Amorphous_silica

Formula : SiO2

High temperature: 
The stability of amorphous silica (opal) is limited to the low temperature springs <150C.
Geological context: 
In the hydrothermal systems.

Dernière mise à jour le 11.06.2018

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
cm3·mol-1
ΔGºf
J·mol-1
ΔHºf
J·mol-1
J·mol-1·k-1
CP
J·mol-1·K-1
60.084 29.000 -850359 -903150 46.900 59.89
Reaction properties

Amorphous_silica + 2H2O ⇌ H4SiO4

298.15 K, 1 bar log10K: -2.70 ΔH°r: 13616 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K -2.92 -2.70 -2.45 -2.22 -2.00 -1.82 -1.67 -1.54