Thermonatrite: Difference between revisions
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English version by [[user:SLeithaeuser|Sandra Leithäuser]] | English version by [[user:SLeithaeuser|Sandra Leithäuser]] | ||
back to [[Carbonate]] | |||
{{Infobox_Salt | {{Infobox_Salt | ||
|Footnote =<ref>http://webmineral.com/data/Thermonatrite.shtml viewed on 09/06/2011</ref><ref>http://www.mindat.org/min-3938.html viewed on 09/06/2011</ref> | |Footnote =<ref>http://webmineral.com/data/Thermonatrite.shtml viewed on 09/06/2011</ref><ref>http://www.mindat.org/min-3938.html viewed on 09/06/2011</ref> | ||
|photo = <!--[[Image:"file name"|300px]]--> | |photo = <!--[[Image:"file name"|300px]]--> | ||
|mineralogical_Name =Thermonatrite | |mineralogical_Name =Thermonatrite | ||
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|Deliqueszenzhumidity =71% (35°C) | |Deliqueszenzhumidity =71% (35°C) | ||
|Solubility =330 g/l | |Solubility =330 g/l | ||
|Density =2. | |Density =2.250 g/cm<sup>3</sup> | ||
|MolVolume =55.11 cm<sup>3</sup>/mol | |MolVolume =55.11 cm<sup>3</sup>/mol | ||
|Molweight =124. | |Molweight =124.00 g/mol | ||
|Transparency =transparent | |Transparency =transparent | ||
|Cleavage =poor to indistinct | |Cleavage =poor to indistinct | ||
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|chemBehavior = | |chemBehavior = | ||
|Comments =alkaline in aqueous solution<br>pH about 12 | |Comments =alkaline in aqueous solution<br>pH about 12 | ||
|Literature = <bib id="Lide:1995"/> | |||
}} | }} | ||
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<br> '''Examination with the polarization microscope:'''<br> | <br> '''Examination with the polarization microscope:'''<br> | ||
As a function of the prevailing relative humidity and temperature conditions, the crystals of the starting sample material and the re-crystallized specimen change in the amount of chemically bound water. In dry air (< ca. 60% RH) predominantly thermonatrite will be present after a short time.<br>The assignment of the refractive indices of thermonatrite is carried out according to the immersion method. Single particles that have been embedded in standard immersion oil with a refractive index of n<sub>D</sub> = 1,518, show strong relief changes on rotation under polarized transmitted light <bib id="Blaeuer-Boehm:1994"/>, a.a.O., S. 86 ff. Due to high birefringence, thermonatrite crystals have lively interference colors. These are a clear differentiating factor from natrite, having a much lower maximum birefringence. <br> Thermonatrite belongs to the orthorhombic crystal order. This association is connected with the occurrence of parallel and/or symmetrical extinction. Large crystal needles are usually completely extinct. The extinction occurs '''sharply??'''. | As a function of the prevailing relative humidity and temperature conditions, the crystals of the starting sample material and the re-crystallized specimen change in the amount of chemically bound water. In dry air (< ca. 60% RH) predominantly thermonatrite will be present after a short time.<br>The assignment of the refractive indices of thermonatrite is carried out according to the immersion method. Single particles that have been embedded in standard immersion oil with a refractive index of n<sub>D</sub> = 1,518, show strong relief changes on rotation under polarized transmitted light <bib id="Blaeuer-Boehm:1994"/>, a.a.O., S. 86 ff. Due to high birefringence, thermonatrite crystals have lively interference colors. These are a clear differentiating factor from natrite, having a much lower maximum birefringence. <br> Thermonatrite belongs to the orthorhombic crystal order. This association is connected with the occurrence of parallel and/or symmetrical extinction. Large crystal needles are usually completely extinct. <!--The extinction occurs '''sharply??'''.--> | ||
<br> '''Please check:''' | <br> '''Please check:''' | ||
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== Weblinks == | == Weblinks == | ||
<references/ | <references/> | ||
== Literatur == | == Literatur == | ||
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[[Category:Thermonatrite]][[Category:Carbonate]][[Category:Salt]][[Category:InProgress]] | [[Category:Thermonatrite]][[Category:Carbonate]][[Category:Salt]][[Category:InProgress]] | ||
[[Category:List]] | |||
Latest revision as of 17:42, 15 February 2015
Authors: Hans-Jürgen Schwarz, Nils Mainusch
English version by Sandra Leithäuser
back to Carbonate
| Thermonatrite[1][2] | |
| Mineralogical name | Thermonatrite |
| Chemical name | Sodium carbonate hydrate |
| Trivial name | Sodium carbonate |
| Chemical formula | Na2CO3•H2O |
| Other forms | Natrite (Na2CO3) Sodium carbonate heptahydrate (Na2CO3•7H2O) Sodium carbonate decahydrate (Na2CO3•10H2O) |
| Crystal system | orthorhombic |
| Crystal structure | |
| Deliquescence humidity 20°C | 71% (35°C) |
| Solubility (g/l) at 20°C | 330 g/l |
| Density (g/cm³) | 2.250 g/cm3 |
| Molar volume | 55.11 cm3/mol |
| Molar weight | 124.00 g/mol |
| Transparency | transparent |
| Cleavage | poor to indistinct |
| Crystal habit | |
| Twinning | |
| Phase transition | |
| Chemical behavior | |
| Comments | alkaline in aqueous solution pH about 12 |
| Crystal Optics | |
| Refractive Indices | nx = 1.420 ny= 1.509 nz = 1.525 |
| Birefringence | Δ = 0.105 |
| Optical Orientation | biaxial negative |
| Pleochroism | |
| Dispersion | |
| Used Literature | |
| [Lide:1995]Title: CRC Handbook of Chemistry and Physics Author: Lide D.R. 
| |
N.B.[edit]
General information on transition reaction, hydrate pressures and occurrence are available on Sodium carbonate – natrite.
Hygroscopicity[edit]
Estimating the hygroscopicity of sodium carbonates in situ is difficult, because the sorption point and saturation values vary greatly as a function of the local environment (i.e., foreign ions, hydrate stages present, temperature conditions). In the following section, values for the deliquescence humidity of thermonatrite and natrite as a function of the ambient air temperature are listed (see also table Gleichgewichtsfeuchte in Abhängigkeit von Temperatur):
| 35°C |
| 71.0% RH |
| 15°C | 20°C | 25°C | 30°C |
| 96.5% RH | 97.9% RH | 88.2% RH | 83.2% RH |
Analytical detection[edit]
The identification of thermonatrite and natrite can be carried out in situ by dissolution in water and measuring the resultant pH: According to Bläuer/ Böhm, natrite is the only efflorescent salt known to date, that is alkaline (pH clearly greater than 8) and has the property to dissolve in its chemically bound water at slight warming. The solubility in water is good. Thermonatrite is not soluble in anhydrous ethanol.
Microscopy
[edit]
Laboratory investigation:
Good solubility in water and low solubility in ethanol can be checked using microscopy. Thermonatrite and natrite
have a marked tendency towards the formation of acicular or dendritic crystal shapes when re-crystallizing. If gypsum is present in the sample material, a rapid precipitation of calcium carbonate takes place, which becomes apparent through a whitish precipitate.
Refractive indices: nx = 1.420; ny = 1.509; nz = 1,525;
Birefringence: Δ = max. 0,105
Crystal classe: orthorhombic
Examination with the polarization microscope:
As a function of the prevailing relative humidity and temperature conditions, the crystals of the starting sample material and the re-crystallized specimen change in the amount of chemically bound water. In dry air (< ca. 60% RH) predominantly thermonatrite will be present after a short time.
The assignment of the refractive indices of thermonatrite is carried out according to the immersion method. Single particles that have been embedded in standard immersion oil with a refractive index of nD = 1,518, show strong relief changes on rotation under polarized transmitted light [Blaeuer-Boehm:1994]Title: Salzuntersuchungen an Baudenkmälern
Author: Bläuer-Böhm, Christine, a.a.O., S. 86 ff. Due to high birefringence, thermonatrite crystals have lively interference colors. These are a clear differentiating factor from natrite, having a much lower maximum birefringence.
Thermonatrite belongs to the orthorhombic crystal order. This association is connected with the occurrence of parallel and/or symmetrical extinction. Large crystal needles are usually completely extinct.
Please check:
Thermonatrite is clearly assignable, if the following examination criteria have been clarified.
- high pH-value
- good solubility in water
- characteristic habit
- all refractive indices below nD=1,53
- high birefringence
- parallel/symmetrical extinction
| Salt phase | Distinguishing features to thermonatrite |
| Nesquehonite MgCO3 • 3H2O; | slightly water soluble/ oblique extinction |
| Lansfordite MgCO3 • 5H2O | slightly water soluble / oblique extinction / low birefringence |
| Trona Na3H(CO3)2 • 2H2O | mainly observed index > 1,53 / oblique extinction |
| Potash K2CO3 | mainly observed index > 1,53 / oblique extinction / strongly hygroscopic |
Weblinks[edit]
- ↑ http://webmineral.com/data/Thermonatrite.shtml viewed on 09/06/2011
- ↑ http://www.mindat.org/min-3938.html viewed on 09/06/2011
Literatur[edit]
| [Blaeuer-Boehm:1994] | Bläuer-Böhm, Christine (1994): Salzuntersuchungen an Baudenkmälern. In: Zeitschrift für Kunsttechnologie und Konservierung, 8 (1), 86-103 | |
| [Lide:1995] | Lide D.R. (eds.) Lide D.R. (1995): CRC Handbook of Chemistry and Physics, CRC Press | |