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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

2009

Vol. 83, nr 3

485-491

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.

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

2007

Vol. 81, nr 9

1535-1540

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.