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  • Author or Editor: K. Tamura x
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Abstract  

Excess thermal expansion factor of non-polar mixtures is the order of 10–6 K–1 and within an experimental error. On the other hand, those of polar mixtures and aqueous solutions are very large and the order of 10–5 K–1, up to the order of 10–4 K–1 in an extreme case. The excess thermal expansion factors express well the excesses of entropy volume cross fluctuation and enthalpy volume cross fluctuation estimated from thermal expansion factor and molar volume. Those of aqueous solutions are, however, reduced by small molar volume of water.

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Abstract  

Excess isobaric heat capacities of mixture (2-methoxyethanol+water) were measured at T=298.15 K and excess enthalpies at T=293.15 and 298.15 K. Excess enthalpies were extremely exothermic, up to -1290 J mol-1 atT=293.15 K and -1240 J mol-1 at T=298.15 K. Excess isobaric heat capacities were positive and very large, approximately 9 J K-1 mol-1 at the maximum. In contrast to the data reported by Page and coworkers, the excess heat capacity data were positive in the entire composition range and there was no change in their signs. Consistently, no crossing was found between the curves of excess enthalpies at T=298.15 and 293.15 K.

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Abstract  

Excess enthalpies, excess heat capacities, excess volumes and sound velocities of the mixture of dioxane isomers, 1,3-dioxane and 1,4-dioxane, were measured. One of the isomers, 1,4-dioxane is considered as non-polar liquid and the other as polar liquid. Excess enthalpies are positive and small, less than 55 J mol-1. Excess heat capacities are also very small and the curve is W-shaped, and the values are from 0.03 to -0.08 J mol-1 K-1. Excess volumes and excess isentropic compressibilities are small and positive, and less than 0.03 cm3 mol-1 and 0.8 TPa-1.

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Abstract  

Densities and sound velocities of binary mixtures of cyclohexanone, 2-butanone, 1,4-dioxane and 1,2-dimethoxyethane were measured at 298.15 K and also the densities at 303.15 K. Excess volumes were determined from densities. Isentropic compressibilities were determined from densities and sound velocities, and excess thermal expansion factors were determined from excess volumes of two temperatures. Excess isothermal compressibilities and excess isochoric heat capacities were then estimated using excess isobaric heat capacities previously reported. Excess volumes and excess isentropic and isothermal compressibilities were negative except for cyclohexanone+1,4-dioxane system.

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Excess enthalpies and excess isobaric heat capacities of binary mixtures consisting of acetonitrile, dimethylformamide and benzene were measured at 298.15 K. Excess enthalpy of acetonitrile + benzene is positive and that of acetonitrile + dimethylformamide is negative. That of dimethylformamide + benzene is positive and nearly equals to zero as shown in the previous report [1]. Excess heat capacities of acetonitrile + benzene and benzene + dimethylformamide change sign from negative to positive with increase of benzene. That of acetonitrile + dimethylformamide is not simple. It is slightly positive near both ends of mole fraction and not so large negative in the middle of mole fraction. The curve tends to flatten in that region.

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Abstract  

Excess enthalpies of six binary mixtures of CH3 OD+CH3 OH, CH3 OD+CD3 OD, CD3 OD+CH3 OH, C2 D5 OD+C2 H5 OH, C2 D5 OD+C2 H5 OD, C2 H5 OD+C2 H5 OH have been determined over the whole range of mole fractions at 298.15 K in order to know the isotopic effect on hydrogen-bonding accurately, although there are many reports on the differences in the strength of hydrogen-bonding between OH and OD. All excess enthalpies measured are very small and endothermic. The mixtures of CH3 OD+ CH3 OH, and C2 D5 OD+C2 H5 OH showed the largest excess enthalpies among each methanol and ethanol mixtures. The difference of intermolecular interaction between OH and OD in methanol and ethanol was almost same value of (1.820.04) J mol-1 Excess enthalpies of 1,4-dimethylbenzene+1,3-dimethylbenzene and 1,4-dimethylbenzene+1,2-methylbenzene were measured by three different principle calorimeters at 298.15 K in order to know the precision of calorimetry for a small enthalpy change.

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Abstract  

The extraction of trivalent lanthanide (Ln(III) ions with two diamides: (1) N,N′-dimethyl-N,N′-diphenyl-malonamide (MA) and (2) N,N′-dimethyl-N,N′-diphenyl-diglycolamide (DGA) from nitric acid solution was studied. Chemical bond properties of extracted complexes were investigated by UV-VIS and FT-IR spectroscopies. The chemical bond strength between Ln(III) ions and the ligands in extracted complexes was closely related with the magnitude of the distribution ratios of Ln(III) ions: the extracted complex having a stronger bond between Ln(III) ion and the ligand showed a higher magnitude of the distribution ratio of Ln(III) ion.

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Abstract  

The extraction behavior of heptavalent technetium with cyclic amides inn-dodecane from nitric acid solution was studied. The amides investigated are N-(2-ethyl)hexylbutyrolactam(EHBLA). N-(2-ethyl)hexylvalerolactam(EHVLA), N-(2-ethyl)hexyl-caprolactam (EHCLA), N-octylcaprolactam(OCLA), a mixture of 3-octyl-N-(2-ethyl)hexylvalerolactam and 4-octyl-N-(2-ethyl)hexylvalerolactam (3,4,OEHVLA), 2-octyl-N-(2-ethyl)hexylcaprolactam(2OEHCLA), a mixture of 3-octyl-N-(2-ethyl)hexylcaprolactam and 5-octyl-N-(2-ethyl)hexylcaprolactam(3,5,OEHCLA) and that of 3-octyl-N-octylcaprolactam and 5-octyl-N-octylcaprolactam(3,5,OOCLA). From the results of the distribution ratio of Tc(VII) as a function of acid concentration, cyclic amides concentration and HTcO4 concentration, the effects of both the ring size of cyclic amide and structure of the substituents attached to different positions of the cyclic ring on the extraction behavior of Tc(VII) were discussed. A clear steric hindrance was observed. For applications, 3,4,OEHVLA is proposed as the best extractant for Tc from acidic solution.

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Abstract  

The complex formation of LaCl3 with dipivaloylmethane (dpm) was investigated in a view of the applicability to a rapid chemistry. It was found that the complex formation of lanthanum chloride with dpm in a gas phase was recognized and a volatile LaCl2 (dpm) which was formed by substitution of a chloride atom in LaCl3 by dpm molecule was mainly produced. A temperature dependence of LaCl2 (dpm) formation was examined and the activation energy of the reaction was deduced.

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