resulting in the respective Penning ionization processes at: thermal collision energies. The data are interpreted to yield the well depthD e * of the2Σ interaction potentials as follows: He(23 S)+A:D e * (A=Li)=868(20) meV;D e * (Na)=740(25) meV;D e * (K)=591(24) meV;D e * (Rb)=546(18) meV;D e * (Cs)=533(18) meV. He(21 S)+A:D e * (Li)=330(17) meV;D e * (Na)=277(24) meV;D e * (K)=202(23) meV;D e * (Rb)=219(18) meV;D e * (Cs)=277(18) meV. The well depth for He(23 S)+A(2Σ) is always close to 80% of the well depth for Li(2s)+A(X 1Σ). The ionization cross sections for He(21 S)+A are about 3 to 4 times larger than those for He(23 S)+A. 相似文献
14.
B. W. Moudry O. Yenen D. H. Jaecks 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,30(2):199-204
We have measured the alignment and orientation parameters of the2 F 7 2/0 and2 F 5 2/0 states of Ar+ formed in the two-electron process; He++Ar→He(1s 2)+Ar+(3p 44p′). These have been measured at a collision energy of 0.25 keV/amu and for scattering angles ranging from 0.94° to 3.75°. First, by comparing the orientation parameter for the Ar+[(3p 4[1 D]4p′2 F 7 2/0 ] and the Ar+[(3p 4[1 D]4p′2 F 5 2/0 ] states, we have experimentally determined the importance of the spin-dependent interactions for the present collision system, by testing the Percival-Seaton hypothesis of spin independence. If the Percival-Seaton hypothesis holds for this system, the orientation parameter should beJ-independent. Secondly, the magnitude of the orientation parameter can be interpreted as resulting from the collective circulation of the unexcited 3p 4 electrons and the excited 4p electron. The direction of this collective circulation is compared to the propensity rule for colliding di-atom systems. 相似文献
15.
M. K. Chmutova N. E. Kochetkova O. E. Koiro B. F. Myasoedov T. Ya. Medved' N. P. Nesterova M. I. Kabachnik 《Journal of Radioanalytical and Nuclear Chemistry》1983,80(1-2):63-69
Polydentate neutral organophosphorus compounds attract great interest as efficient extractants of transplutonium elements(TPE) from acid waste nuclear fuel element solution. With the view of a further search, reagents R′R″-PO-CH2-CNO-R 2 ″' were synthetized and investigated. The solubility of R 2 ′ POCH2CNOR 2 ″' vas investigated in organic solvents and in nitric acid solutions. This reagent was found to be the best one. 相似文献
16.
Antonio Lo Surdo 《Journal of solution chemistry》1979,8(6):439-447
The relative viscosities ηr of dilute aqueous solutions of azoniaspiroalkane bromides, (CH2) n N+ (CH2) n Br? (wheren=4, 5, and 6), have been measured at 25°C. The viscosityB η andD η coefficients were determined using the extended Jones-Dole equation $$\eta _r = 1 + A_\eta c^{1/2} + B_\eta c + D_\eta c^2$$ TheB η coefficients obtained for the bicyclic azoniaspiroalkane bromides were compared with those of the corresponding homologous tetra-n-alkylammonium bromides. Based on the obtained sign and magnitude of (B n ?0.0025ø v ° ) for the salts and for the bicyclic ions, the structural effects of cation geometry and alkyl group flexibility on water are discussed. The results indicate that the hydrophobic (clathrate hydrate-like) character of the larger tetra-n-alkylammonium ions is reduced significantly when cyclic groups are formed from the alkyl chains in symmetrical quaternary ammonium ions. 相似文献
17.
K. Kleboth 《Monatshefte für Chemie / Chemical Monthly》1968,99(3):1177-1185
The solubility of SiO2 in aqueous solutions of hexafluorosilicates at various acid concentrations has been measured. The results are interpreted in terms of a series of mononuclear siliconfluorine complexes (SiF6, SiF5, SiF4). The equilibrium constants β x6 ′ (x=4 and 5) of the reactionxSiF6+(6?x)SiO2+4(6?x)H=6SiF x +2(6?x)H2O in 4M-LiClO4 have been determined (β 46 ′ =7·10?8, β 56 ′ =9·10?2). The influence of the ionic medium and the likely structures of the complexes are discussed. No conclusion can be drawn as to number and kind of other ligands than F (OH, OH2). 相似文献
18.
The velocity cross correlation integrals $$D_{{\text{ab}}}^{\text{J}} = (N/3)\mathop \smallint \limits_{\text{o}}^\infty< {\text{v}}_{{\text{1a}}} ({\text{t}}) \cdot {\text{v}}_{{\text{2b}}} (0) > {\text{dt,}} {\text{a}} {\text{ = }} {\text{1,2;}} {\text{b}} {\text{ = }} {\text{1,2}}$$ can be estimated from the intradiffusion coefficients D 1 ° and D 2 ° at each mole fraction x1 of component 1 on the basis of the exact relations among the Onsager phenomenological coefficients together with an assumed equation relating the joint diffusion coefficients D ab J . The results from several such equations are compared with experimental data and with similar results derived by Hertz in a different way to represent the behavior of f ab ≡D ab J x b in ideal reference systems. In some cases the agreement with experimental data for relatively ideal systems is even better than given by Hertz's results. For greater accuracy in predicting the D ab J from D a dg data one would need a prediction of the limiting value of D aa J at xa=0 for a=1,2. Presently known theory does not give a basis for estimating this limit reliably. 相似文献
19.
Conductance data are presented for sodium tetraphenylborate (NaBPh4) in three solvent systems: water-dimethyl sulfoxide, water-acetone, and acetone-dimethyl sulfoxide. These and other data from the literature were first analyzed by the three-parameter equation Λ′=Λ0+Aτ2+Bτ3, where $$\Lambda \prime = [\Lambda (obs.) + \beta _0 c^{1/2} (1 + 0.5\tau ln 2\tau )]/[1 - \alpha _0 c^{1/2} + (\tau ^2 /3) ln 2\tau ]$$ Here, β0 is the Onsager electrophoresis coefficient, αoc1/2 the limiting relaxation term, τ=e2κ/2DkT, κ?1 is the Debye-Hückel distance, andA andB are empirical constants. The fact that three parameters are necessary to reproduce the data shows that ion pairing is not negligible for NaBPh4 solutions despite the fact that the conductance curve lies above the limiting tangent even in ethanol (D=24.30). The quantity Λo is the limit of Λ′ at zero concentration; the sum Aτ2+Bτ3 represents the part of the observed conductance from which the pairing constantK Λ and the distance parameterR are derived. Conductance experiments should therefore be designed so that this sum is as large as possible, subject to the restriction that the highest concentration should not exceed 10?7D3 (where the effects of short-range three-ion interactions are no longer negligible). Pairing constants for NaBPh4 in the various solvents range from 4.6 in water to 70 in a mixture of Me2SO and Me2CO with dielectric constantD=23.80. The dependence ofE s (the difference in free energy between solvent-separated pairs and contact pairs) on solvent composition is different for aprotic solvents and for mixtures containing water; for the latter, theE s/kT vs. l/D plot shows a maximum while for the former the curve is monotone descending. The Walden produces (Λoη=limiting conductance times viscosity) plotted againstD ?1 follow the same pattern. 相似文献
20.
R. Loch R. Stengler G. Werth Th. Zenker 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,7(2):189-192
The difference in charge exchange rate in collisions between spin oriented sodium atoms and H 2 + ions has been measured at an energy of about 1 eV. H 2 + was stored in a Penning trap and polarized by spin exchange with Na beam atoms from a hexapole magnet. The ion loss from the trap due to charge exchange was different as we depolarized the atomic beam. From the data we obtain a ratio of cross sections for singlet and triplet collisionsQ 1/Q 3=1.5±0.2 andQ 3=1.2·10?15 cm2. 相似文献