Study on Thermodynamics and Kinetics for the Reaction of Magnesium Diboride and Water by Microcalorimetry

Fengqi Zhao, Xiaoling Xing, Chuan Xiao, Rongzu Hu, Liang Xue, Hongxu Gao, Libai Xiao, Ting An

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DOI: 10.4236/ajac.2011.22033                

Abstract

An exothermic reaction between MgB₂ and water was observed in our laboratory at high temperature, although no obvious reaction occurred at room temperature. The reaction process of MgB₂ and water was therefore studied by using microcalorimetry. The results showed that the reaction enthalpies of MgB₂ with water and the formation enthalpies of MgB₂ at T = (323.15, 328.15, 333.15 and 338.15) K are (–313.15, –317.85, –322.09, –329.27) kJ?mol^–1, and (–238.96, –237.73, –236.50, –234.30) kJ●mol^–1, respectively. The standard enthalpy of formation and standard molar heat capacity of MgB2 obtained by extrapolation method are –245.11 kJ●mol^–1 and 246 J●mol^–1●K^–1, respectively. The values of activation energy E, pre-exponential factor A and the reaction order for the reaction of MgB₂ and water over the temperature range from 323.15 K to 338.15 K are 50.80 kJ●mol^–1, 10^4.78 s^–1 and about 1.346, respectively. The positive values of ΔG^≠ and ΔH^≠ and negative value of ΔS^≠ indicate that the reaction can take place easily above 314.45 K.

Keywords

Magnesium Diboride, Water, Microcalorimetry, Thermodynamics, Kinetics

Conflicts of Interest

The authors declare no conflicts of interest.

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