Aluminium nitrate is a solid white coloured inorganic chemical compound. 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 aluminium atoms are capable of donating three electrons to form a cation, in order to achieve stable electronic configuration. Hence, a cation of aluminium and a polyatomic anion of nitrate combine with each other to form a neutral salt compound having the aluminium nitrate formula. Thus, the chemical formula of Aluminium nitrate is given as Al(NO3)3 which is also the aluminium nitrate symbol. It can be either present in an anhydrous or hydrated form. The aluminium nitrate chemical formula can thus also be written as Mg(NO3)3.9(H2O).
General Properties of Aluminium Nitrate
The salt of aluminium nitrate is a salt of aluminium and nitric acid. The salt of Aluminium nitrate has the physical form of a white crystalline solid. It is a transition metal nitrate as aluminium belongs to Group III, the first group of transition metal elements in the modern periodic table. Other common names of this salt include nitric aluminium salt, aluminium nitrate, aluminium (III) nitrate.
The structural formula aluminium nitrate is given below showing the arrangement of the ions involved as per the chemical formula of aluminium nitrate :
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Some of the Most Common Physical Properties of Aluminium Nitrate are Described below:
The molecular mass of aluminium nitrate as calculated from the aluminium nitrate chemical formula is 212.996 g/mol in anhydrous form, 375.134 g/mol in nonahydrate form.
The aluminium nitrate formula clearly shows that it is a very strong electrolyte and thus is a very strong oxidizing agent.
The compound identified by the aluminium nitrate ionic formula is odourless.
The density of aluminium nitrate is 1.72 g/cm3 in the nonahydrate form.
The melting point of aluminium nitrate is 66℃ in anhydrous form and 73.9℃ in nonahydrate form and at 150℃ the nonahydrate form starts to decompose.
It is very much soluble in water, ethanol, methanol, and ethylene glycol because of the ionic and structural properties as shown by the aluminium nitrate chemical formula and its structural formula.
The salt of aluminium nitrate has the capacity to hold and retain water as is well known from the chemical formula aluminium nitrate has in both the hydrate forms.
The flash point of aluminium nitrate occurs at 35℃.
Reactions and Uses
The synthesis of aluminium nitrate takes place by the neutralization of dilute nitric acid with aluminium (III) chloride or any of the aluminium salts such as aluminium hydroxide. This is because when any aluminium salt is reacted with a concentrated form of nitric acid it forms a passivation layer. In this reaction, nitrosyl chloride is produced as a by-product which is automatically removed as it bubbles out of the solution. The reactions for this production method is given below with the chemical formula for aluminium nitrate/molecular formula of aluminium nitrate and other compounds:
3HNO3 (dilute) + AlCl3 → Al(NO3)3 + 3HCl
Another method to produce aluminium nitrate involves a metathesis reaction. In this metathesis reaction, aluminium sulfate reacts with a nitrate salt of any suitable cation like barium, strontium, calcium, silver, or lead. An example of such a reaction is given below, in which aluminium sulfate reacts with barium nitrate in order to yield aluminium nitrate. The reaction with the chemical formula for aluminium nitrate/molecular formula of aluminium nitrate is given below:
Al2(SO4)3 + 3Ba(NO3)2 → 2Al(NO3)3 + 3BaSO4
Aluminium nitrate salt is much less encountered when compared to other salts like aluminium chloride and aluminium sulfate. Although, having its own significant use, industrially aluminium chloride and sulfate are produced and found more as compared to aluminium nitrate.
The main and principal use of aluminium nitrate is in the preparation of alumina which is further used in many different applications such as preparation of insulating papers, in making of cathode ray tube heating elements, on transformer core laminates. The hydrated forms of aluminium nitrate are used for the extraction process of actinide series of elements as given in the modern periodic table. Because aluminium nitrate is a very strong oxidizing agent it is used for the processes such as tanning of leather, antiperspirants, corrosion inhibitors, in the process of extraction of uranium, in the refining of petroleum products, and of course as a nitrating agent.
It is used in the laboratory and classrooms for exhibiting the reaction:
Al(NO3)3 + 3NaOH → Al(OH)3 + 3NaNO3