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1.
A new magnesium borate Mg2[B2O4(OH)2]·H2O has been synthesized by the method of phase transformation of double salt at hydrothermal condition and characterized by XRD, IR, TG and DSC. The enthalpy of solution of Mg2[B2O4(OH)2]·H2O in 0.9764 mol L–1 HCl was determined. With the incorporation of the enthalpies of solution of H3BO3 in HCl (aq), of MgO in (HCl+H3BO3) (aq), and the standard molar enthalpies of formation of MgO(s), H3BO3(s), and H2O(l), the standard molar enthalpy of formation of –(3185.78±1.91) kJ mol–1 of Mg2[B2O4(OH)2]·H2O was obtained.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
2.
Y. Y. Di Z. C. Tan L. W. Li S. L. Gao L. X. Sun 《Journal of Thermal Analysis and Calorimetry》2007,87(2):545-551
Low-temperature heat capacities of a solid
complex Zn(Val)SO4·H2O(s) were measured by a precision automated adiabatic
calorimeter over the temperature range between 78 and 373 K. The initial dehydration
temperature of the coordination compound was determined to be, T
D=327.05
K, by analysis of the heat-capacity curve. The experimental values of molar
heat capacities were fitted to a polynomial equation of heat capacities (C
p,m) with the reduced temperatures
(x), [x=f (T)], by least
square method. The polynomial fitted values of the molar heat capacities and
fundamental thermodynamic functions of the complex relative to the standard
reference temperature 298.15 K were given with the interval of 5 K.
Enthalpies of dissolution of the [ZnSO4·7H2O(s)+Val(s)] (Δsol
H
m,l
0)
and the Zn(Val)SO4·H2O(s) (Δsol
H
m,2
0) in 100.00 mL of 2 mol dm–3 HCl(aq) at T=298.15
K were determined to be, Δsol
H
m,l
0=(94.588±0.025) kJ mol–1 and Δsol
H
m,2
0=–(46.118±0.055)
kJ mol–1, by means of a homemade isoperibol
solution–reaction calorimeter. The standard molar enthalpy of formation
of the compound was determined as: Δf
H
m
0
(Zn(Val)SO4·H2O(s), 298.15 K)=–(1850.97±1.92) kJ mol–1,
from the enthalpies of dissolution and other auxiliary thermodynamic data
through a Hess thermochemical cycle. Furthermore, the reliability of the Hess
thermochemical cycle was verified by comparing UV/Vis spectra and the refractive
indexes of solution A (from dissolution of the [ZnSO4·7H2O(s)+Val(s)] mixture
in 2 mol dm–3 hydrochloric acid) and solution
A’ (from dissolution of the complex Zn(Val)SO4·H2O(s) in 2 mol dm–3
hydrochloric acid). 相似文献
3.
Wenshen C. Yi L. Chuanpei Z. Songsheng Q. 《Journal of Thermal Analysis and Calorimetry》2001,66(2):463-468
The solid-state coordination reaction: Nd(NO3)3·6H2O(s)+4Ala(s) → Nd(Ala)4(NO3)3·H2O(s)+5H2O(l) and Er(NO3)3·6H2O(s)+4Ala(s) → Er(Ala)4(NO3)3·H2O(s)+5H2O(l) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products
in 2 mol L–1 HCl solvent of
these two solid-solid coordination reactions have been measured using a calorimeter. From the results and other auxiliary
quantities, the standard molar formation enthalpies of [Nd(Ala)4(NO3)3·H2O, s, 298.2 K] and[Er(Ala)4(NO3)3·H2O, s,298.2 K] at 298.2 K have been determined to be Δf
H
m
0 [Nd(Ala)4(NO3)3·H2O,s, 298.2 K]=–3867.2 kJ mol–1, and Δf
H
m
0 [Er(Ala)4(NO3)3·H2O, s, 298.2 K]=–3821.5 kJ mol–1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Masato Machida 《Catalysis Surveys from Japan》2002,5(2):91-102
(n)MnOx–(1–n)CeO2 binary oxides have been studied for the sorptive NO removal and subsequent reduction of NOx sorbed to N2 at low temperatures (150 °C). The solid solution with a fluorite-type structure was found to be effective for oxidative NO adsorption, which yielded nitrate (NO–
3) and/or nitrite (NO–
2) species on the surface depending on temperature, O2 concentration in the gas feed, and composition of the binary oxide (n). A surface reaction model was derived on the basis of XPS, TPD, and DRIFTS analyses. Redox of Mn accompanied by simultaneous oxygen equilibration between the surface and the gas phase promoted the oxidative NO adsorption. The reactivity of the adsorbed NOx toward H2 was examined for MnOx–CeO2 impregnated with Pd, which is known as a nonselective catalyst toward NO–H2 reaction in the presence of excess oxygen. The Pd/MnOx–CeO2 catalyst after saturated by the NO uptake could be regenerated by micropulse injections of H2 at 150 °C. Evidence was presented to show that the role of Pd is to generate reactive hydrogen atoms, which spillover onto the MnOx–CeO2 surface and reduce nitrite/nitrate adsorbing thereon. Because of the lower reducibility of nitrate and the competitive H2–O2 combustion, H2–NO reaction was suppressed to a certain extent in the presence of O2. Nevertheless, Pd/MnOx–CeO2 attained 65% NO-conversion in a steady stream of 0.08% NO, 2% H2, and 6% O2 in He at as low as 150 °C, compared to ca. 30% conversion for Pd/–Al2O3 at the same temperature. The combination of NOx-sorbing materials and H2-activation catalysts is expected to pave the way to development of novel NOx-sorbing catalysts for selective deNOx at very low temperatures. 相似文献
5.
J. B. Anderson M. H. Rapposch C. P. Anderson E. Kostiner 《Monatshefte für Chemie / Chemical Monthly》1980,111(4):789-796
Basic tellurium nitrate crystallizes in the space group Pnma witha=14.607 (1),b=8.801 (1), andc=4.4633 (4) Å. Full-matrix least-squares refinement of automatic diffractometer data converged to a residualR=0.036 (R
w
=0.046) for 899 independent reflections. A detailed analysis of the structural data leads us to reformulate this compound as (Te2O4H)+(NO3)– with a basic structural element consisting of a charged two-dimensional puckered Te2O4H+ network with discrete NO3
– anions, an example of apositively-charged network structure.
Verfeinerung der Kristallstruktur von basischem Telluriumnitrat. Eine Umformulierung in (Te2O4H)+(NO3)–
Zusammenfassung Basisches Telluriumnitrat kristallisiert in der Raumgruppe Pnma mita=14,607 (1),b=8,801 (1) undc=4,4633 (4) Å. Die verfeinernde Auswertung der Diffraktometerdaten konvergierte zuR=0,036 (R w =0.046) für 899 unabhängige Reflexe. Eine detaillierte Analyse der Strukturdaten führte zu einer Umformulierung dieser Verbindung als (Te2O4H)+(NO3)–, wobei die Basisstruktur aus einem geladenen, zweidimensionalen, gefalteten Te2O4H+ Netzwerk mit getrennten NO3 – Anionen besteht. Es stellt dies ein Beispiel einerpositiv geladenen Netzstruktur dar.相似文献
6.
The enthalpies of solution of NaRb[B4O5(OH)4]·4H2O in approximately 1 mol dm−3 aqueous hydrochloric acid and of RbCl in aqueous (hydrochloric acid + boric acid + sodium chloride) were determined. From these results and the enthalpy of solution of H3BO3 in approximately 1 mol dm−3 HCl(aq) and of sodium chloride in aqueous (hydrochloric acid + boric acid), the standard molar enthalpy of formation of −(5128.02 ± 1.94) kJ mol−1 for NaRb[B4O5(OH)4]·4H2O was obtained from the standard molar enthalpies of formation of NaCl(s), RbCl(s), H3BO3(s) and H2O(l). The standard molar entropy of formation of NaRb[B4O5(OH)4]·4H2O was calculated from the Gibbs free energy of formation of NaRb[B4O5(OH)4]·4H2O computed from a group contribution method. 相似文献
7.
The enthalpies of solution of Cs2Ca[B4O5(OH)4]2·8H2O(s) in approximately 1 mol dm−3 aqueous hydrochloric acid and of CsCl(s) in aqueous (hydrochloric acid + boric acid + calcium oxide) were determined. From these results and the enthalpies of solution of H3BO3(s) in approximately 1 mol dm−3 HCl(aq) and of CaO(s) in aqueous (hydrochloric acid + boric acid), the standard molar enthalpy of formation of −(10328 ± 6) kJ mol−1 for Cs2Ca[B4O5(OH)4]2·8H2O(s) was obtained from the standard molar enthalpy of formation of CaO(s), CsCl(s), H3BO3(s) and H2O(l). The standard molar entropy of formation of Cs2Ca[B4O5(OH)4]2·8H2O(s) was calculated from the thermodynamic relation with the standard molar Gibbs free energy of formation of Cs2Ca[B4O5(OH)4]2·8H2O(s) computed from a group contribution method. 相似文献
8.
Dhanpat Rai Dean A. Moore Nancy J. Hess Linfeng Rao Sue B. Clark 《Journal of solution chemistry》2004,33(10):1213-1242
Chromium(III)-phosphate reactions are expected to be important in managing high-level radioactive wastes stored in tanks at many DOE sites. Extensive studies on the solubility of amorphous Cr(III) solids in a wide range of pH (2.8–14) and phosphate concentrations (10–4 to 1.0 m) at room temperature (22±2)°C were carried out to obtain reliable thermodynamic data for important Cr(III)-phosphate reactions. A combination of techniques (XRD, XANES, EXAFS, Raman spectroscopy, total chemical composition, and thermodynamic analyses of solubility data) was used to characterize solid and aqueous species. Contrary to the data recently reported in the literature,(1) only a limited number of aqueous species [Cr(OH)3H2PO–4, Cr(OH)3(H2PO4)2–2), and Cr(OH)3HPO2–4] with up to about four orders of magnitude lower values for the formation constants of these species are required to explain Cr(III)-phosphate reactions in a wide range of pH and phosphate concentrations. The log Ko values of reactions involving these species [Cr(OH)3(aq)+H2PO–4⇌Cr(OH)3H2PO–4; Cr(OH)3(aq)+2H2PO–4⇌Cr(OH)3(H2PO4)2–2; Cr(OH)3(aq)+HPO2–4⇌Cr(OH)3HPO2–4] were found to be 2.78±0.3, 3.48±0.3, and 1.97±0.3, respectively. 相似文献
9.
The kinetics of phenylalanine (phe) oxidation by permanganate has been investigated in absence and presence of cetlytrimethylammonium bromide (CTAB) using conventional spectrophotometric technique. The rate shows first- and fractional-order dependence on [MnO4−] and [phe] in presence of CTAB. At lower values of [CTAB] (≤10.0 × 10−4 mol dm−3), the catalytic ability of CTAB aggregates are strong. In contrast, at higher values of [CTAB] (≥10.0 × 10−4 mol dm−3), the inhibitory effect was observed in absence of H2SO4. We find that anions (Br−, Cl− and NO3−) in the form of sodium salts are strong inhibitors for the CTAB catalyzed oxidation. Kinetic and spectrophotometric evidences for the formation of an intermediate complex and an ion-pair complex between phe and MnO4−, CTAB and MnO4−, respectively, are presented. A mechanism consistent with kinetic results has been discussed. Complex formation constant (Kc) and micellar binding constant (Ks) were calculated at 30 °C and found to be Kc = 319 mol−1 dm−3 and Ks = 1127 mol−1 dm−3, respectively. 相似文献
10.
Syntheses and characterizations of sol–gel precursors of Sr2CeO4 were carried out. Each molecular precursor, [Sr2Ce(OCH2CH2OCH3)8] (1), [Sr2Ce(OiPr)8] (2) and [Sr2Ce2(OiPr)12(iPrOH)4] (3) was prepared from mixtures of Sr complexes and cerium(IV) alkoxides. The molecular structure of 3 showed that [CeO6] octahedra are connected with distorted [SrO6] octahedra by sharing edges with oxo bridges. X-ray powder diffraction patterns and spectrofluorometry were used to determine the evolution of structure from the precursor molecules to the luminescent oxides. The luminescent strontium cerium oxides were derived at relatively mild reaction conditions (700 °C for 1 h), and complete conversion was observed at 1000 °C for 1 h from these precursors. Comparing the spectra of the oxides derived from 2 and 3, the emission intensity of the oxide derived from 2 is much stronger. 相似文献
11.
A pure calcium borate Ca2[B2O4(OH)2]·0.5H2O has been synthesized under hydrothermal condition and characterized by XRD, FT-IR and TG as well as by chemical analysis. The molar enthalpy of solution of Ca2[B2O4(OH)2]·0.5H2O in HC1·54.582H2O was determined. From a combination of this result with measured enthalpies of solution of H3BO3 in HC1·54.561H2O and of CaO in (HCl + H3BO3) solution, together with the standard molar enthalpies of formation of CaO(s), H3BO3(s) and H2O(l), the standard molar enthalpy of formation of −(3172.5 ± 2.5) kJ mol−1 of Ca2[B2O4(OH)2]·0.5H2O was obtained. 相似文献
12.
John E. Nicholas Andrew I. Spiers Nicholas A. Martin 《Plasma Chemistry and Plasma Processing》1986,6(1):39-51
Studies of time-resolved absorption spectra of transient species in the decomposition of NH3 by an r.f. pulse discharge together with product analysis showed that the major radical formed was NH at concentrations of the order of 10–6 mol dm–3 (105 molec. cm–3). Possible mechanisms for the formation of the radical during the discharge and its decay following pulse cut-off were tested by computer simulation of the kinetic data. Following zero-order formation with rate coefficient 0.19±0.03 mol dm–3 s–1, the decay was second order in NH with rate coefficient 2.1±0.5×109 mol–1 dm3 s–1 both for pure NH3 and where NH3/rare gas mixtures were investigated. The kinetic data are consistent with NH removal in a nonassociative radical-radical reaction proceeding via a short-lived collision complex, probably 2NH N2H2 N2 + H2. 相似文献
13.
Chen S.-P. Gao S.-L. Yang X.-W. Shi Q.-Z. 《Russian Journal of Coordination Chemistry》2004,30(8):566-572
The solubility property of Zn(NO3)2–Thr–H2O system (Thr—threonine) at 25°C in the entire concentration range has been investigated by the phase equilibrium semimicromethod. The corresponding phase diagram and refractive index diagram were constructed. From the phase equilibrium results, the incongruently soluble compounds of Zn(Thr)(NO3)2 · 2H2O, Zn(Thr)2(NO3)2 · H2O, and Zn(Thr)3(NO3)2 · H2O were synthesized and characterized by IR, XRD, TG–DTG, chemical and elemental analyses. The constant-volume combustion energies of the compounds,
c
E, determined by precision rotating bomb calorimeter at 298.15 K, were –6266.88 ± 3.72, –9263.28 ± 2.23, and –11 423.11 ± 6.81 J/g, respectively. The standard enthalpies of combustion for these compounds,
c
H
m
° (complex, s., 298.15 K), were calculated as –2147.40 ± 1.28, –4120.83 ± 0.99, and –6444.68 ± 3.85 kJ/mol and the standard enthalpies of formation,
f
H
m
° (complex, s., 298.15 K), are –1632.82 ± 1.43, –1885.55 ± 1.50, and –2770.25 ± 4.21 kJ/mol. The enthalpies of dissolution of the complexes in a medium of simulated human gastric juice (37°C, pH 1, in the solution of hydrochloric acid),
dis
H
m
° (complex, s., 310 K), which were also measured by a microcalorimeter to be 13.36 ± 0.06, 15.53 ± 0.06, and 17.04 ± 0.05 kJ/mol, respectively. 相似文献
14.
The general thermochemical reaction LnCl3·6H2O(c)+3Hthd(1)+73.92H2O(1) = Ln(thd)3(c) +3HCl·26.64H2O(aq); rHm (Ln = Pr, Ho and thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) was employed to determine through solution-reaction calorimetry at 298.15 K the standard molar enthalpies of formation of crystalline chelates, –2434.3±11.5 (Pr) and –2384.8±11.5 (Ho) kJ mol–1. These values and the corresponding molar enthalpies of sublimation enabled the determination of the standard molar enthalpies of chelates in the gaseous phase. From these values the mean enthalpies of the lanthanide-oxygen bond, 265±10 (Pr) and 253±10 (Ho) kJ mol–1 were calculated. 相似文献
15.
Dhanpat Rai Yuanxian Xia Linfeng Rao Nancy J. Hess Andrew R. Felmy Dean A. Moore David E. McCready 《Journal of solution chemistry》2005,34(4):469-498
The objectives of this study were to address uncertainties in the solubility product of (UO2)3(PO4)2⋅4H2O(c) and in the phosphate complexes of U(VI), and more importantly to develop needed thermodynamic data for the Pu(VI)-phosphate system in order to ascertain the extent to which U(VI) and Pu(VI) behave in an analogous fashion. Thus studies were conducted on (UO2)3(PO4)2⋅4H2O(c) and (PuO2)3(PO4)2⋅4H2O(am) solubilities for long-equilibration periods (up to 870 days) in a wide range of pH values (2.5 to 10.5) at fixed phosphate concentrations of 0.001 and 0.01 M, and in a range of phosphate concentrations (0.0001–1.0 M) at fixed pH values of about 3.5. A combination of techniques (XRD, DTA/TG, XAS, and thermodynamic analyses) was used to characterize the reaction products. The U(VI)-phosphate data for the most part agree closely with thermodynamic data presented in Guillaumont et al.,(1) although we cannot verify the existence of several U(VI) hydrolyses and phosphate species and we find the reported value for formation constant of UO2PO−4 is in error by more than two orders of magnitude. A comprehensive thermodynamic model for (PuO2)3(PO4)2⋅4H2O(am) solubility in the H+-Na+-OH−-Cl−-H2PO−4-HPO2−4-PO3−4-H2O system, previously unavailable, is presented and the data shows that the U(VI)-phosphate system is an excellent analog for the Pu(VI)-phosphate system. 相似文献
16.
Summary The hydrolysis ofcis-[CoCl(en)2(bzmH)]2+ (en=ethylenediamine, bzmH=benzimidazole) has been studied over the pH range 8.31–11.58 at I=0.1 mol dm–3 and 25°. Potentiometric titration of aqueous solutions of the [Co(en)2(bzmH)OH2]3+ complex obtained by silver(I) catalysed aquation of the chloro-complex give pK1=5.81 and pK2 = 8.84 for Equilibria (1) and (2) at 25° and I=0.1 mol dm–3. Spectrophotometric titration of the hydroxy complex also gives a value of pK2=8.88 for the ionisation of the coordinated benzimidazole. The kinetic data can be interpreted in terms of base hydrolysis ofcis-[CoCl(en)2(bzmH)]2+ (kOH=220 dm3 mol–1s–1) andcis-[CoCl(en)2(bzm)]+ (kOH=14.9 dm3 mol–1s–1). Comparisons with the corresponding imidazole and pyridine complexes are made. 相似文献
17.
A new magnesium borate MgO·3B2O3·3.5H2O has been synthesized by the method of phase transformation of double salt and characterized by XRD, IR and Raman spectroscopy as well as by TG. The structural formula of this compound was Mg[B6O9(OH)2]·2.5H2O. The enthalpy of solution of MgO·3B2O3·3.5H2O in approximately 1 mol dm−3 HCl was determined. With the incorporation of the standard molar enthalpies of formation of MgO(s), H3BO3(s), and H2O(l), the standard molar enthalpy of formation of −(5595.02±4.85) kJ mol−1 of MgO·3B2O33.5H2O was obtained. Thermodynamic properties of this compound was also calculated by group contribution method. 相似文献
18.
Wen-Sheng C. Yi L. Chuan-Pei Z. Qiang-Guo L. Song-Sheng Q. 《Journal of Thermal Analysis and Calorimetry》2003,73(1):285-291
The solid-state coordination reactions of lanthanum chloride with alanine and glycine, and lanthanum nitrate with alanine
have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in
2 mol L-1 HCl solvent of these three solid-solid coordination reactions have been measured using an isoperibol calorimeter. From the
results and other auxiliary quantities, the standard molar formation enthalpies have been determined to be Δf
H
m
θ[La(Ala)3Cl3·3H2O(s), 298.2 K]= -3716.3 kJ mol-1, Δf
H
m
θ [La(Gly)3Cl3·5H2O(s), 298.2 K]= -4223.0 kJ mol-1 and Δf
H
m
θ [La(Ala)4(NO3)3·H2O(s), 298.2 K]= -3867.57 kJ mol-1, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Selvaraj Kuppusamy Narasimhan Manjula Mallika Jaganathan 《Transition Metal Chemistry》2001,26(1-2):224-227
Ten cobalt(II) nitrate complexes with variously substituted 2,6-diphenylpiperidin-4-ones (L1)–(L10) have been prepared and characterized by elemental analysis, molecular weight determination, molar conductance and magnetic, thermal, polarographic and spectral studies. The formula [Co(L)2(H2O)4](NO3)2 has been assigned to complexes (2–5), (7), (8) and (10) and [Co(L)2(H2O)2(NO3)]NO3 to complexes (1), (6) and (9). Although piperidin-4-ones have two coordinating sites, namely the ring nitrogen and the carbonyl group, i.r., and polarographic studies indicate that only the ring nitrogen is involved in coordination. Electronic spectral data reveal that these complexes have octahedral geometry. 相似文献
20.
Potentially bi- and tetra-dentateSchiff bases derived from salicylaldehyde react with hydrated uranyl salts to give complexes: UO2H2
LX
2, UO2H2
LX
2 and UO2(HL)2
X
2 [H2
L=N,N-propane-1,3-diylbis(salicylideneimine), H2
L=N,N-ethylenebis(salicylideneimine) and HL=N-phenylsalicylideneimine;X
–=Cl–, Br–, I–, NO3
–, ClO4
–, and NCS–]. Because of marked spectral similrities with the structurally known Ca(H2
L) (NO3)2, theSchiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups which carry the protons transferred from phenolic groups on coordination. Halide, nitrate, perchlorate and thiocyanate groups are covalently bonded to the uranyl ion, resulting a 6-coordinated uranium ion in the halo and thiocyanato complexes and 8-coordinated in nitrato and perchlorato complexes.
Komplexe von Dioxouranyl(VI) mit zwitterionischen Formen von zwei- und vierzähnigen Schiff-Basen
Zusammenfassung Von Salizylaldehyd abgeleitete zwei- und vierzähnigeSchiff-Basen reagieren mit hydratisierten Uranylsalzen zu Komplexen folgenden Typs: UO2H2 LX 2, UO2H2 LX 2 und UO2(HL)2 X 2 [H2 L=N,N-Propan-1,3-diylbis(salicylidenimin), H2 L=N,N-Ethylen-bis(salicylidenimin) und HL=N-Phenylsalicylidenimin;X –=Cl–, Br–, I–, NO3 –, ClO4 – und NCS–]. Auf Grund eindeutiger spektraler Ähnlichkeiten mit dem bekannten Ca(H2 L) (NO3)2 wird auf Koordination über die negativ geladenen phenolischen Sauerstoffatome (und nicht über die Azomethin-Stickstoffe) geschlossen. Die AnionenX – sind kovalent an das Uranyl-Ion gebunden; damit ergibt sich ein hexakoordiniertes Uranyl-Ion für die Halogen- und Thiocyanat-Komplexe und Oktakoordination für die Nitrat- und Perchlorat-Komplexe.相似文献