Calcium nitrate

Author: Amelie Stahlbuhk
back to Nitrate

Calcium nitrate
Mineralogical name	Calcium nitrate
Chemical name	Calcium nitrate
Trivial name
Chemical formula	Ca(NO3)2
Other forms	Ca(NO3)2•2H2O (Calcium nitrate dihydrate) Ca(NO3)2•3H2O (Calcium nitrate trihydrate) Ca(NO3)2•4H2O (Nitrocalcite)
Crystal system
Crystal structure
Deliquescence humidity 20°C
Solubility (g/l) at 20°C
Density (g/cm³)	2.483 g/cm3
Molar volume	66.09 cm3/mol
Molar weight	164.09 g/mol
Transparency
Cleavage
Crystal habit
Twinning
Phase transition
Chemical behavior
Comments
Crystal Optics
Refractive Indices
Birefringence
Optical Orientation
Pleochroism
Dispersion
Used Literature
[Robie.etal:1978]Title: Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar pressure and higher temperatures Author: Robie R.A., Hemingway B.S.; Fisher J.A.

Abstract

In this page, the calcium nitrate salt is discussed. Its behavior regarding solubility and hygroscopicity will be reviewed as well as its different hydration states.

Solubility

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

Under standard conditions the tetrahydrate of calcium nitrate Nitrocalcite is the stable phase. With its relatively high solubility in water it is a highly soluble salt. The temperature dependence of the solubility is shown in the solubility diagram, where in parts the solubility increases extremely with increasing temperature. The dehydrations to the Trihydrate, Dihydrate and at least to the anhydrous calcium nitrate take place at 43 °C, 49.5 °C and 51 °C, respectively.

Hygroscopcity

Figure 2: Deliquescence behaviour of calcium nitrate in the temperature range from -30 to 80 °C. The water acitivity a_w is plotted against the temperature.

Calcium nitrate and its phases are hygroscopic salts. At a temperature of 25 °C the Nitrocalcite has a deliquescence humidity of about 50 %. The phase transitions to the other two hydrated forms and to the anhydrous calcium nitrate occur at relative humidities of 22 %, 13 % and 9 %, respectively.

Literature

[Robie.etal:1978]

Robie R.A., Hemingway B.S.; Fisher J.A. (1978): Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar pressure and higher temperatures. In: U.S. Geol. Surv. Bull, 1452 ()

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.

the relative humidity, above which a material, e.g. a salt, absorbes humidity from the air and dissolves.