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Author: [[Benutzer:Hschwarz|Hans-Jürgen Schwarz]]
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back to [[Polarized light microscopy]] or [[Analysis of Salts]]
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== Abstract  ==
This section describes the determination of salts using [[polarized light microscopy]].
== Method ==
The examination of salts can be carried out using several different methods, the present article focuses on two different approaches to the microscopic analysis of salts.
The first method is based on the examination of the salts, i.e., salt crystals as taken from the object.
The second method analyses the salt as it re-crystallizes from an aqueous solution of the sample. The salt crystallization obtained from solution may vary from that present in the original sample, depending on the different kinds of salt present as described below. Please see also [[Micro-chemical testing]].
It is important to remember that in conventional chemical analysis, testing the presence of the carbonate anion is not carried out routinely, so that its presence may be overlooked, although they are often found in building materials and may cause their deterioration.
== Determination of single salts in aqueous extract ==
The sample to be examined (pure salt or material/salt mixture) is mixed with a few drops of distilled water, producing an aqueous [[Micro-chemical testing#Test methods|salt solution with reference to Bläuer]]. A few drops of this solution are placed onto a microscope slide and observed under the polarizing microscope. It is important to observe the crystallization of the salts from the beginning, i.e., from the appearance of the first small crystals until the end of the crystallization process, because salts that crystallize later may cover up some of the initial salt crystals completely. Therefore, if not identified at the beginning, their presence may become difficult, if not impossible to see. The continuous documentation of the process is therefore important for an accurate analysis. Only then, the right conclusions can be drawn.
== Halite (NaCl) ==
Figures 1-3 show halite crystals. Halite and sylvite (KCl) are the only isotropic salt crystals, i.e., belonging to the cubic crystal system. Conversely, this does not mean that all crystals that appear isotropic on the microscope slide are cubic, some salts crystallize at an orientation that makes them optically isotropic in appearance only. Therefore caution is vital. In comparison with typical cubic crystal shapes, however, the identification is unambiguous.
<dpl>
category = Halite&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption="Halite, crystallized from aqueous solution on a microscope slide" widths="200px" heights="150px" perrow="3">
Image:NaCl_27.4.2006-10x_(1).JPG|Figure 1: Halite crystals under polarized light
Image:NaCl_27.4.2006-10x_(2).JPG|Figure 2: Halite crystals under polarized light with analyzer
Image:NaCl_27.4.2006-10x_(6).JPG|Figure 3: Halite crystals under polarized light with analyzer and red I
</gallery>
== Calcium chloride ==
Calcium chloride only crystallizes at relatively low relative humidity levels (pure salts at a RH <30, 8% and 20°C). Because the relative humidity on objects and in the laboratory usually lies above this value, the crystalline form of calcium chloride can only rarely be seen on an object. It is possible to observe the crystals under the polarizing microscope, by warming up the slide until they form. However, the crystals dissolve in the ambient air when the temperature cools down and the RH rises. Figures 4- 6 show calcium chloride crystals while warming.
<dpl>
category = Antarcticite&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption="Calcium chloride, crystallized from aqueous solution on a microscope slide " widths="200px" heights="150px" perrow="3">
Image:HJS_Ca%28Cl%292_100903-10-7.jpg|Abbildung 4: Calcium chloride crystals under polarized light
Image:HJS_Ca%28Cl%292_100903-10-6.jpg|Abbildung 5: Calcium chloride crystals under polarized light with analyzer
Image:HJS_Ca%28Cl%292_100903-10-1.jpg|Abbildung 6: Calcium chloride crystals under polarized light with analyzer and red I
</gallery>
== Niter ==
<dpl>
category = Niter&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,Chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption="Niter crystallized from aqueous solution on a microscope slide" widths="200px" heights="150px" perrow="3">
Image:HJS_KNO3_092503-6.jpg|Figure 7:Potassium nitrate crystals under polarized light
Image:HJS_KNO3_092503-5.jpg| Figure 8: Potassium nitrate crystals under polarized light with analyzer
Image:HJS_KNO3_092503-4.jpg| Figure 9: Potassium nitrate crystals under polarized light with analyzer and red I
</gallery>
== Calcium nitrate ==
<dpl>
category = Nitrocalcite&Salt
include ={Infobox_Salz}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,Chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption="Calcium nitrate crystallized from aqueous solution on a microscope slide " widths="200px" heights="150px" perrow="3">
Image:HJS_Ca%28NO3%292_101703-4-6.jpg| Figure 10:Calcium nitrate crystals under polarized light
Image:HJS_Ca%28NO3%292_101703-4-5.jpg| Figure 11:Calcium nitrate crystals under polarized light with analyzer
Image:HJS_Ca%28NO3%292_101703-4-4.jpg| Figure 12:Calcium nitrate crystals under polarized light with analyzer and red I
</gallery>
== Magnesium nitrate ==
<dpl>
category = Nitromagnesite&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,Chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption="Magnesium nitrate crystallized from aqueous solution on a microscope slide" widths="200px" heights="150px" perrow="3">
Image:MgNO3-2_%283%29-klein.jpg|Abbildung 13:Magnesium nitrate crystals under polarized light
Image:| crystals under polarized light with analyzer
Image:Mg-NO3-2_%281%29.jpg Figure 14:Magnesium nitrate kristalle unter polarisiertem Licht mit Analysator und Rot I
</gallery>
== Gypsum ==
<dpl>
category = Gipsum&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption=" Gypsum crystallized from aqueous solution on a microscope slide " widths="200px" heights="150px" perrow="3">
Image:NaCl_%2BGips_9.5.2006_(9).jpg| Figure 15:Calcium sulfate crystals under polarized light
Image:NaCl_%2BGips_9.5.2006_(8).jpg| Figure 16:Calcium crystals under polarized light with analyzer
Image:NaCl_%2BGips_9.5.2006_(7).jpg| Figure 17:Calcium sulfate crystals under polarized light with analyzer and red I
</gallery>
== Magnesium sulfate ==
<dpl>
category = Epsomite&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption="Magnesium sulfate crystallized from aqueous solution on a microscope slide" widths="200px" heights="150px" perrow="3">
Image:MgSO4_29-5-2010_17.JPG| Figure 18:Magnesium sulfate crystals under polarized light
Image:MgSO4_29-5-2010_16.JPG| Figure 19:Magnesium sulfate crystals under polarized light with analyzer
Image:MgSO4_29-5-2010_(15).JPG| Figure 20:Magnesium sulfate crystals under polarized light with analyzer and red I
Image:HJS_MgSO4_092503-5.jpg| Figure 21:Magnesium sulfate crystals under polarized light
Image:HJS_MgSO4_092503-4.jpg| Figure 22:Magnesium sulfate crystals under polarized light with analyzer
Image:HJS_MgSO4_092503-3.jpg| Figure 23:Magnesium sulfate crystals under polarized light with analyzer and red I
Image:CeS_221209-04-2,5kx-03.JPG| Figure 24: Magnesium sulfate drop of crystallized solution under polarized light
Image:CeS_221209-04-2,5kx-02.JPG| Figure 25: Magnesium sulfate drop of crystallized solution under polarized light with analyzer
Image:CeS_221209-04-2,5kx-01.JPG| Figure 26: Magnesium sulfate drop of crystallized solution under polarized light with analyzer and red I
</gallery>
== Sodium sulfate ==
<dpl>
category = thenardite&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption=" Sodium sulfate crystallized from aqueous solution on a microscope slide " widths="200px" heights="150px" perrow="3">
Image:NaNO3 pol 02.JPG| Figure 27 : Sodium sulfate crystals under polarized light
Image:NaNO3 pol analy 02.jpg| Figure 28 : Sodium sulfate crystals under polarized light detail from previous photo
Image:NaNO3 pol+analy rot I 02.jpg| Figure 29 : Sodium sulfate crystals under polarized light with analyzer and red I
Image:HJS_Na2SO4_092503-4.jpg| Figure 30: Sodium sulfate crystals under polarized light
Image:HJS_Na2SO4_092503-3.jpg| Figure 31: Sodium sulfate under polarized light detail from previous photo
Image:| crystals under polarized light with analyzer and red I
</gallery>
== Sodium carbonate ==
<dpl>
category = Natrite&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
<gallery caption=" Sodium carbonate crystallized from aqueous solution on a microscope slide" widths="200px" heights="150px" perrow="3">
Image:HJS_Na2CO3_092903-5.jpg| Figure 32: Sodium carbonate  crystals under polarized light
Image:HJS_Na2CO3_092903-4.jpg| Figure 33: Sodium carbonate under polarized light detail from previous photo
Image:HJS_Na2CO3_092903-3.jpg| Figure 34: Sodium carbonate crystals under polarized light with analyzer and red I
</gallery>
== Sodium acetate ==
<!--
<dpl>
category = Sodium acetate&Salt
include ={Infobox_Salt}:chemical_Formula:Birefringence:Refractive_Indices:Crystal_System:optical_Orientation
table=class="wikitable sortable",Salt,chemical  formula,Birefringence,Refractive indices,Crystal system,Optical orientation
tablerow=bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%,bgcolor=lightyellow align=center|%%
</dpl>
-->
<gallery caption=" Sodium acetate crystallized from aqueous solution" widths="200px" heights="150px" perrow="3">
Image: Natriumacetat_2010.JPG| Figure 35: Sodium acetate crystals under polarized light
Image: Natriumacetat_2010 (1).JPG Figure 36: Sodium acetate crystals under polarized light, detail Figure 35
Image: Natriumacetat_2010 (2).JPG| Figure 37: Sodium acetate crystals under polarized light with analyzer and red I, detail Figure 35
</gallery>
== Weblinks ==
<references/>
[[Category:Light Microscopy]] [[Category:Schwarz,Hans-Jürgen]] [[Category:R-MSteiger]] [[Category:R-CBlaeuer]] [[Category:Bearbeitung]]
[[User:SLeithaeuser|SLeithaeuser]] 13:33, 14 April 2012 (CEST)Titelvorschlag: Microscopic identification of salts
[[User:SLeithaeuser|SLeithaeuser]] 13:33, 14 April 2012 (CEST)Titelvorschlag: Microscopic identification of salts

Latest revision as of 08:14, 29 June 2012

SLeithaeuser 13:33, 14 April 2012 (CEST)Titelvorschlag: Microscopic identification of salts

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