Kalksalpeter, nitrocalcite, Norwegian saltpeter, lime nitrate
|Molar mass||164.088 g/mol (anhydrous)
236.15 g/mol (tetrahydrate)
|Density||2.504 g/cm3 (anhydrous)
1.896 g/cm3 (tetrahydrate)
|Melting point||561 °C (1,042 °F; 834 K) (anhydrous)
42.7 °C (109 °F; 316 K) (tetrahydrate)
|Boiling point||decomposes (anhydrous)
132 °C (270 °F; 405 K) (tetrahydrate)
1212 g/L (20 °C)
2710 g/L (40 °C)
1950 g/L (0 °C)
1290 g/L (20 °C)
3630 g/L (100 °C)
|Solubility||dissolves in alcohol and acetone
soluble in ammonia
almost insoluble in nitric acid
|Crystal structure||cubic (anhydrous)
|EU Index||Not listed|
LD50 (Median lethal dose)
|302 mg/kg (rat, oral)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
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 has 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.
Production and reactivity
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:
- CaCO3 + 2 HNO3 → Ca(NO3)2 + CO2 + H2O
It is also an intermediate product of the Odda Process:
- Ca3(PO4)2 + 6 HNO3 + 12 H2O → 2 H3PO4 + 3 Ca(NO3)2 + 12 H2O
- 2 NH4NO3 + Ca(OH)2 → Ca(NO3)2 + 2 NH4OH
- 2 Ca(NO3)2 → 2 CaO + 4 NO2 + O2 ΔH = 369 kJ/mol
Use in fertilizer
As of 1978, only 170,000 tons/year were produced for applications in fertilizers. 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. This is called calcium ammonium nitrate. 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.
Waste water treatment
Calcium nitrate is used in waste water pre-conditioning for odour emission prevention. 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. Additionally easy degradable organic matter is consumed, which otherwise can cause anaerobic conditions downstream as well as odour emissions itself. The concept is also applicable for surplus sludge treatment.
Calcium nitrate is used in set accelerating concrete admixtures. This use 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. The nitrate ion leads to formation of iron hydroxide, whose protective layer reduces corrosion of the concrete reinforcement.
The dissolution of calcium nitrate tetrahydrate is highly endothermic (cooling). For this reason, calcium nitrate tetrahydrate is sometimes used for regenerable cold packs.
- Wolfgang Laue, Michael Thiemann, Erich Scheibler, Karl Wilhelm Wiegand “Nitrates and Nitrites” in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim.doi:10.1002/14356007.a17_265. Article Online Posting Date: June 15, 2000
- Bentzen, G; Smith, A; Bennett, D; Webster, N; Reinholt, F; Sletholt, E; Hobson, J (1995). "Controlled dosing of nitrate for prevention of H2S in a sewer network and the effects on the subsequent treatment process". Water Science and Technology 31 (7): 293. doi:10.1016/0273-1223(95)00346-O.
- Einarsen, A.M.; ÆeesØy, A.; Rasmussen, A. I.; Bungum, S.; Sveberg, M. (2000). "Biological prevention and removal of hydrogen sulphide in sludge at Lillehammer Wastewater Treatment Plant". Wat. Sci. Tech. 41 (6): 175–187.
- Justines, H. (2010) "Calcium Nitrate as a Multifunctional Concrete Admixture" Concrete Magazine, Vol 44, No1, p.34. ISSN: 0010-5317
- Al-Amoudi, Omar S.Baghabra; Maslehuddin, Mohammed; Lashari, A.N; Almusallam, Abdullah A (2003). "Effectiveness of corrosion inhibitors in contaminated concrete". Cement and Concrete Composites 25 (4–5): 439. doi:10.1016/S0958-9465(02)00084-7.
|Salts and the ester of the Nitrate ion|