| Calcium nitrate | |
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Other names
Kalksalpeter, nitrocalcite, Norwegian saltpeter, lime nitrate |
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| Identifiers | |
| CAS number | 10124-37-5 , 13477-34-4 (tetrahydrate) |
| PubChem | 24963 |
| ChemSpider | 23336 |
| UN number | 1454 |
| RTECS number | EW2985000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | Ca(NO3)2 |
| Molar mass | 164.088 g/mol (anhydrous) 236.15 (tetrahydrate) |
| Appearance | colorless solid |
| Density | 2.504 g/cm3 (anhydrous) 1.896 g/cm3 (tetrahydrate) |
| Melting point |
561 °C (anhydrous) |
| Boiling point |
decomposes (anhydrous) |
| Solubility in water | anhydrous: 121.2 g/100 mL (20 °C) 271.0 g/100 mL (40 °C) tetrahydrate: 195 g/100 mL (0 °C) 129 g/100 mL (20 °C) 363 g/100 mL (100 °C) |
| Solubility | dissolves in alcohol and acetone |
| Structure | |
| Crystal structure | cubic (anhydrous) monoclinic (tetrahydrate) |
| Hazards | |
| MSDS | ICSC 1037 |
| EU Index | Not listed |
| NFPA 704 |
0
1
3
OX
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| Flash point | Non-flammable |
| Related compounds | |
| Other anions | Calcium sulfate Calcium chloride |
| Other cations | Magnesium nitrate Strontium nitrate Barium nitrate |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Calcium nitrate, also called Norgessalpeter (Norwegian saltpeter), is the inorganic compound with the formula Ca(NO3)2. This colourless salt absorbs moisture from the air and is commonly found as a tetrahydrate. It is mainly used as a component in fertilizers but is found other applications. Nitrocalcite is the name for a mineral which is a hydrated calcium nitrate that forms as an efflorescence where manure contacts concrete or limestone in a dry environment as in stables or caverns. A variety of related salts are known including calcium ammonium nitrate decahydrate and calcium potassium nitrate decahydrate.[1]
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Norgessalpeter was the first synthetic nitrogen fertilizer compound to be manufactured. Production began at Notodden, Norway in 1905 by the Birkeland–Eyde process. Most of the world's calcium nitrate is now made in Porsgrunn.
It is produced by treating limestone with nitric acid, followed by neutralization with ammonia:
It is also a byproduct of the Odda Process for the extraction of calcium phosphate, what is the case for the production in Porsgrunn:
It can also be prepared from an aqueous solution of ammonium nitrate, and calcium hydroxide:
Like related alkaline earth metal nitrates (as well as LiNO3), calcium nitrate decomposes upon heating to release nitrogen dioxide:[1]
As of 1978, only 170,000 tons/year were produced for applications in fertilizers.[1] The fertilizer grade (15.5-0-0 + 19% Ca) is popular in the greenhouse and hydroponics trades; it contains ammonium nitrate and water, as the "double salt" 5Ca(NO3)2.NH4NO3.10H2O. Formulations lacking ammonia are also known: Ca(NO3)2.4H2O (11.9-0-0 + 16.9%Ca). A liquid formulation (9-0-0 + 11% Ca) is also offered. An anhydrous, air-stable derivative is the urea complex Ca(NO3)2.4[OC(NH2)2], which has been sold as Cal-Urea.
Calcium nitrate is used in waste water pre-conditioning for odour emission prevention and set accelerating concrete admixtures. The waste water pre-conditioning is based on establishing an anoxic biology in the waste water system. In the presence of nitrate, the metabolism for sulfates stops, thus preventing formation of hydrogen sulphide [2]. Additionally easy degradable organic matter is consumed, what otherwise can cause anaerobic conditions downstream as well as odour emissions itself. The concept is also applicable for surplus sludge treatment [3].
The use of calcium nitrate with concrete and mortar is based on two effects. The calcium ion accelerates formation of calcium hydroxide and thus precipitation and setting. This effect is used also in cold weather concreting agents as well as some combined plasticizers [4]. The nitrate ion leads to formation of iron hydroxide, whose protective layer reduces corrosion of the concrete reinforcement.[5]
The dissolution of anhydrous calcium nitrate is highly endothermic (cooling). For this reason, calcium nitrate is sometimes used for regenerateable cold packs.[1]
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