[Chemistry Class Notes] on Magnesium Nitrate Formula Pdf for Exam

Magnesium nitrate is a chemical compound which is visible in white colour. As already known a nitrate is any polyatomic ion made up of oxygen and nitrogen having a chemical formula NO3–, which clearly shows that it is an anion with one negative charge. It is well known that magnesium atoms are capable of donating two electrons to form a cation, in order to achieve stable electronic configuration. Hence, a cation of magnesium and a polyatomic anion of nitrate combine with each other to form a neutral salt compound having the magnesium nitrate formula. Thus, the chemical formula of magnesium nitrate is given as Mg(NO3). It can be either present in anhydrous or hydrated form. The magnesium nitrate chemical formula can thus also be written as Mg(NO3)(H2O)x where x = 6, 2, 0. 

General Physical Properties of Magnesium Nitrate

The salt of magnesium nitrate is also known as nitromagnesite, whose largest deposits are found in mines and caverns. The salt of magnesium nitrate has the physical form of a white crystalline solid mineral. It is an alkaline earth metal nitrate as magnesium belongs to the alkaline Group II in the modern periodic table.

The structural formula magnesium nitrate has is given below showing the arrangement of the ions involved as per the chemical formula of magnesium nitrate :

Some of the Most Common Physical Properties of Magnesium Nitrate are Described Below:

• The molar mass of magnesium nitrate as calculated from the magnesium nitrate chemical formula is 148.32 g/mol in anhydrous form, 184.35 g/mol in dihydrate form and 256.42 gm/mol in hexahydrate form.

• The magnesium nitrate formula clearly shows that it is a very strong electrolyte. 

• The compound identified by the magnesium nitrate ionic formula is odourless compound. 

• The density of magnesium nitrate is 2.3 g/cm3 in anhydrous form, 2.00256 g/cm3 in dihydrate form and 1.464 g/cm3 in the hexahydrate form. 

• The melting point of magnesium nitrate is 129℃ in dihydrate form and 88.9℃ in hexahydrate form and at 330℃ it starts to decompose.

• It is very much soluble in water, ethanol, and ammonia because of the ionic properties as shown by the magnesium nitrate chemical formula.

• The crystal structure of magnesium nitrate is a cubic crystalline structure. 

• The salt of magnesium nitrate has the capacity to hold and retain water as is well known from the chemical formula magnesium nitrate has in both the hydrate forms. 

• It is a non flammable compound and mostly known as an irritant as its harmful effects. 

Reactions and Uses

The industrial synthesis of magnesium nitrate takes place by the neutralization of nitric acid with magnesium hydroxide or any of the magnesium salts. The reactions for this production method is given below with the chemical formula for magnesium nitrate/molecular formula of magnesium nitrate and other compounds:

2HNO3 + Mg(OH)2 → Mg(NO3)2 + H2O 

Other methods for the neutralization of nitric acid apart from using magnesium hydroxide also include the mixing of stoichiometric amounts of ammonium nitrate and magnesium hydroxide, magnesium bicarbonate or magnesium carbonate, etc.

Since magnesium carbonate has affinity for water, heating of the hexahydrate form of magnesium nitrate does not result in the formation of anhydrous salt but leads to complete decomposition of the ionic compound into magnesium oxide, oxygen and nitrogen oxides. The reaction for this decomposition is as follows:

2Mg(NO3)2 → 2MgO + 4NO2 + O2 

The nitric acid produced is then absorbed in water for the production of nitric acid. The speciality of this method is that such a production of nitric acid does not involve the use of a strong acid but economically this is also an inefficient method. 

The main and principal use of magnesium nitrate is in the preparation of the concentrated form of nitric acid. It is also used in the making of fertilizers. The fertilizer grade magnesium nitrate includes 10.5% nitrogen and 9.4% magnesium. The fertilizer blends are known to contain magnesium nitrate along with ammonium nitrate, calcium nitrate, potassium nitrate, and the micronutrients in most of the cases. These blends are typically used in the greenhouse and hydroponics trade.