Nitrocalcite

Nitrocalcite
Mineralogical name	Nitrocalcite
Chemical name	Calcium Nitrate Tetrahydrate
Trivial name	Nitrate of lime
Chemical formula	Ca(NO3)2•4H2O
Other forms	Ca(NO3)2•2H2O (calcium nitrate dihydrate) Ca(NO3)2•3H2O (calcium nitrate trihydrate)
Crystal system	monoclinic
Crystal structure
Deliquescence humidity 20°C	53.06%
Solubility (g/l) at 20°C	7.726 mol/kg
Density (g/cm³)	1.82 g/cm3
Molar volume	129.8 cm3/mol
Molar weight	236.15 g/mol
Transparency	transparent
Cleavage
Crystal habit
Twinning
Phase transition
Chemical behavior
Comments
Crystal Optics
Refractive Indices	nx = 1.465 ny = 1.498 nz = 1.504
Birefringence	Δ = 0.039
Optical Orientation	negative
Pleochroism
Dispersion
Used Literature
[Steiger.etal:2014]Title: Weathering and Deterioration Author: Steiger, Michael; Charola A. Elena; Sterflinger, Katja [Broul.etal:1981]Title: Solubility in organic two component systems Author: Broul M., Nyvlt J.; Soehnel O.

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Solubility

Figure 1 Solubility of calcium nitrate in water. The molality m [n(Ca(NO₃)₂•xH₂O)•kg(H₂O)^-1] is plotted versus the temperature.

At 20 °C nitrocalcite is the stable phase of calcium nitrate. The salt has got a high solubilty in water and due to the temperature range of its stability it is relevant as a crystallizing phases under ambient conditions.

Hygroscopicity

Figure 2 Deliquescence behaviour of calcium nitrate. The water activity a_w is plotted versus the temperature.

Table 1: Deliquescence humidities of nitrocalcite at different round temperatures [Steiger.etal:2014]Title: Weathering and Deterioration
Author: Steiger, Michael; Charola A. Elena; Sterflinger, Katja

0°C	10°C	20°C	30°C	40°C	50°C
63.8%r.h.	58.8%r.h.	53.1%r.h.	46.0%r.h.	35.5%r.h.	21.3%r.h. (Ca(NO3)2•3H2O)

Under the polarizing microscope

• Crystallized from a saturated solution with ethanol addition
• 

  in simple polarized light

• 

  under crossed polarizers

• 

  under crossed polarizers and Red I

• Crystallized in a micro climate chamber
• 

  in simple polarized light

• 

  under crossed polarizers and Red I

Literature

[Broul.etal:1981]	Elsevier (eds.) Broul M., Nyvlt J.; Soehnel O. (1981): Solubility in organic two component systems, Elsevier
[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.

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.