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121.
铝酸钠溶液的紫外吸收峰 总被引:4,自引:0,他引:4
分别用量子化学MNDO和DV-X_α方法计算了二聚铝酸离子[Al_2O(OH)_6]~(2-)和Al(OH)_4~-。结果表明前者旋转势垒很低, 只有10.08 kJ·mol~(-1), 最稳定平衡构型为C_s。用X_α过渡态理论计算获得这两个离子紫外吸收峰的理论值分别为266.6 nm和234.4 nm, 与实验值270.0 nm和230.0 nm相当接近。因此可以认为, 紫外吸收峰270.0 nm和230.0 nm分别为[Al_2O(OH)_6]~(2-)和Al(OH)_4~-离子的最高占有轨道电子向最低空轨道跃迁时产生的吸收峰。计算结果支持铝酸钠溶液中存在二聚铝酸离子的观点。 相似文献
122.
Alexander R. Giaquinto Richard E. Lindstrom James Swarbrick Antonio LoSurdo 《Journal of solution chemistry》1977,6(10):687-701
Solubility and apparent molar volume data are used to demonstrate effects of amide alkylation on amide-water interactions at 25° C. Precise measurements were made of the apparent molar volumes of the amides in binary amide-water mixtures using a dilatometric technique. The results show that the apparent molar volumes of alkyl-substituted amides in water pass through a minimum at an amide concentration which varies inversely with the degree of alkylation. Further studies showed that the solubilities of methyl paraben (methyl-p-hydroxybenzoate) and naphthalene in various amide-water solvent systems increased in characteristic fashion with amide alkylation. 相似文献
123.
Darja?Rudan-Tasic Cveto?KlofutarEmail author 《Monatshefte für Chemie / Chemical Monthly》2004,135(7):773-784
Summary. The freezing temperatures of dilute aqueous solutions of some poly(oxyethylene) glycols (PEG, HO–(CH2CH2O)
n
–H, n varying from 4 to 117) were measured over a solute to solvent mass ratio from 0.0100 to 0.3900. The second and third osmotic virial coefficient (A
22 and A
222) of poly(oxyethylene) glycols in aqueous solution were determined. The molecular weight dependence of the second virial coefficient can be described by a simple relation A
22=2×10–5
M
n
1.86, and the third virial coefficient is A
222=0.038A
22
2. The activity coefficients of the solute were calculated using the Gibbs-Duhem equation as applied by Bjerrum. From the osmotic and activity coefficients the excess Gibbs energies of solution, as well as the respective partial molar functions of solute and solvent and the virial pair interaction coefficients for the excess Gibbs energies were estimated. The second and the third osmotic virial coefficients are correlated with the Mc-Millan-Mayer virial coefficients. 相似文献
124.
Ion Association and Hydration in Aqueous Solutions of Nickel(II) and Cobalt(II) Sulfate 总被引:1,自引:0,他引:1
Ting?Chen Glenn?HefterEmail author Richard?Buchner 《Journal of solution chemistry》2005,34(9):1045-1066
Aqueous solutions of nickel(II) and cobalt(II) sulfate have been investigated at 25 ∘C by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν (GHz) ≤ 89) and salt concentrations
(0.025 ≤ c(mol-L−1) ≤ 1.4). The spectra indicate, as for MgSO4(aq) studied previously, the simultaneous presence of double solvent-separated, solvent-shared and contact ion pairs in both
NiSO4(aq) and CoSO4(aq). The stepwise formation constants for each ion-pair type and the overall association constant, obtained from the data
are in good agreement with ultrasonic relaxation and other estimates. The DR spectra at higher concentrations (c ≥ 0.5 mol-L−1) suggest the existence of a nonlinear triple ion M2SO42+(aq). Consistent with the very strong hydration of the salts, which have ‘effective’ hydration numbers approaching 27 at infinite
dilution, there are no significant differences in any of the relaxation or thermodynamic parameters for NiSO4(aq) and CoSO4(aq), except that the triple ion appears to be somewhat more stable for the latter. 相似文献
125.
Room temperature Raman spectra of synthesized powder (FexMg1?x )2SiO4 solid solutions are obtained. Frequency trend of all modes versus composition shows clearly the existence of a step at x = 0.3. A step-like behavior of vibration frequencies at the given composition that coincides with the percolation threshold for the olivine lattice is related to the appearance of magnetic excitations in the disordered magnetic medium owing to the spin-vibration interaction. 相似文献
126.
E. U. Franck 《Journal of solution chemistry》1973,2(2-3):339-356
A survey is given of recent experimental results obtained from high-temperature, high-pressure investigations with water, aqueous solutions, and ionic fluids. Data on the static dielectric constant of water to 550°C and 5 kbar are given and discussed with respect to their relation to water structure. Infrared and Raman spectra of HDO in pure water have been obtained to 400°C and 4 kbar, which give information on hydrogen bonding. Xe–H2O and CO2–H2O mixtures were investigated in the infrared. Ni(II) and Cu(II) complexes were investigated by absorption spectroscopy in aqueous solutions of high chloride content to 350°C and 2–6 kbar. The gas-liquid critical point of ammonium chloride was found at 880°C and 1635 bars. This fluid appears to be predominantly ionic even in the critical region. The possibility of converting pure polar fluids such as ammonia and water into concentrated ionic solutions by self-ionization at very high pressures is mentioned.This paper was presented at the symposium, The Physical Chemistry of Aqueous Systems, held at the University of Pittsburgh, Pittsburgh, Pennsylvania, June 12–14, 1972, in honor of the 70th birthday of Professor H. S. Frank. 相似文献
127.
A. G. Matveeva E. I. Matrosov Z. A. Starikova G. V. Bodrin S. V. Matveev P. V. Petrovskii E. E. Nifant’ev 《Russian Chemical Bulletin》2005,54(11):2519-2534
The trifunctional ligand, 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol (L
2), forms complexes with cerium(III) nitrate having a ligand to metal ratio of 1: 1, 2: 1, and 3: 1. The structures of these complexes in the solid state and
in solution were studied by X-ray diffraction, IR and NMR (1H and 31P) spectroscopy, and conformational analysis (molecular mechanics). The 2: 1 complexes of L
2 with lanthanum(III) and neodymium(III) nitrates were synthesized and characterized. In all complexes, the neutral ligand is coordinated through both phosphoryl
oxygen atoms. The hydroxy oxygen atom is coordinated only in some complexes, and the hydrogen atom of the hydroxy group is
involved in hydrogen bonding. The compositions and structures of the resulting complexes depend on the method of synthesis
and the nature of solvent. The ligand was found to undergo easy inner-sphere oxidation. The structure of one of the transformation
products was established by X-ray diffraction. Unlike the coordinated ligand, the free ligand is very stable to oxidation.
Dedicated to Corresponding Member of the Russian Academy of Sciences T. A. Mastryukova.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2440–2454, November, 2005. 相似文献
128.
Penna Thereza Christina Vessoni Marques Marcelo Machoshvili Irena A. Ishii Marina 《Applied biochemistry and biotechnology》2002,98(1-9):539-551
Large-volume parenteral solutions were submitted to heat treatments after being inoculated with Bacillus stearothermophilus ATCC 7953 (T
r
=121°C) and Bacillus subtilis ATCC 9372 (T
r
=104.5°C) spores. The average decimal reduction time for B. stearothermophilus ranged from a D
121°C value of 1.31 to 3.14 min, in glucophysiologic and Ringer’s solutions respectively. For B. subtilis, D
104.5°C value increased from 0.69 to 1.37 min, in Ringer’s (pH=5.91) and 50% glucose (pH 3.05) solutions respectively. The z value ranged from 7.95°C (20% mannitol solution) to 13.14°C (50% glucose solution), corresponding to an activation energy
(Ea) of 81.48 and 49.30 kcal/mol, respectively. 相似文献
129.
P. Torline G. du Plessis N. Schnautz J. C. Thompson 《Journal of separation science》1979,2(10):613-616
A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible. 相似文献
130.
本文主要研究非线性复微分方程f^(4)+a(z)ff^((k))=p_(1)(z)e^(α_(1)(z))+p_(2)(z)e^(α_(2)(z))的超越亚纯解,其中a,p_(1),p_(2)是非零的有理函数,α_(1),α_(2)是非常数的多项式.进一步地,考虑当亚纯解存在时,α_(1),α_(2),p_(1)和p_(2)所满足的条件.另外,还讨论了非线性复微分方程f^(3)+a(z)f’=p_(1)(z)e^(ν(z))+p_(2)(z)e^(-ν(z))的亚纯解的存在性,其中a,p_(1),p_(2)是非零的有理函数,ν是非常数的多项式.所得的结果直接推广了一些已知的结果. 相似文献