Calcium nitrate

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Calcium nitrate
Identifiers
CAS number10124-37-5 YesY
13477-34-4 (tetrahydrate)
PubChem24963
ChemSpider23336 YesY
UN number1454
RTECS numberEW2985000
Jmol-3D imagesImage 1
Properties
Molecular formulaCa(NO3)2
Molar mass164.088 g/mol (anhydrous)
236.15 (tetrahydrate)
Appearancecolorless solid
hygroscopic
Density2.504 g/cm3 (anhydrous)
1.896 g/cm3 (tetrahydrate)
Melting point561 °C (anhydrous)
42.7 °C (tetrahydrate)
Boiling pointdecomposes (anhydrous)
132 °C (tetrahydrate)
Solubility in wateranhydrous:
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)
Solubilitydissolves in alcohol and acetone
soluble in ammonia
almost insoluble in nitric acid
Acidity (pKa)6.0
Structure
Crystal structurecubic (anhydrous)
monoclinic (tetrahydrate)
Hazards
MSDSICSC 1037
EU IndexNot listed
NFPA 704
NFPA 704.svg
0
1
3
OX
Flash pointNon-flammable
LD50302 mg/kg (rat, oral)
Related compounds
Other anionsCalcium sulfate
Calcium chloride
Other cationsMagnesium nitrate
Strontium nitrate
Barium nitrate
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
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Calcium nitrate
Identifiers
CAS number10124-37-5 YesY
13477-34-4 (tetrahydrate)
PubChem24963
ChemSpider23336 YesY
UN number1454
RTECS numberEW2985000
Jmol-3D imagesImage 1
Properties
Molecular formulaCa(NO3)2
Molar mass164.088 g/mol (anhydrous)
236.15 (tetrahydrate)
Appearancecolorless solid
hygroscopic
Density2.504 g/cm3 (anhydrous)
1.896 g/cm3 (tetrahydrate)
Melting point561 °C (anhydrous)
42.7 °C (tetrahydrate)
Boiling pointdecomposes (anhydrous)
132 °C (tetrahydrate)
Solubility in wateranhydrous:
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)
Solubilitydissolves in alcohol and acetone
soluble in ammonia
almost insoluble in nitric acid
Acidity (pKa)6.0
Structure
Crystal structurecubic (anhydrous)
monoclinic (tetrahydrate)
Hazards
MSDSICSC 1037
EU IndexNot listed
NFPA 704
NFPA 704.svg
0
1
3
OX
Flash pointNon-flammable
LD50302 mg/kg (rat, oral)
Related compounds
Other anionsCalcium sulfate
Calcium chloride
Other cationsMagnesium nitrate
Strontium nitrate
Barium nitrate
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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 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.[1]

Production and reactivity[edit]

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

It can also be prepared from an aqueous solution of ammonium nitrate, and calcium hydroxide:

2 NH4NO3 + Ca(OH)2 → Ca(NO3)2 + 2 NH4OH

Like related alkaline earth metal nitrates (as well as LiNO3), calcium nitrate decomposes upon heating to release nitrogen dioxide:[1]

2 Ca(NO3)2 → 2 CaO + 4 NO2 + O2 ΔH = 369 kJ/mol

Applications[edit]

Use in fertilizer[edit]

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.

Waste water treatment[edit]

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.[2] 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.[3]

Concrete[edit]

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.[4] The nitrate ion leads to formation of iron hydroxide, whose protective layer reduces corrosion of the concrete reinforcement.[5]

Cooling baths[edit]

The dissolution of calcium nitrate tetrahydrate is highly endothermic (cooling). For this reason, calcium nitrate tetrahydrate is sometimes used for regenerateable cold packs.[1]

Heat storage[edit]

Calcium nitrate together with Potassium and Sodium nitrate is used to absorb and store energy in the Concentrated Solar Power plants. It can be used as a heat transfer fluid instead of the thermal oil.

References[edit]

  1. ^ a b c d 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
  2. ^ Bentzen, G.; Smith, A.T.; Bennett D.; Webster, N. J., 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 Sci. Tech. Vol 31, No 7, pp. 293-302, 1995.
  3. ^ 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. Vol 41, No 6, pp. 175-187, 2000.
  4. ^ Justines, H. (2010) "Calcium Nitrate as a Multifunctional Concrete Admixture" Concrete Magazine, Vol 44, No1, p.34. ISSN: 0010-5317
  5. ^ Al-Amoudi, O. S.; Maselehuddin, M.; Lashari, A.N.; Almussalem, A.A. "Effectiveness of corrosion inhibitors in contaminated concrete" Cement & Concrete Composites, 2003 volume 25, pp. 439-449.
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LiNO3Be(NO3)2B(NO3)3CNOFNe
NaNO3Mg(NO3)2Al(NO3)3SiPSClONO2Ar
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