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1.
The heat capacities of NaNO3 and KNO3 were determined from 350 to 800 K by differential scanning calorimetry. Solid-solid transitions and melting were observed at 550 and 583 K for NaNO3 and 406 and 612 K for KNO3, respectively. The entropies associated with the solid-solid transitions were measured to be (8.43± 0.25) J K−1 mole−1 for NaNO3 and (13.8±0.4) J K−1 mole−1 for KNO3. At 298.15 K the values of C0P S0P, {H0(T)-H0(0)}/T and -{G0(T)-H0(0)}/T, respectively, are 91.94, 116.3, 57.73, and 58.55 J K−1 mole−1 for NaNO3 and 95.39, 133.0, 62.93, and 70.02 J K−1 mole−1 for KNO3. Values for S0T, {H0(T)-H0(0)}/T, and -{G0(T)-H0(0)}/T were calculated and tabulated from 15 to 800 K for NaNO3 and KNO3.  相似文献   

2.
Manganese hydrogen phosphate monohydrate, MnHPO4·H2O, a new phase, is synthesized. Its solubility is investigated in the temperature range 35–50°C and pH range 3.4–7.5. Ksp, ΔH0, ΔS0 and ΔG0 for the dissolution are reported. The decrease in solubility with increase in pH is explained as due to a surface coating of insoluble basic phosphate.  相似文献   

3.
The enthalpies of dissolution in water of new ternary complexes of four late trivalent lanthanide ions Ln(Gly)4Im(ClO4)3·nH2O (Ln=Gd, Tb, Dy, Y; Gly: glycine; Im: imidazole and n=1 or 2) were measured by means of a Calvet microcalorimeter. Empirical formulae for the calculation of the enthalpies of dissolution (ΔdissH), relative apparent molar enthalpies (ΔdissH (app)), relative partial molar enthalpies (ΔdissH (partial)) and enthalpies of dilution (ΔdilH1,2) were obtained from the experimental data of the enthalpies of dissolution of these complexes. The plot of ΔdissHmΘ, ΔdissH (app) and ΔdissH (partial) versus the values of the ionic radius of the lanthanide element (r) showed a grouping effect of the lanthanide elements, indicating that the coordinated bond between the lanthanide ions and the ligands has some covalent character. The unknown value of the standard enthalpy of dissolution for the similar complex: Ho(Gly)4Im(ClO4)3·H2O was estimated according to the plot of ΔdissHmΘ versus r.  相似文献   

4.
Raman and infrared spectra of propylgermane, CH3CH2CH2GeH3, and its Ge-deuterated analog, CH3CH2CH2GeD3, were investigated in their gaseous, liquid and solid states. The normal coordinate treatment was carried out by density functional theory (DFT) calculation, using B3LYP/6-31G* and 6-311++G** basis sets, and the corresponding fundamental vibrations were assigned. The trans (T) and gauche (G) forms around the central C–C bond coexisted in the gaseous and liquid states and only the T form existed in the solid state. From the temperature dependent measurements of the Raman spectra in the liquid state, the enthalpy difference was found to be ΔH(TG)=−0.36±0.02 kcalmol−1 with the T form being more stable. The energy differences between the isomers obtained by DFT calculations were ΔE(TG)=−0.46 kcalmol−1 and ΔE(TG)=−0.87 kcalmol−1 by the 6-31G* basis set and 6-311++G** basis set, respectively.  相似文献   

5.
Low-temperature heat capacities of the complex Zn(Thr)SO4·H2O (s) have been precisely measured with a small sample adiabatic calorimeter over the temperature range from 78 to 373 K. The initial dehydration temperature of the complex (Td=325.50 K) has been obtained by analysis of the heat-capacity curve. The experimental values of molar heat capacities have been fitted to a polynomial equation by least square method. The standard molar enthalpy of formation of the complex has been determined from the enthalpies of dissolution (ΔdHmΘ) of [ZnSO4·7H2O (s) +Thr (s)] and Zn(Thr)SO4·H2O (s) in 100 ml of 2 mol dm−3 HCl solvent as: ΔfHm,Zn(Thr)SO4·H2OΘ=−2111.7±3.4 kJ mol−1. These experiments were made by using an isoperibol solution calorimeter at 298.15 K.  相似文献   

6.
The e.m.f. of the galvanic cells Pt,C,Te(l),NiTeO3,NiO/15 YSZ/O2 (Po2 = 0.21 atm),Pt and Pt,C,NiTeO3,Ni3TeO6,NiO/15 YSZ/O2 (Po2 = 0.21 atm),Pt (where 15 YSZ=15 mass% yttria-stabilized zirconia) was measured over the ranges 833–1104 K and 624–964 K respectively, and could be represented by the least-squares expressions E(1)±1.48 (mV) = 888.72 − 0.504277 (K) and E(II) ±4.21 (mV) = 895.26 − 0.81543T (K).

After correcting for the standard state of oxygen in the air reference electrode, and by combining with the standard Gibbs energies of formation of NiO and TeO2 from the literature, the following expressions could be derived for the ΔG°f of NiTeO3 and Ni3TeO6: ΔGf°(NiTeO3) ± 2.03 (kJ mol−1) = −577.30 + 0.26692T (K) and ΔG°f(Ni3TeO6)±2.54 (kJ mol−1) = −1218.66 + 0.58837T (K).  相似文献   


7.
The molecular structure and conformational properties of O=C(N=S(O)F2)2 (carbonylbisimidosulfuryl fluoride) were determined by gas electron diffraction (GED) and quantumchemical calculations (HF/3-21G* and B3LYP/6-31G*). The analysis of the GED intensities resulted in a mixture of 76(12)% synsyn and 24(12)% synanti conformer (ΔH0=H0(synanti)−H0(synsyn)=1.11(32) kcal mol−1) which is in agreement with the interpretation of the IR spectra (68(5)% synsyn and 32(5)% synanti, ΔH0=0.87(11) kcal mol−1). syn and anti describe the orientation of the S=N bonds relative to the C=O bond. In both conformers the S=O bonds of the two N=S(O)F2 groups are trans to the C–N bonds. According to the theoretical calculations, structures with cis orientation of an S=O bond with respect to a C–N bond do not correspond to minima on the energy hyperface. The HF/3-21G* approximation predicts preference of the synanti structure (ΔE=−0.11 kcal mol−1) and the B3LYP/6-31G* method results in an energy difference (ΔE=1.85 kcal mol−1) which is slightly larger than the experimental values. The following geometric parameters for the O=C(N=S)2 skeleton were derived (ra values with 3σ uncertainties): C=O 1.193 (9) Å, C–N 1.365 (9) Å, S=N 1.466 (5) Å, O=C–N 125.1 (6)° and C–N=S 125.3 (10)°. The geometric parameters are reproduced satisfactorily by the HF/3-21G* approximation, except for the C–N=S angle which is too large by ca. 6°. The B3LYP method predicts all bonds to be too long by 0.02–0.05 Å and the C–N=S angle to be too small by ca. 4°.  相似文献   

8.
ΔG0, ΔH0 and ΔS0 protonation values of some pairs of diastereoisomeric dipeptides have been determined by potentiometry and calorimetry in aqueous solution at 25°C and I = 0.1 mol dm−3 (KNO3). On the basis of the results obtained it has been possible to assess the role played by two different non-covalent interactions, namely the electrostatic interaction and the solvophobic interaction, on the thermodynamic stereoselectivity in the proton complex formation, shown by the systems investigated.  相似文献   

9.
Synthesized hydrated lamellar acidic crystalline magadiite (H2Si14O29·2H2O) nanocompound was used as host for intercalation of polar n-alkylmonoamine molecules of the general formula H3C(CH2)nNH2 (n = 1–6) in aqueous solution. The original interlayer distance (d) of 1500 pm, determined by X-ray powder diffraction patterns, increases after intercalation. The values correlated with the number of aliphatic amine carbon (nc) atoms: d = [(1312 ± 11) + (21 ± 2)]nc. The amount of intercalated amines (Ns), decreased as nc increased: Ns = [(5.82 ± 0.04) − (0.45 ± 0.01)]nc. The acidic layered nanocompound was calorimetrically titrated with the amines and the thermodynamic data gave exothermic values for all guest molecules, as shown by the correlation: ΔintH = −[(24.45 ± 0.49) − (1.91 ± 0.10)]nc and d = [(1576 ± 16) − (10.8 ± 1.0)]ΔintH. The negative values of the Gibbs energies and the positive entropies also presented the correlations: ΔintG = −[(22.8 ± 0.2) − (0.2 ± 0.1)]nc and ΔintS = [(6 ± 1) + (5 ± 1)]nc, respectively.  相似文献   

10.
The standard thermodynamic quantities, ΔG0, ΔH0, and ΔS0, associated with the ionization process of benzoic acid in formamide have been evaluated. The standard potentials of the Ag(s)/AgCNS(s)/CNS and the Ag(s)/Ag3Ci(s)/Ci3− electrode, and the standard thermodynamic quantities for the electrode processes have been calculated in formamide, at different temperatures.  相似文献   

11.
Sergey P. Verevkin   《Thermochimica Acta》1998,310(1-2):229-235
The standard enthalpies of formation ΔfHo (liq. or cr.) at the temperature T = 298.15 K were measured using combustion calorimetry for benzophenone (A), 1-indanone (B), -tetralone (C), 9-fluorenone (D), anthrone (E) and dibenzosuberone (F). The standard enthalpies of vaporization ΔvHo or sublimation ΔsHo of A-F and 5,7-dihydro-6H-dibenzo[a,c]cyclohepten-6-one (G) were obtained from the temperature function of the vapor pressure measured in a flow system. Enthalpies of fusion ΔmH of solid compounds were measured by DSC. From the enthalpies of formation of the gaseous compounds of A-G the values of their strain enthalpies were derived and structural effects discussed.

  相似文献   


12.
The compounds (π-C5H5)(CO)2LM-X (L = CO, PR3; M = Mo, W; X = BF4, PF6, AsF6, SbF6) react with H2S, p-MeC6H4SH, Ph2S and Ph2SO(L′) to give ionic complexes [(π-C5H5)(CO)2LML′]+ X. Also sulfur-bridged complexes, [(π-C5H5)(CO)3W---SH---W(CO)3(π-C5H5)]+ AsF6 and [(π-C5H5)(CO)3M-μ-S2C=NCH2Ph-M(CO)3(π-C5H5)], have been obtained. Reactions with SO2 and CS2 have been examined.  相似文献   

13.
14.
A calorimetric study was performed for adducts of general formula CdBr2·nL (n=1 and 2; L=ethyleneurea (eu) and propyleneurea (pu)). The standard molar reaction enthalpy in condensed phase: CdBr2(c)+nL(c)=CdBr2·nL(c); ΔrHmθ, were obtained by reaction–solution calorimetry, to give the following values for mono- and bis-adducts: −19.54 and −34.59; −7.77 and −19.05 kJ mol−1 for eu and pu adducts, respectively. Decomposition (ΔDHmθ) and lattice (ΔMHmθ) enthalpies, as well as the mean cadmium---oxygen bond dissociation enthalpy, DCd---O, were calculated for all adducts.  相似文献   

15.
用中和法合成了氨基酸离子液体(AAIL)1-己基-3-甲基苏氨酸盐[C6mim][Thr],并用核磁共振氢谱(1H NMR)和核磁共振碳谱(13C NMR)进行了表征。以苯甲酸为参考物质,用恒温热重法确定了AAIL[C6mim][Thr]的蒸汽压和在平均温度下(Tav= 438.15 K)的蒸发焓(ΔglHm? (Tav) =128.5 ± 6.0 kJ·mol-1)。利用Verevkin等人提出的方法计算得到AAIL[C6mim][Thr]气态和液态的恒压热容差(ΔglCpm? = -70.8 J·K-1·mol-1),进而计算了不同温度的蒸发焓,其中参考温度(298.15 K)下的蒸发焓ΔglHm? (298.15 K) = 138.4 kJ·mol-1,只比应用我们提出的蒸发焓理论模型估算值大1.6 kJ·mol-1,小于恒温热重法的实验误差3.0 kJ·mol-1,说明这个蒸发焓的理论模型有一定的合理性。借助Clausius-Clapeyron方程估算了AAIL[C6mim][Thr]的假想的正常沸点Tb= 522.07 K,以及沸点的蒸发熵ΔglSm? (Tb) = 228.5 J·K-1·mol-1,进一步得到了不同温度的蒸发熵和蒸发自由能ΔglGm? (T),其结果表明蒸发自由能随着温度的上升而减小,达到沸点温度Tb时变为零,而蒸发熵则随着温度上升而增大,是AAIL[C6mim][Thr]蒸发过程的驱动力。  相似文献   

16.
The enthalpy and entropy of sublimation of N-ethylthiourea were obtained from the temperature dependence of its vapour pressure measured by both the torsion–effusion and the Knudsen effusion method in the temperature range 360–380 K. The compound undergoes no solid-to-solid phase transition or decomposition below 380 K. The pressure against reciprocal temperature resulted in lg(p, kPa) = (13.40 ± 0.27) − (6067 ± 102) /T(K). The molar sublimation enthalpy and entropy at the mid interval temperature were ΔsubHm(370 K) = (116.1 ± 2.0) kJ mol−1 and ΔsubSm(370 K) = (218.0 ± 5.2) J mol−1 K−1, respectively. The same quantities derived at 298.15 K were (118.8 ± 2.1) kJ mol−1 and (226.1 ± 5.5) J mol−1 K−1, respectively.  相似文献   

17.
In this work, the interaction between chelerythrine (CHE) and guanosine is studied using UV-vis and fluorescence measurements at various temperatures. The UV-vis spectra show that the increasing guanosine concentrations result in the decreasing absorption intensity and red shift of CHE E absorption band (267 nm). The fluorescence spectra are fitted to linear analysis, yielding a binding constant of 1.04×104 L/mol at 298.15 K of CHE with guanosine. Besides, with △rHΘm =-8.26 kJ/mol, △rGmΘ = -22.90 kJ/mol,and △rSmΘ = 49.38 J/(mol K) the interaction should be entropy-driven and exterothermic.  相似文献   

18.
《Thermochimica Acta》1991,190(2):319-323
Measurements were made of the dissolution heats of NaBPh4 and Ph4PCl in water-n-propanol mixtures over the whole range of compositions. Assuming the equality of ΔHtr+(Ph4P+) and ΔHtr+(BPh4), the transfer enthalpies of several ions from water to water-n-propanol mixtures at 298.15 K were calculated.  相似文献   

19.
We studied the isotope, pressure and doping effects on the pseudogap temperature T* by neutron spectroscopic experiments of the relaxation rate of crystal-field excitations in La1.96−xSrxHo0.04CuO4 (x = 0.11, 0.15, 0.20, 0.25) on the high-resolution time-of-flight spectrometer FOCUS at SINQ, PSI. We found clear evidence for the opening of a pseudogap in the underdoped regime at T*(x = 0.11) = (82.2 ± 1.2) K as well as in the overdoped and the heavily overdoped compounds at T*(x = 0.2) = (49.2 ± 0.7) K and at T*(x = 0.25) = (46.5 ± 0.5) K, respectively. Furthermore, we investigated the effect of oxygen isotope substitution on the pseudogap, the experiments revealed ΔT*(x = 0.11) = (21.3 ± 5.2) K and ΔT*(x = 0.2) = (4.5 ± 1.3) K. The application of hydrostatic pressure (0.8 and 1.2 GPa) on the optimally doped compound (x = 0.15) results in a downward shift of dT*/dp = (−5.9 ± 1.6) K/GPa.  相似文献   

20.
Liposomes can be effectively deposited on the inner surface of a capillary wall by flushing the electrophoretic system with a liposome suspension followed by air-drying of the capillary and removal of the excess of loosely bound liposomes by a 0.1 M NaOH wash. It was demonstrated that capillaries prepared in this way could be used for studies of analyte (drug)–liposome binding. The results were expressed as free binding energy changes [Δ(ΔG0)] relatively to an arbitrarily selected standard (acetylsalicylic acid). The results were compared to [Δ(ΔG0)] changes obtained from binding studies effected by capillary electrophoresis using a stable liposome plug in a capillary with minimized endoosmotic flow. Good agreement of data reported in the literature (without correction for the residual endoosmotic flow), our previous data obtained in a similar way (however, after the correction for the residual endoosmotic flow) and data obtained by the immobilized liposome affinity electrochromatography reported in this communication was achieved.  相似文献   

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