Magnesium nitrate

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Magnesium nitrate
Magnesium nitrate
Dusičnan hořečnatý.JPG
CAS number 10377-60-3 YesY
15750-45-5 (dihydrate)
13446-18-9 (hexahydrate)
PubChem 25212
ChemSpider 23415
EC number 233-826-7
UN number 1474
RTECS number OM3750000 (anhydrous)
OM3756000 (hexahydrate)
Jmol-3D images Image 1
Molecular formula Mg(NO3)2
Molar mass 148.32 g/mol (anhydrous)
184.35 g/mol (dihydrate)
256.41 g/mol (hexahydr.)
Appearance White crystalline solid
Density 2.3 g/cm3 (anhydrous)
2.0256 g/cm3 (dihydrate)
1.464 g/cm3 (hexahydrate)
Melting point 129 °C (dihydrate)
88.9 °C (hexahydrate)
Boiling point 330 °C (603 K) decomp.
Solubility in water 125 g/100 mL
Solubility moderately soluble in ethanol, ammonia
Refractive index (nD) 1.34 (hexahydrate)
Crystal structure cubic
heat capacity
141.9 J/mol K
Std molar
164 J/mol K
Std enthalpy of
-790.7 kJ/mol
Gibbs free energy ΔG -589.4 kJ/mol
MSDS External MSDS
EU Index Not listed
R-phrases R8, R36, R37, R38
S-phrases S17, S26, S36
Main hazards Irritant
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other anions Magnesium sulfate
Magnesium chloride
Other cations Beryllium nitrate
Calcium nitrate
Strontium nitrate
Barium nitrate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
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.


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.


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

or magnesium oxide

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


Magnesium Nitrates with metal alkaline to form the corresponding nitrate

Mg(NO3)2 + 2 NaOH → Mg(OH)2 + 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 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.


External links[edit]

LiNO3 Be(NO3)2 B(NO3)3 C N O F Ne
NaNO3 Mg(NO3)2 Al(NO3)3 Si P S ClONO2 Ar
KNO3 Ca(NO3)2 Sc(NO3)3 Ti V Cr(NO3)3 Mn(NO3)2 Fe(NO3)3 Co(NO3)2, Co(NO3)3 Ni(NO3)2 Cu(NO3)2 Zn(NO3)2 Ga(NO3)3 Ge As Se Br Kr
RbNO3 Sr(NO3)2 Y Zr Nb Mo Tc Ru Rh Pd(NO3)2 AgNO3 Cd(NO3)2 In Sn Sb Te I Xe
CsNO3 Ba(NO3)2 Hf Ta W Re Os Ir Pt Au Hg2(NO3)2, Hg(NO3)2 Tl(NO3)3 Pb(NO3)2 Bi(NO3)3 Po At Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
La Ce Pr Nd Pm Sm Eu Gd(NO3)3 Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UO2(NO3)2 Np Pu Am Cm Bk Cf Es Fm Md No Lr