Gibbsite

Formula : Al(OH)3

Family: 
Hydroxides
Space group: 
Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 21/n
Dana class: 
6.3.1.1 (6)Hydroxides and Oxides Containing Hydroxyl (6.3) with (OH)3 or (OH)6 groups (6.3.1) Dana Group
High temperature: 
Stable at room temperature.
Geological context: 
Mineral common in lateritic soils developed on aluminous rocks in areas of high rainfall, but also common in aluminum-bearing byproducts from thermic processes.

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
 V°
cm3·mol-1
 ΔGºf
J·mol-1
 ΔHºf
J·mol-1
 Sº
J·mol-1·k-1
 CP
J·mol-1·K-1
78.004 31.956 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. -1154909 (Ref.: 95pok/hel) Pokrovskii, V.A., and Helgeson, H.C., 1995, Thermodynamic properties of aqueous species and the solubilities of minerals at high pressures and temperatures: The system Al2O3-H2O-NaCl: Amer. J. Sci., 295, 1255-1342. -1293131 (Ref.: Internal calculation) 68.450 (Ref.: 95pok/hel) Pokrovskii, V.A., and Helgeson, H.C., 1995, Thermodynamic properties of aqueous species and the solubilities of minerals at high pressures and temperatures: The system Al2O3-H2O-NaCl: Amer. J. Sci., 295, 1255-1342. 91.72 (Ref.: 95pok/hel) Pokrovskii, V.A., and Helgeson, H.C., 1995, Thermodynamic properties of aqueous species and the solubilities of minerals at high pressures and temperatures: The system Al2O3-H2O-NaCl: Amer. J. Sci., 295, 1255-1342.
CP(T) = a + b·T + ·c·T-2 (T in Kelvin)
a
J·mol-1·K-1
 b * 103
J·mol-1·K-2
 c * 10-5
J·K·mol-1
 Maier Kelley Ref.
54.70 170.27 -12.22 (Ref.: 95pok/hel) Pokrovskii, V.A., and Helgeson, H.C., 1995, Thermodynamic properties of aqueous species and the solubilities of minerals at high pressures and temperatures: The system Al2O3-H2O-NaCl: Amer. J. Sci., 295, 1255-1342.
Reaction properties

Gibbsite + 3H+ ⇌ Al+3 + 3H2O

298.15 K, 1 bar log10K: 7.74 ΔH°r:-102759 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 9.39 7.74 5.85 4.13 2.42 1.00 -0.25 -1.43
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-493.750369 -0.080900 29713.753509 177.902703 -1267653.317951