- Magnesium nitrate
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Magnesium nitrate 
Magnesium nitrateOther namesNitromagnesite (hexahydrate)Identifiers CAS number 10377-60-3 
,
15750-45-5 (dihydrate)
13446-18-9 (hexahydrate)PubChem 25212 UN number 1474 RTECS number OM3750000 (anhydrous)
OM3756000 (hexahydrate)Properties Molecular formula Mg(NO3)2 Molar mass 148.30 g/mol
256.41 g/mol (hexahydrate)Appearance White crystalline solid Density 2.3 g/cm3 (anhydrous)
1.46 g/cm3, solid (dihydrate)Melting point 88.9 °C (362 K), hexahydrate
Boiling point 330 °C (603 K) decomp.
Solubility in water 125 g/100 mL Solubility moderately soluble in ethanol Refractive index (nD) 1.34 (hexahydrate) Hazards MSDS External MSDS EU Index Not listed R-phrases R8, R36, R37, R38 S-phrases S17, S26, S36 Main hazards Irritant NFPA 704 
023OXFlash point Non-flammable Related compounds Other anions Magnesium sulfate
Magnesium chlorideOther cations Beryllium nitrate
Calcium nitrate
Strontium nitrate
Barium nitrate
nitrate (verify) (what is: 
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)Infobox references Magnesium nitrate is a hygroscopic salt with the formula Mg(NO3)2. In air, it quickly forms the hexahydrate with the formula Mg(NO3)2·6H2O (and molar weight of 256.41 g/mol). It is very soluble in both water and ethanol.
Contents
Uses
Magnesium nitrate occurs in mines and caverns as nitromagnesite. This form is not common, although it may be present where guano contacts magnesium-rich rock. It is used in the ceramics, printing, chemical and agriculture industries. Its fertilizer grade has 10.5% nitrogen and 9.4% magnesium, so it is listed as 10.5-0-0 + 9.4% Mg. Fertilizer blends containing magnesium nitrate usually have ammonium nitrate, calcium nitrate, potassium nitrate and micronutrients; these blends are used in the greenhouse and hydroponics trade.
Production
The magnesium nitrate used in commerce is a man-made product. It can be synthesized in a variety of ways. The reaction between nitric acid and magnesium metal
- 2 HNO3 + Mg → Mg(NO3)2 + H2
- 2 HNO3 + MgO → Mg(NO3)2 + H2O
results in magnesium nitrate.
Magnesium hydroxide and ammonium nitrate also react to form magnesium nitrate as ammonia is released as a by-product.
- Mg(OH)2 + 2 NH4NO3 → Mg(NO3)2 + 2 NH3 + 2 H2O
Reactions
Magnesium Nitrates with metal alkaline to form the corresponding nitrate
- Mg(NO3)2 + NaOH → 2 Mg(OH)2 + NaNO3
Since magnesium nitrate has a high affinity for water, heating the hexahydrate does not result in the dehydration of the salt. Instead, magnesium nitrate hexahydrate decomposes into magnesium oxide, oxygen, and nitrogen oxides.
- 2 Mg(NO3)2 → 2 MgO + 4 NO2 + O2
The absorption of these nitrogen oxides in water is one possible route way to synthesize nitric acid. Although it is inefficient, it does not require the use of another strong acid.
Anhydrous magnesium nitrate is also used to increase the concentration of nitric acid past its azeotrope of approximately 68% nitric acid and 32% water. It is also occasionally used as a desiccant.
References
External links
- International Chemical Safety Card 1041
- Liquid Chemistry
- Nitromagnesite Mineral Data
- Magnesium Nitrate MSDS
Magnesium compounds Categories:- Magnesium compounds
- Nitrates
- Oxidizing agents
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