Magnesium nitrate

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Magnesium nitrate
Magnesium nitrate
Dusičnan hořečnatý.JPG
IUPAC name
Magnesium nitrate
Other names
Nitromagnesite (hexahydrate)
3D model (Jmol)
ECHA InfoCard 100.030.739
EC Number 233-826-7
RTECS number OM3750000 (anhydrous)
OM3756000 (hexahydrate)
UN number 1474
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 (264 °F; 402 K) (dihydrate)
88.9 °C (hexahydrate)
Boiling point 330 °C (626 °F; 603 K) decomposes
125 g/100 mL
Solubility moderately soluble in ethanol, ammonia
1.34 (hexahydrate)
141.9 J/mol K
164 J/mol K
-790.7 kJ/mol
-589.4 kJ/mol
Main hazards Irritant
Safety data sheet External MSDS
R-phrases R8, R36, R37, R38
S-phrases S17, S26, S36
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 otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 (hexahydrate form).[1] 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 10HNO3 + 4Mg = 4Mg(NO3)2 + NH4NO3 + 3H2O

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 nitrate reacts with alkali metal hydroxide 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, but rather its decomposition 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 inefficient, this method does not require the use of any 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.


  1. ^ Mindat,

External links[edit]

Salts and covalent derivatives of the Nitrate ion
LiNO3 Be(NO3)2 B(NO3)4 C N O FNO3 Ne
NaNO3 Mg(NO3)2 Al(NO3)3 Si P S ClONO2 Ar
KNO3 Ca(NO3)2 Sc(NO3)3 Ti(NO3)4 VO(NO3)3 Cr(NO3)3 Mn(NO3)2 Fe(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(NO3)4 Nb Mo Tc Ru Rh Pd(NO3)2 AgNO3 Cd(NO3)2 In Sn Sb(NO3)3 Te I Xe(NO3)2
CsNO3 Ba(NO3)2   Hf Ta W Re Os Ir Pt Au Hg2(NO3)2,
Pb(NO3)2 Bi(NO3)3
Po At Rn
FrNO3 Ra(NO3)2   Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
La(NO3)3 Ce(NO3)3,
Pr Nd Pm Sm Eu Gd(NO3)3 Tb Dy Ho Er Tm Yb Lu
Ac(NO3)3 Th(NO3)4 Pa U(NO3)2 Np Pu Am Cm Bk Cf Es Fm Md No Lr