Synthesis and thermochemistry of SrB2O4·4H2O and SrB2O4 |
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Authors: | Zhi-Hong Liu Hong-Sheng Huang |
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Affiliation: | School of Chemistry and Materials Science, Shaanxi Normal University, Xi’an 710062, PR China |
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Abstract: | Two pure strontium borates SrB2O4·4H2O and SrB2O4 have been synthesized and characterized by means of chemical analysis and XRD, FT-IR, DTA-TG techniques. The molar enthalpies of solution of SrB2O4·4H2O and SrB2O4 in 1 mol dm−3 HCl(aq) were measured to be −(9.92 ± 0.20) kJ mol−1 and −(81.27 ± 0.30) kJ mol−1, respectively. The molar enthalpy of solution of Sr(OH)2·8H2O in (HCl + H3BO3)(aq) were determined to be −(51.69 ± 0.15) kJ mol−1. With the use of the enthalpy of solution of H3BO3 in 1 mol dm−3 HCl(aq), and the standard molar enthalpies of formation for Sr(OH)2·8H2O(s), H3BO3(s), and H2O(l), the standard molar enthalpies of formation of −(3253.1 ± 1.7) kJ mol−1 for SrB2O4·4H2O, and of −(2038.4 ± 1.7) kJ mol−1 for SrB2O4 were obtained. |
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Keywords: | Strontium borates Standard molar enthalpy of formation Solution calorimetry |
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