Wairakite

Formula : Ca(Al2Si4)O12:2H2O

Family: 
Zeolites
Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: I2/a
Dana class: 
77.1.1.3VIII- 77 Tektosilicates Tectosilicate Zeolite group ; 77.1 Tektosilicates Tectosilicate Zeolite group true zeolites ; 77.1.1 Analcime and related species
High temperature: 
See Laumontite
Geological context: 
low temperature alteration of volcanics, geothermal field

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
434.406 193.560 (Ref.: 97coo/alb) Coombs, D.S., Alberti, A., Armbruster, T., Artioli, G., Colella, C., Galli, E., Grice, J.D., Liebau, F., Mandarino, J.A., Minato, H., Nickel, E.H., Passaglia, E., Peacor, D.R., Quartieri, S., Rinaldi, R., Ross, M., Sheppard, R.A., Tillmanns, E., Vealini, G., 1997. Recommended nomenclature for zeolite minerals - report of the subcommittee on zeolites of the international mineralogical association, commission on new minerals and mineral names. Canadian Mineralogist, 35, 1571-1606. -6208374 (Ref.: Internal calculation) -6646700 (Ref.: 96kis/nav) Kiseleva I., Navrotsky A., Belitskii I. A., and Fursenko B. A. (1996) Thermochemistry and phase equilibria in calcium zeolites. American Mineralogist 81(5-6), 658-667 400.700 (Ref.: 96kis/nav) Kiseleva I., Navrotsky A., Belitskii I. A., and Fursenko B. A. (1996) Thermochemistry and phase equilibria in calcium zeolites. American Mineralogist 81(5-6), 658-667 401.04 (Ref.: 07neu/wan) Neuhoff P. S. and Wang J. (2007) Heat capacity of hydration. American Mineralogist 92, 1358-1367
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.
255.39 577.40 -23.56 (Ref.: 07neu/wan) Neuhoff P. S. and Wang J. (2007) Heat capacity of hydration. American Mineralogist 92, 1358-1367
Reaction properties

Wairakite + 8H+ + 2H2O ⇌ 2Al+3 + Ca+2 + 4H4SiO4

298.15 K, 1 bar log10K: 14.44 ΔH°r:-236884 J·mol-1 (Ref.: 96kis/nav) Kiseleva I., Navrotsky A., Belitskii I. A., and Fursenko B. A. (1996) Thermochemistry and phase equilibria in calcium zeolites. American Mineralogist 81(5-6), 658-667
T(°C) 0 25 60 100 150 200 250 300
log10K 18.07 14.44 9.96 5.73 1.44 -2.12 -5.29 -8.33
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-2659.569040 -0.372060 166521.322693 943.882615 -9702554.574925