硝酸钕和钐的水合物在水中溶解热的测定

本文用补偿式数字量热计测定了六水、四水硝酸钕和六水、五水硝酸钐298.15K时在水中的溶解热,求得了它们的标准生成热、相应的标准脱水焓和晶格能。     

Humidity controlled calorimetric investigation of the hydration of MgSO4 hydrates

The isothermal heat of hydration of MgSO₄ hydrates was studied by humidity controlled calorimetry. Two hydrates, starkeyite (MgSO₄·4H₂O) and a mixture of MgSO₄ hydrates with summary 1.3 mol H₂O were investigated. The solid-gas reactions were initiated at 30°C and 85% relative humidity. The heat of hydration was determined in a circulation cell in the calorimeter C80 (Setaram). The crystal phases formed after the hydration process were analyzed by thermogravimetry (TG) and X-ray powder diffraction (XRD). Starkeyite reacted with the water vapour to the thermodynamic stable epsomite and the MgSO₄ hydrate mixture with 1.3 mol water to hexahydrite. The hydration heats of starkeyite and the mixture were determined to be −169±3 and −257±5 kJmol⁻¹, respectively.     

Thermochemical properties of anhydrous and hydrated alkaline-earth metal and magnesium perchlorates

A low-temperature method of obtaining anhydrous magnesium, calcium, strontium, and barium perchlorates and their hydrates was developed. Hexa-Mg(ClO₄)₂, Sr· (ClO₄)₂·H₂O, and Ba(ClO₄)₂·H₂O were prepared for the first time. The enthalpies of dissolution of anhydrous magnesium and strontium perchlorates and Mg, Ca, Sr, and Ba perchlorate hydrates in water were measured; the standard enthalpies of their formation were determined. The enthalpies of dehydration of M(ClO₄)₂· nH₂O in stages were determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1978–1983, September, 1989.     

Higher hydrates of lithium chloride,lithium bromide and lithium iodide

For lithium halides, LiX (X = Cl, Br and I), hydrates with a water content of 1, 2, 3 and 5 moles of water per formula unit are known as phases in aqueous solid–liquid equilibria. The crystal structures of the monohydrates of LiCl and LiBr are known, but no crystal structures have been reported so far for the higher hydrates, apart from LiI·3H₂O. In this study, the crystal structures of the di‐ and trihydrates of lithium chloride, lithium bromide and lithium iodide, and the pentahydrates of lithium chloride and lithium bromide have been determined. In each hydrate, the lithium cation is coordinated octahedrally. The dihydrates crystallize in the NaCl·2H₂O or NaI·2H₂O type structure. Surprisingly, in the tri‐ and pentahydrates of LiCl and LiBr, one water molecule per Li⁺ ion remains uncoordinated. For LiI·3H₂O, the LiClO₄·3H₂O structure type was confirmed and the H‐atom positions have been fixed. The hydrogen‐bond networks in the various structures are discussed in detail. Contrary to the monohydrates, the structures of the higher hydrates show no disorder.     

Kinetic Analysis of Dissociation of Smithsonite from a Set of Non-isothermal Data Obtained at Different Heating Rates

The heats of hydration reactions for MgCl₂⋅4H₂O and MgCl₂⋅2H₂O include two parts, reaction enthalpy and adsorption heat of aqueous vapor on the surfaces of magnesium chloride hydrates. The hydration heat for the reactions MgCl₂⋅4H₂O+2H₂O→MgCl₂⋅6H₂O and MgCl₂⋅2H₂O+2H₂O→MgCl₂⋅4H₂O, measured by DSC-111, is –30.36 and –133.94 kJ mol^–1,respectively. The adsorption heat of these hydration processes, measured by head-on chromatography method, is –13.06 and –16.11 kJ mol^–1, respectively. The molar enthalpy change for the above two reactions is –16.64 and –118.09 kJ mol^–1, respectively. The comparison between the experimental data and the theoretical values for these hydration processes indicates that the results obtained in this study are quite reliable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Y(NCS)3·4(1/2)H2O和Y(NCS)3·2(1/2)H2O的制备、性质及标准生成焓的测定

本文首次制备了异硫氰酸钇低水合物Y(NCS)₃·4 1/2H₂O和Y(NCS)₃·2 1/2H₂O,采用量热法测定了它们在298.15K时的标准生成焓,进而计算了它们的晶格能以及相应的标准脱水焓。     

Coordination characteristics of trivalent lanthanides and actinides in molten hydrate salts of Ca(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> and CaCl<Subscript>2</Subscript>

Distribution behavior of Ce(III), Am(III), and Cm(III) between tri-n-butyl phosphate solution and molten calcium nitrate hydrate Ca(NO₃)₂·RH₂O or molten calcium chloride hydrate CaCl₂·RH₂O was studied radiochemically. In Ca(NO₃)₂·RH₂O systems, maximum separation factors of Ce and Cm to Am were observed to be 12 (Ce/Am) and 1.7 (Cm/Am). The distribution ratios of these elements increased with the decrease of water activity in the hydrates, and the extractabilities at the water deficient region was less sensitive compared to those at the water abundant region. This trend was similar to the coordination circumstance change observed in electronic absorption spectra of Nd(III) in the hydrates.     

Zur Kenntnis der Phase BaO · Al2O3 · 7 H2O

On the Compound BaO · Al₂O₃ · 7 H₂O On the basis of investigations using ²⁷Al, ¹H NMR, IR and thermoanalytical methods for the compound BaO · Al₂O₃ · 7 H₂O a constitution as Ba_n[Al₂(OH)₈]_n · 3n H₂O with condensed AlO₆ groups, sharing edges, is proposed. Relations between the Ba/Al ratio and the constitution of anions of barium aluminate hydrates are discussed.     

Determination calorimetrique de l'enthalpie de formation des alliages (Al,Ba) riches en aluminum

The heats of formation of some aluminium-barium alloys have been determined by drop calorimetry at high temperature. The heats of mixing of pure liquid Al and Ba to give the liquid alloy are Δ_mH(x_Ba=O.056, 1215 K)=?6.6 kJ mole^?1 and Δ_mH(x_Ba=O.333, 1215 K)=?31.0 kJ mole^-1. To measure its heat of formation, the solid compound Al₄Ba was precipitated by addition of pure barium from a liquid (Al, Ba) bath. It was found that Δ_fH(Al_0.8Ba_O.2, solid, 1215 K)=-(37.1 ? 1.5) kJ mole^?1 with reference to the pure metals in the solid state.     

Reduction of nitrogen with neodymium(II) and dysprosium(II) diiodides and selected properties of the resulting nitrides

The diiodides NdI₂ and DyI₂ react with nitrogen at an atmospheric pressure at 2704-550 °C to give the nitrides (LnI₂)₃N (Ln = Nd and Dy). The products obtained are insoluble in organic solvents; in THF, they rapidly disproportionate into LnI₃(THF)₃ and the iodide nitrides (NdI)₃N₂ of unclear structures. The nitrides (NdI₂)₃N and (DyI₂)₃N can be completely hydrolyzed into ammonia, the triiodide hydrates LnI₃(H₂O)₂, and the monoiodide hydrates LnI(OH)₂(H₂O). A reaction of (NdI₂)₃N with excess iodobenzene in THF gives Ph₃N and PhNH₂ in 9 and 5% yields, respectively. Reactions of (NdI₂)₃N with propyl chloride, benzyl chloride, and acetyl chloride produce no nitrogen-containing products. A reaction of (NdI₂)₃N with CpK gives Cp₃Nd(THF) in 63% yield.     

The heat of dehydration of concentrated sodium chloride and potassium chloride solutions

The molar heats of dehydration, ΔH¯_dehyd., of concentrated sodium chloride and potassium chloride solutions were measured with a differential scanning calorimeter in the scanning and isothermal modes. The overall ΔH¯_dehyd. was found to be 44.5 and 44.3 kJ mole^?1 H₂O for NaCl and KCl solutions respectively. There is an astonishing difference between concentrated NaCl and KCl solutions in the way water is lost. The number of fractions of heat dehydration were 2 for NaCl and 3 for KCl. The excess ΔH¯_dehyd. was about 10 kJ mole^?1 H₂O for fraction II of NaCl, and 17 and 55 kJ mole^?1 H₂O for fractions II and III, respectively, of KCl.     

SrCl2 · 1/2 H2O und SrCl2 · H2O Röntgenographische,thermoanalytische, Raman- und IR-spektroskopische Untersuchungen

SrCI₂ · 1/2 H₂O and SrCl₂ · H₂O. X-ray, Thermalanalytical, Raman, and I. R. Data The formation of the new compound SrCI₂ · 1/2 H₂O was detected with help of high-temperature X-ray and high-temperature Raman measurements. Strontium chloride hemihydrate was prepared by dehydration of the higher hydrates in a water-vapour atmosphere of 1 bar at 165 °C. The Course of dehydration of SrCI₂ · 6 H₂O, and SrCI₂ · 2 H₂O is discussed. X-ray, i.r.-and Raman data of SrCI₂ · 1/2 H₂O and SrCl₂ · H₂O are reported. SrCI₂ · H₂O crystallizes ortho-rhombic in the BaCI₂ · H₂O type (space group Pnma) with a = 1088.1(1), b = 416.2(1), and c = 886.4(1) pm. The water modes of the hydrates as well as the force constants and bond energies of the hydrogen bridges are discussed.     

Hydrogen bonding and structure of Ba2Ru2Cl10O·10H2O

Dibarium μ‐oxido‐bis[pentachloridoruthenate(IV)] decahydrate, Ba₂Ru₂Cl₁₀O·10H₂O, has been prepared from ruthenium(III) chloride and barium chloride in hydrochloric acid. It crystallizes in the monoclinic system (space group C2/c). The structure consists of alternating layers of [Ru₂Cl₁₀O]⁴⁻ and [Ba(H₂O)₇]²⁺ complex ions along the a direction. The O atom bonded to ruthenium occupies the 4e site, with symmetry, while the other atoms occupy general 8f sites. The overall structure is held together by O—H...O hydrogen bonds and O—H...Cl dipole–dipole interactions.     

Comparison of properties of solutions of alkylammonium salts in water and in solvents having low dielectric constants

The integral heats of solution H_m of tetrabutylammonium nitrate in water at 25 C have been measured over the concentration range from 0.005 to 12 moles of salt per 1000 g H₂O. The integral heats of dilution H _m ⁰ and the relative partial molar (rpm) enthalpy of the solvent ¯L₁ and solute ¯L₂ have been calculated. It follows from the data obtained that the salt has a strong ordering effect on the structure of water. A comparison of the thermochemical characteristics of aqueous solutions of tetrabutylammonium bromide, chloride, and nitrate enables us to attribute this high ordering action of the salt on the structure of water to the cation (C₄H₉)N⁺. Anions, of which NO ₃ ^– is known to be the strongest destructive agent, compensate the effect of the cation on the curves for the relationship ¯L₁/T=f(m) which are in the region of large negative values for all three salts. In the concentration region m=3–5 moles of salt per 1000 g H₂O, the relationships we obtained and those calculated from data in the literature have extrema. It is proposed that clathrate hydrates of definite composition exist in solution. Generally, the results obtained do not contradict the Frank hydrate model.     

Über basische Aluminiumsalze und ihre Lösungen. VI. Darstellung und Charakterisierung eines wasserlöslichen Al13O40-Chlorides

Basic Aluminium Salts and their Solutions. VI. Preparation and Characterization of a Water-soluble Al₁₃O₄₀ Chloride The water-soluble chloride is prepared from the sparingly soluble basic aluminium sulfate [Al₁₃O₄(OH)₂₅(H₂O)₁₁](SO₄)₃ · xH₂O by reaction with barium chloride. From kinetic and ²⁷Al NMR measurements is concluded, that the solid chloride as well as its aqueous solution contain exclusively the Al₁₃O₄₀ cation. It is shown by differential thermal analysis that the solid chloride includes water in different linkage.     

Radiational centers in barium hydroxide and its crystal hydrates

The formation and stabilization of hole and electron centers at 77 K in -irradiated polycrystalline samples of Ba(OH)₂·H₂O, where x=7.4, 1, and O are studied. Several types of O^– radical ions with different short-range order, electronic centers of the F_A-center type, and hydrogen atoms are shown to be stabilized upon radiolysis of barium hydroxide crystal hydrates. The radiation-chemical yields of 0 radical ions increase and the yields of F_A-centers decrease with increasing content of water of crystallization. Narrow singlets with g=2.019 and H_1/2=0.45 mT in the EPR spectrum of all samples appear with small radiation doses. These are thermally unstable (_1/2=60 sec at 77 K). The annealing curves are linear in semilogarithmic coordinates. They are suggested to belong to clusters of the type Ba _n ^2n-x . A possible mechanism of radiolysis of barium hydroxide crystal hydrates is proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2176–2182, October, 1989.     

Clathrate Hydrates of Tetrabutylammonium and Tetraisoamylammonium Halides

Clathrate formation was considered for two series of systems: (C₄H₉)₄NG–H₂O and iC₅H₁₁)₄NG–H₂O G = F^-, Cl^-, Br^-, I^-). Clathrate hydrates of tetraisoamylammonium halides were shown to melt at higher temperatures than those of the butyl series. In passing from fluoride to bromide, the stability of compounds of the butyl series falls significantly and tetrabutylammonium iodide does not produce polyhydrates. In the isoamyl series, the melting points of polyhydrates vary insignificantly for different halides. In addition, the highest melting hydrate of tetraisoamylammonium bromide melts at a slightly higher temperature than chloride hydrates, indicating not only a hydrophilic effect of the anion on clathrate formation.     

The heats of fusion of tetrabutylammonium fluoride ionic clathrate hydrates

Two ionic clathrate hydrates with different structures are formed in the binary system tetrabutylammonium fluoride–water, namely tetragonal structure-I hydrate (TS-I) (n-С₄H₉)₄NF · 32.8H₂O, and cubic superstructure-I hydrate (CSS-I) (n-С₄H₉)₄NF · 29.7H₂O. The heats of fusion (ΔH_f) of these polyhydrates were measured calorimetrically with differential scanning calorimeter. For TS-I polyhydrate ΔH_f = (204.8 ± 2.3) kJ/mol hydrate, for CSS-I hydrate ΔH_f = (177.5 ± 3.1) kJ/mol polyhydrate. The change of water molecules energy state in the water lattices of TS-I and CSS-I polyhydrates are discussed.     

Crystal structures of hydrates of simple inorganic salts. III. Water‐rich aluminium halide hydrates: AlCl3·15H2O,AlBr3·15H2O,AlI3·15H2O,AlI3·17H2O and AlBr3·9H2O

Water‐rich aluminium halide hydrate structures are not known in the literature. The highest known water content per Al atom is nine for the perchlorate and fluoride. The nonahydrate of aluminium bromide, stable pentadecahydrates of aluminium chloride, bromide and iodide, and a metastable heptadecahydrate of the iodide have now been crystallized from low‐temperature solutions. The structures of these hydrates were determined and are discussed in terms of the development of cation hydration spheres. The pentadecahydrate of the chloride and bromide are isostructural. In AlI₃·15H₂O, half of the Al³⁺ cations are surrounded by two complete hydration spheres, with six H₂O in the primary and 12 in the secondary. For the heptadecahydrate of aluminium iodide, this hydration was found for every Al³⁺.     

Effect of anion size on clathrate formation in butyltriisopentylammonium halide-water systems

Three clathrate hydrates i-Pent₃BuNCl · 38H₂O, i-Pent₃BuNCl·32H₂O, and i-Pent₃BuNCl·27H₂O, as well as triisopentylammonium dihydrate were found in the system i-Pent₃BuNCl-H₂O. Crystals of all the hydrates were isolated, and their compositions were determined. The effect of anion size on the formation of clathrates involving the triisopentylammonium cation was studied.