Bischofite: Difference between revisions

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{{Infobox_Salt
{{Infobox_Salt
|Footnote            = <ref> http://webmineral.com/data/Bischofite.shtml  viewed on 29/07/2010</ref><ref> http://www.mindat.org/min-681.html  viewed on 29/07/2010</ref>
|Footnote            = <ref> http://webmineral.com/data/Bischofite.shtml  viewed on 29/07/2010</ref><ref> http://www.mindat.org/min-681.html  viewed on 29/07/2010</ref>  
|photo                = <!-- [[Image:"file name"|300px]]-->
|photo                = <!-- [[Image:"file name"|300px]]-->
|mineralogical_Name  = Bischofite
|mineralogical_Name  = Bischofite
|chemical_Name        = Magnesiumchloride hexahydrate
|chemical_Name        = Magnesium chloride hexahydrate
|Trivial_Name        =
|Trivial_Name        =
|chemical_Formula      =MgCl<sub>2</sub>•6H<sub>2</sub>O
|chemical_Formula      =MgCl<sub>2</sub>•6H<sub>2</sub>O
|Hydratforms          =
|Hydratforms          =
|Crystal_Class        =monoclinic
|Crystal_System      =monoclinic
|Deliqueszenzhumidity =
|Crystal_Structure =
|Solubility          =
|Deliqueszenzhumidity =33.1%
|Density              =1,56 g/cm<sup>3</sup>
|Solubility          =5.75 mol/kg
|MolVolume            =129,6 cm<sup>3</sup>/mol
|Density              =1.57 g/cm<sup>3</sup>
|Molweight            =203,33 g/mol
|MolVolume            =129.6 cm<sup>3</sup>/mol
|Molweight            =203.30 g/mol
|Transparency        =transparent to translucent
|Transparency        =transparent to translucent
|Cleavage            =none
|Cleavage            =none
|Crystal_Habit        =
|Crystal_Habit        =
|Twinning            =
|Twinning            =
|Refractive_Indices  =n<sub>x</sub> =1,494<br> n<sub>y</sub> = 1,507<br> n<sub>z</sub> = 1,528
|Refractive_Indices  =n<sub>x</sub> =1.495<br> n<sub>y</sub> = 1.509<br> n<sub>z</sub> = 1.528
|Birefringence        =Δ = 0,034
|Birefringence        =Δ = 0.003
|optical_Orientation  =positive
|optical_Orientation  =positive
|Pleochroism          =
|Pleochroism          =
|Dispersion          =
|Dispersion          =79°
|Phase_Transition    =
|Phase_Transition    =
|chemBehavior        =
|chemBehavior        =
|Comments            =
|Comments            =decomposes at 116-118°C<br>hygroscopic and deliquescent
|Literature = <bib id="Broul.etal:1981"/> <bib id="Dana:1951"/> <bib id="Steiger.etal:2011a"/>
}}
}}


back to [[Chloride]]
 
 
==Solubility==
Bischofite has got a high solubility in water (5.75 mol/kg at 20 °C). The solubility of bischofite and other phases of the system MgCl<sub>2</sub>-H<sub>2</sub>O is shown in Fig. 1. <br>
 
[[Image:MgCl2 S.jpg|thumb|left|800px|Figure 1: Solubility of magnesium chloride in water. The molality ''m'' [n(MgCl<sub>2</sub>)•kg(H<sub>2</sub>O)<sup>-1</sup>] is plotted versus the temperature.]]
<br clear=all>
 
==Hygroscopicity==
Figure 2 includes the phase diagram of the system MgCl<sub>2</sub>-H<sub>2</sub>O. Next to the hexahydrate bischofite there are two more stable phases within the regarded temperature range. The octa- and the dodecahydrate are relevant at lower temperatures. <br>
 
[[Image:D MgCl2 e.jpg|thumb|left|800px|Figure 2: Phase diagram of the system MgCl<sub>2</sub>-H<sub>2</sub>O.The water activity ''a<sub>w</sub> is plotted versus the temperature.]]  
 
<br clear="all">
 
<br clear=all>
{|border="2" cellspacing="0" cellpadding="4" width="52%" align="left" class="wikitable"
|+''Table 1: Deliquescence humidities of bischofite at different temperatures <bib id="Steiger.etal:2014"/>''                   
|-
|bgcolor = "#F0F0F0" align=center| 0°C
|bgcolor = "#F0F0F0" align=center| 10°C
|bgcolor = "#F0F0F0" align=center| 20°C
|bgcolor = "#F0F0F0" align=center| 30°C
|bgcolor = "#F0F0F0" align=center| 40°C
|bgcolor = "#F0F0F0" align=center| 50°C
|-
|bgcolor = "#FFFFEO" align=center| 34.1%r.h.
|bgcolor = "#FFFFEO" align=center| 33.7%r.h.
|bgcolor = "#FFFFEO" align=center| 33.1%r.h.
|bgcolor = "#FFFFEO" align=center| 32.4%r.h.
|bgcolor = "#FFFFEO" align=center| 31.5%r.h.
|bgcolor = "#FFFFEO" align=center| 30.5%r.h.
|}
<br clear=all>


==Weblinks==
==Weblinks==
<references/>
<references/>


[[Category:Bischofite]][[Category:Chloride]][[Category:Salt]][[Category:InProgress]]
== Literature==
 
<biblist/>
 
 
[[Category:Bischofite]][[Category:Chloride]][[Category:Salt]][[Category:InProgress]][[Category:List]]

Latest revision as of 11:32, 3 May 2023

back to Chloride

Bischofite[1][2]
Mineralogical name Bischofite
Chemical name Magnesium chloride hexahydrate
Trivial name
Chemical formula MgCl2•6H2O
Other forms
Crystal system monoclinic
Crystal structure
Deliquescence humidity 20°C 33.1%
Solubility (g/l) at 20°C 5.75 mol/kg
Density (g/cm³) 1.57 g/cm3
Molar volume 129.6 cm3/mol
Molar weight 203.30 g/mol
Transparency transparent to translucent
Cleavage none
Crystal habit
Twinning
Phase transition
Chemical behavior
Comments decomposes at 116-118°C
hygroscopic and deliquescent
Crystal Optics
Refractive Indices nx =1.495
ny = 1.509
nz = 1.528
Birefringence Δ = 0.003
Optical Orientation positive
Pleochroism
Dispersion 79°
Used Literature
[Broul.etal:1981]Title: Solubility in organic two component systems
Author: Broul M., Nyvlt J.; Soehnel O.
Link to Google Scholar [Dana:1951]Title: Dana's System of Mineralogy
Author: Dana J.D.
Link to Google Scholar [Steiger.etal:2011a]Title: Decomposition reactions of magnesium sulfate hydrates and phase equilibria in the MgSO4-H2O and Na+-Mg2+-Cl--SO42--H2O systems with implications for Mars
Author: Steiger, Michael; Linnow, Kirsten; Ehrhardt, Dorothee; Rohde, Mandy
Link to Google Scholar



Solubility[edit]

Bischofite has got a high solubility in water (5.75 mol/kg at 20 °C). The solubility of bischofite and other phases of the system MgCl2-H2O is shown in Fig. 1.

Figure 1: Solubility of magnesium chloride in water. The molality m [n(MgCl2)•kg(H2O)-1] is plotted versus the temperature.


Hygroscopicity[edit]

Figure 2 includes the phase diagram of the system MgCl2-H2O. Next to the hexahydrate bischofite there are two more stable phases within the regarded temperature range. The octa- and the dodecahydrate are relevant at lower temperatures.

Figure 2: Phase diagram of the system MgCl2-H2O.The water activity aw is plotted versus the temperature.



Table 1: Deliquescence humidities of bischofite at different temperatures [Steiger.etal:2014]Title: Weathering and Deterioration
Author: Steiger, Michael; Charola A. Elena; Sterflinger, Katja
Link to Google Scholar
0°C 10°C 20°C 30°C 40°C 50°C
34.1%r.h. 33.7%r.h. 33.1%r.h. 32.4%r.h. 31.5%r.h. 30.5%r.h.


Weblinks[edit]

  1. ↑ http://webmineral.com/data/Bischofite.shtml viewed on 29/07/2010
  2. ↑ http://www.mindat.org/min-681.html viewed on 29/07/2010

Literature[edit]

[Broul.etal:1981]Elsevier (eds.) Broul M., Nyvlt J.; Soehnel O. (1981): Solubility in organic two component systems, ElsevierLink to Google Scholar
[Dana:1951]Dana E.S. (eds.) Dana J.D. (1951): Dana's System of Mineralogy, 7, Wiley & SonsLink to Google Scholar
[Steiger.etal:2011a]Steiger, Michael; Linnow, Kirsten; Ehrhardt, Dorothee; Rohde, Mandy (2011): Decomposition reactions of magnesium sulfate hydrates and phase equilibria in the MgSO4-H2O and Na+-Mg2+-Cl--SO42--H2O systems with implications for Mars. In: Geochimica et Cosmochimica Act, 75 (12), 3600-3626, 10.1016/j.gca.2011.03.038,Link to Google Scholar
[Steiger.etal:2014]Steiger, Michael; Charola A. Elena; Sterflinger, Katja (2014): Weathering and Deterioration. In: Siegesmund S.; Snethlage R. (eds.): Stone in Architecture, Springer Verlag Berlin Heidelberg, 223-316, 10.1007/978-3-642-45155-3_4.Link to Google Scholar

A phase is a physically distinctive form of matter and is characterized by having relatively uniform chemical and physical properties.

concentration given as amount of substance (mol) of the dissolved substance per kilogram solvent; unit: mol•kg-1.

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