TY - JOUR
T1 - Thermodynamics of monoclinic Fe2(SO4)3
AU - Majzlan, Juraj
AU - Navrotsky, Alexandra
AU - Stevens, Rebecca
AU - Donaldson, Marcus
AU - Woodfield, Brian F.
AU - Boerio-Goates, Juliana
N1 - Funding Information:
We thank an anonymous reviewer for helpful comments and M. Trusler for editorial handling of the manuscript. J.M. thanks for the support that came from the Hess post-doctoral fellowship at the Department of Geosciences at Princeton University. R.S. thanks BYU Office of Research and Creative Works for partial support. We thank M. Borcsik (Princeton Univ) for help with the ICP-OES analysis. The synthesis and calorimetry at UC Davis was supported by the U.S. Department of Energy (Grant DE FG03 97 ER14749).
PY - 2005/8
Y1 - 2005/8
N2 - Thermodynamic properties of monoclinic Fe2(SO4) 3 were measured by acid solution calorimetry, adiabatic calorimetry, and semi-adiabatic calorimetry. The standard molar enthalpy of formation ΔfHm° was determined as -(2585.2 ± 4.9) kJ • mol -1 by an appropriate thermochemical cycle with enthalpies of solution of monoclinic Fe2(SO4)3, α-MgSO 4, γ-FeOOH, H2O, and MgO in 5 N HCl at T = 298 K. Heat capacity data were collected from T = (0.5 to 400) K. The standard molar entropy Sm° at T = 298.15 K is (305.6 ± 0.6) J • K-1 • mol-1. While the enthalpy of formation agrees well with a previous ΔfHm° determination, the entropy differs significantly because magnetic entropy was entirely overlooked in the previous work. The heat capacity shows a sharp magnetic transition with the peak located at 30.0 K. The Cp,m data in the temperature range (273 to 395) K are represented by a Maier-Kelley polynomial Cp,m/J • K-1 • mol-1 = 213.0 + 0.3121(T/K) - 2.959 × 106(T/K) -2. The calculated standard molar Gibbs free energy of formation from the elements ΔfGm° at T = 298.15 K is -(2264.5 ± 4.9) kJ • mol-1.
AB - Thermodynamic properties of monoclinic Fe2(SO4) 3 were measured by acid solution calorimetry, adiabatic calorimetry, and semi-adiabatic calorimetry. The standard molar enthalpy of formation ΔfHm° was determined as -(2585.2 ± 4.9) kJ • mol -1 by an appropriate thermochemical cycle with enthalpies of solution of monoclinic Fe2(SO4)3, α-MgSO 4, γ-FeOOH, H2O, and MgO in 5 N HCl at T = 298 K. Heat capacity data were collected from T = (0.5 to 400) K. The standard molar entropy Sm° at T = 298.15 K is (305.6 ± 0.6) J • K-1 • mol-1. While the enthalpy of formation agrees well with a previous ΔfHm° determination, the entropy differs significantly because magnetic entropy was entirely overlooked in the previous work. The heat capacity shows a sharp magnetic transition with the peak located at 30.0 K. The Cp,m data in the temperature range (273 to 395) K are represented by a Maier-Kelley polynomial Cp,m/J • K-1 • mol-1 = 213.0 + 0.3121(T/K) - 2.959 × 106(T/K) -2. The calculated standard molar Gibbs free energy of formation from the elements ΔfGm° at T = 298.15 K is -(2264.5 ± 4.9) kJ • mol-1.
KW - Entropy
KW - Heat capacity
KW - Heat of formation
KW - Magnetic transition
KW - Monoclinic iron(III) sulfate
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U2 - 10.1016/j.jct.2004.11.021
DO - 10.1016/j.jct.2004.11.021
M3 - Article
AN - SCOPUS:20444442018
SN - 0021-9614
VL - 37
SP - 802
EP - 809
JO - Journal of Chemical Thermodynamics
JF - Journal of Chemical Thermodynamics
IS - 8
ER -