Sodium sulfate heptahydrate: Difference between revisions

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==The importance of the heptahydrate in the damage process==
==The importance of the heptahydrate in the damage process==


For more informations see <bib id="Saidov:201"/>
For more informations see <bib id="Saidov:2012"/>


==Weblinks==
==Weblinks==

Latest revision as of 08:27, 12 April 2023

Author: Amelie Stahlbuhk
back to Sulfate


Sodium sulfate heptahydrate
Mineralogical name
Chemical name sodium sulfate heptahydrate
Trivial name
Chemical formula Na2SO4•7H2O
Other forms Na2SO4•10H2O (Mirabilite)
Crystal system
Crystal structure
Deliquescence humidity 20°C 89.1 %
Solubility (g/l) at 20°C 3.143 mol/kg
Density (g/cm³)
Molar volume
Molar weight 268,14 g/mol
Transparency
Cleavage
Crystal habit
Twinning
Phase transition
Chemical behavior
Comments
Crystal Optics
Refractive Indices
Birefringence
Optical Orientation
Pleochroism
Dispersion
Used Literature
[Steiger.etal:2008]Title: Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress
Author: Steiger, Michael; Asmussen, Sönke
Link to Google Scholar


Introduction[edit]

Sodium sulfate heptahydrate is a metastable phase of sodium sulfate. Its formation can be observed during the rapid cooling of a solution that is saturated at 40 °C [Gans:1978]Title: Thermodynamic stability of sodium sulfate heptahydrate
Author: Gans, W.
Link to Google Scholar

Solubility[edit]

Figure 1: Solubility of Na2SO4 in water, according to : [Steiger.etal:2008]Title: Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress
Author: Steiger, Michael; Asmussen, Sönke
Link to Google Scholar



The solubility of the heptahydrate at 20 °C is 3.145 mol/kg [Steiger.etal:2008]Title: Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress
Author: Steiger, Michael; Asmussen, Sönke
Link to Google Scholar
. Figure 1 indicates that, eventhough it is a metastable phase, the heptahydrate is more relevant at lower temperatures.

Hygroscopicity[edit]


Figure 2:Deliquescence of Na2SO4, according to: [Steiger.etal:2008]Title: Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress
Author: Steiger, Michael; Asmussen, Sönke
Link to Google Scholar


At 20 °C the deliquescence humidity lies at 89.1 %. The values are higher at lower temperatures (table 1).


Table 1: Deliquescnece humidity of sodium sulfate heptahydrate at different round temperatures, according to [Steiger.etal:2008]Title: Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress
Author: Steiger, Michael; Asmussen, Sönke
Link to Google Scholar
0°C 10°C 20°C
96.1%r.h. 93.3%r.h. 89.1%r.h.


The importance of the heptahydrate in the damage process[edit]

For more informations see [Saidov:2012]Title: Sodium sulfate heptahydrate in weathering phenomena of porous materials
Author: Saidov, Tamerlan Adamovich
Link to Google Scholar

Weblinks[edit]


Literature[edit]

[Gans:1978]Gans, W. (1978): Thermodynamic stability of sodium sulfate heptahydrate. In: Zeitschrift für Physikalische Chemie, 111 (1), 39-46, UrlLink to Google Scholar
[Saidov:2012]Saidov, Tamerlan Adamovich (2012): Sodium sulfate heptahydrate in weathering phenomena of porous materials. dissertation, Technische Universiteit Eindhoven, UrlLink to Google Scholar
[Steiger.etal:2008]Steiger, Michael; Asmussen, Sönke (2008): Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress. In: Geochimica et Cosmochimica Acta, 72 (17), 4291-4306, UrlLink to Google Scholar