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Standard Molar Enthalpy of Formation of the Solid State Coordination Compound Cu(Nic)2·H2O(s) (Nic = nicotinic acid)

Di Y. Y., Yang W. W., Wang Q. C., Kong Y. X., Tan Z. C.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 3

485-491

EN

A novel compound - monohydrated cupric nicotinate was synthesized by solid phase synthesis at room temperature. FTIR, chemical and elemental analyses, and X-ray powder diffraction technique were applied to characterize the structure and composition of the complex. Enthalpies of dissolution of {Cu(Ac)2 H2O(s)} and {HAc(l)} in 0.1 M HCl solution, {Nic(s)} in 0.1 M HCl solution containing certain amounts of monohydrated cupric acetate, and {Cu(Nic)2 H2O(s)} in 0.1 M HCl solution containing certain amounts of acetic acid at T = 298.15 K were determined by means of an isoperibol solution-reaction calorimeter: DsHCu(Ac) H O o2 2 = -(6.234 ± 0.187) kJ mol-1, DsHHAc o = -(1.788 ± 0.008) kJ mol-1, Ds HNico± = (10.337 ± 0.393) kJ mol-1, and DsHCu(Nic) H Oo2 2 = -(6.801 ± 0.130) kJ mol-1. In accordance with Hess law, a reasonable thermochemical cycle was designed, the enthalpy change of the solid phase reaction of monohydrated cupric acetate with nicotinic acid was determined to be DrHmo = (24.817 ± 0.818) kJ mol-1, and the standard molar enthalpy of formation of the title complex was found to be -(891.463 ± 2.139) kJ mol-1.

2

Thermochemistry of the Coordination Compounds of Zinc Nitrate with Several L-alfa-Amino Acids

Di Y. Y.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 3

599-606

EN

Molar enthalpies of dissolution of {ZnSO4×7H2O(s) + 2NaNO3(s) + L-AA(s)} (in which AA stand for phenylalanine, histidine and methionine) in 100 cm3 of 2 mol×dm-3 HCl at T = (298.15 š 0.001) K have been measured to be deltaHm,1 o = (69.417 š 0.051) kJ×mol-1, (79.830 š 0.058) kJ×mol-1, and (56.929 š 0.051) kJ×mol-1, respectively, by means of an isoperibol solution-reaction calorimeter. Molar enthalpies of dissolution of {Zn(AA)(NO3)2×xH2O(s) + Na2SO4(s)} (in which x = 1 for phenylalanine, x = 1/2 for histidine and methionine) under the same conditions have been determined to be deltaHm,2 o = (48.137 š 0.038) kJ×mol-1, (51.146 š 0.041) kJ×mol-1, and (37.337 š 0.029) kJ×mol-1, respectively, using the calorimeter. The standard molar enthalpies of formation of these complexes Zn(AA)(NO3)2×xH2O(s) have been derived to be delta fHm o [Zn(Phe)(NO3)2×H2O, s, 298.15 K] = -(1367.07 š 3.52) kJ×mol-1, delta fm o [Zn(His)(NO3)2×1/2H2O, s, 298.15 K] = -(1207.19 š 2.82) kJ×mol-1, and delta fHm o [Zn(Met)(NO3)2×1/2H2O, s, 298.15 K] = -(1327.08 š 0.75) kJ×mol-1, respectively, by the combination of the experimental values of enthalpies of dissolution with some auxiliary thermodynamic data through a designed Hess thermochemical cycle on the basis of a supposed chemical reaction.

3

Standard Molar Enthalpy of Formation of Hydrated Sodium Cupric Arsenate [NaCuAsO4×1.5H2O(s)]

Di Y. Y., Chen J. T., Tan Z. C.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 9

1535-1540

EN

A new compound (NaCuAsO4×1.5H2O) was synthesized, and its composition was determined by means of the methods of ignition loss-in-weight and chemical analysis. The standard molar enthalpies of dissolution of the mixtures {Na3AsO4×12H2O(s) + CuSO4×5H2O(s)} and {NaCuAsO4×1.5H2O(s) + Na2SO4(s)} in 1.498 mol×dm–3 HCl so lu - tion at 298.15 K have been determined to be respectively Ds m. H 1 0 = (64322 š 63) J×mol–1 and Ds m. H 2 0 = –(20558 š 25) J×mol–1 using an isoperibol solution-reaction calorimetry. From these values and other thermodynamic data, the standard molar enthalpy of formation of NaCuAsO4×1.5H2O(s) has been de rived: Df m H0 (NaCuAsO4×1.5H2O, s, 298.15 K) = –(1469.33 š 0.65) kJ×mol –1. In addition, UV/Vis spectra and refractive in dexes of solution A and solution A’ were measured to examine the reliability of the designed thermodynamic cycle.

4

The Enthalpy of Formation of Hexagonal Boron Nitride

Tomaszkiewicz I.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 6

891-899

EN

The energies of combustion in fluorine of three specimens of hexagonal boron nitride with different degree of ideal crystalline structure have been measured in a twocompartment calorimetric bomb at 298.15 K according to reaction: BN(cr) + 3/2F2(g) = BF3(g) + 1/2N2(g), and new standard molar enthalpies of formation f m H0 have been calculated and used to rank the samples in order of stability: f m H0 = -(245.8š1.1) kJ/mol for turbostratic sample, that deviates most from the crystalline structure; f m H0 = -(248.5š0.9) kJ/mol for the sample with an interlayer spacing that is only about 0.5% larger than the ideal crystalline h-BN; and f m H0 = -(250.8š1.2) kJ/mol for crystalline h-BN.