TITLE:
Study on Thermodynamics and Kinetics for the Reaction of Magnesium Diboride and Water by Microcalorimetry
AUTHORS:
Fengqi Zhao, Xiaoling Xing, Chuan Xiao, Rongzu Hu, Liang Xue, Hongxu Gao, Libai Xiao, Ting An
KEYWORDS:
Magnesium Diboride, Water, Microcalorimetry, Thermodynamics, Kinetics
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.2 No.2,
May
30,
2011
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, 104.78 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.