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Experimental studies on the stability of several Mg-sulfate hydrates including epsomite (MgSO4·7H2O), hexahydrite (MgSO4·6H2O), starkeyite (MgSO4·4H2O), and kieserite (MgSO4·H2O) as a function of temperature and relative humidity are in poor agreement with calculations based on thermodynamic properties of these substances taken from the literature. Therefore, we synthesized four different MgSO4 hydrates and measured their enthalpies of formation by solution calorimetry at T = 298.15 K. The resulting enthalpies of formation from the elements are:
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- ΔfH0298 (epsomite) = −3387.7 ± 1.3 kJmol−1
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- ΔfH0298 (hexahydrite) = −3088.1 ± 1.1 kJmol−1
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- ΔfH0298 (sanderite, MgSO4·2H2O) = −1894.9 ± 1.3 kJmol−1
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- ΔfH0298 (kieserite) = −1612.4 ± 1.3 kJmol−1
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- Epsomite: ΔfH0298 = −3388.7 kJmol−1, S0298 = 371.3 Jmol−1 K−1, ΔfG0298 = −2871.0 kJmol−1
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- Hexahydrite: ΔfH0298 = −3087.3 kJmol−1, S0298 = 348.5 Jmol−1 K−1, ΔfG0298 = −2632.3 kJmol−1
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- Starkeyite: ΔfH0298 = −2496.1 kJmol−1, S0298 = 259.9 Jmol−1 K−1, ΔfG0298 = −2153.8 kJmol−1
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- Kieserite: ΔfH0298 = −1611.5 kJmol−1, S0298 = 126.0 Jmol−1 K−1, ΔfG0298 = −1437.9 kJmol−1
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Quantitative relations of seismic source parameters and a classification of earthquakes 总被引:1,自引:0,他引:1
G Purcaru 《Tectonophysics》1982,84(1):57-128
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