Aluminium Nitrate Formula – Chemical Structure, Properties, Uses

Aluminium Nitrate Formula: Aluminium Nitrate is a white crystalline salt of Aluminium and Nitric acid, where Aluminium \(\left( {{\text{Al}}} \right)\) is a metal and Nitrate ion \(\left( {{\text{NO}}_3^ – } \right)\) is a polyatomic ion. We know that aluminium atoms can donate three electrons to form a stable cation, i.e., to achieve a stable electronic configuration. Hence, an aluminium cation and a polyatomic nitrate anion combine with each other to form a salt known as Aluminium Nitrate.

The chemical formula of Aluminium Nitrate is \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.\) This compound belongs to a group of reactive nitrite salt where nitrate ion is a conjugate base of nitric acid. Aluminium Nitrate is water-soluble, and it exists as a crystalline hydrate salt known as Aluminium nitrate nonahydrate, \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.9{{\text{H}}_2}{\text{O}}.\) Aluminium Nitrate is widely used in the tanning of leather, making antiperspirants (deodorants, body spray, etc.), in uranium extraction for nuclear reactors, it is also used during the refining of gasoline, and many more. In this article, we will learn about the chemical formula, properties as well as uses of Aluminium Nitrate in detail.

Chemical Formula and Structure of Aluminium Nitrate

The chemical formula of Aluminium Nitrate is \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.\) As it is an ionic compound, Aluminium Nitrate dissociates in water to form \({\text{A}}{{\text{l}}^{3 + }}\) cation and \({\text{NO}}_3^ – \) anion. It is soluble in water at conditions \(160\,{\text{g}}/100\,{\text{mL}}\) at \({100^{\text{o}}}{\text{C}}.\) When Aluminum Nitrate is dissolved in water, the aqueous solution is acidic because Nitric acid is a strong acid while Aluminum is a weak base.

As inferred from the chemical formula itself, \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}\) is formed from one \({\text{A}}{{\text{l}}^{3 + }}\) cation and three \({\text{NO}}_3^ – \) anion. Apart from Aluminium Nitrate, it is also known as Nitric Aluminium salt and Aluminium (III) nitrate. When dissolved in water, it shows weak acidic properties. The aluminium ion tends to remove the hydroxide ions from some of the water molecules as it has a strong positive charge enough to attract hydroxide ions. This leaves some \({{\text{H}}^ + }\) ions which lower the pH of the solution, making it acidic.

Derivation of Chemical Formula of Aluminium Nitrate

The chemical formula of Aluminium Nitrate is \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.\) We know that Aluminium is a metal, and it contains \(3\) electrons in its outer electron shell. It is more favourable for Aluminium to lose three electrons than to gain five. So, on losing its three negatively charged particles, it gets a net electric charge of \(+3\) and \({\text{A}}{{\text{l}}^{3 + }}\) cation is formed.

On the other hand, Nitrate is a polyatomic ion as it is the combination of one nitrogen atom and three oxygen atoms. It carries a unit negative charge, denoted by the formula \({\text{NO}}_3^ – .\) In order to maintain the electrical neutrality of the compound, three nitrate ions are needed to cancel out the \(+3\) charge of the Aluminium ion. Thus, it forms the combination as:
\({\text{A}}{{\text{l}}^{3 + }} + 3{\text{NO}}_3^ – \to {\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}\)

Physical Properties of Aluminium Nitrate

Synthesis of Aluminium Nitrate

1. Aluminium nitrate is synthesised by the neutralisation reaction of dilute Nitric acid with Aluminium (III) chloride or any other aluminium salt. Concentrated nitric acid cannot be used for this reaction because when any aluminium salt reacts with concentrated nitric acid, it forms a passivation layer. In this reaction, nitrosyl chloride is produced as a by-product which oozes out as bubbles from the solution. The chemical reaction involved in this process is given below:
\(3{\text{HN}}{{\text{O}}_3}\left( {{\text{dilute}}} \right) + 3{\text{AlC}}{{\text{l}}_3} \to {\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3} + 3{\text{HCl}}\)
2. Another method for the preparation of Aluminium Nitrate is accompanied by metathesis or double displacement reaction. In this metathesis reaction, Aluminium sulphate reacts with a nitrate salt of a cation like barium nitrate, strontium nitrate, calcium nitrate, silver nitrate, or lead nitrate. The chemical reaction for aluminium sulphate and barium nitrate is given below:
\({\text{A}}{{\text{l}}_2}{\left( {{\text{S}}{{\text{O}}_4}} \right)_3} + 3{\text{Ba}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_2} \to 2{\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3} + {\text{BaS}}{{\text{O}}_4}\)

Uses of Aluminium Nitrate

1. The principal use of Aluminium Nitrate is in the preparation of alumina or aluminium oxide, which is used in making corrosion-resistant parts, electronic items, etc.
2. Aluminium nitrate is used in our daily life as antiperspirants, i.e., as perfumes, deodorants, etc.
3. Tanning of leather products requires Aluminum nitrate.
4. Aluminium nitrate is also used during the refining of gasoline. So, we can say that this compound is indirectly used to drive our vehicles!
5. Aluminium nitrate is useful in providing us electricity as it is used in the uranium extraction process, which is a necessary fuel of a nuclear reactor. These nuclear reactors generate electricity. Aluminium nitrate helps in the corrosion inhibiting process; as a result, it prevents corrosion of some parts of nuclear reactors that may get corroded with time.
6. It is used to make insulating papers used as a heating element component of cathode ray tubes.
7. The hydrated forms of aluminium nitrate are used for the extraction of the elements of the actinide series of the modern periodic table because aluminium nitrate is a very strong oxidising agent.
8. It is also used as a nitrating agent in a chemical reaction.

Summary

Aluminium Nitrate is an inorganic salt formed from Aluminium and Nitric acid, where Aluminium \(\left( {{\text{Al}}} \right)\) is a metal and Nitrate ion \(\left( {{\text{NO}}_3^ – } \right)\) is a polyatomic ion. The chemical formula of Aluminium Nitrate is \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}\) as aluminium atoms can donate three electrons to achieve a stable electronic configuration.

Hence, \({\text{A}}{{\text{l}}^{3 + }}\) cation and a polyatomic nitrate anion \({{\text{NO}}_3^ – }\) combine with each other to form Aluminium Nitrate. It is a white crystalline salt, and it belongs to a group of reactive nitrate salt. Aluminium Nitrate is hygroscopic, and it exists as a crystalline hydrate salt known as Aluminium nitrate nonahydrate, having chemical formula as \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.9{{\text{H}}_2}{\text{O}}.\) Tough not directly, but indirectly, Aluminium Nitrate has a wide range of applications such as in tanning of leather, making antiperspirants (deodorants, body spray, etc.), in uranium extraction for nuclear reactors that produce electricity, in the refining of gasoline, etc.

FAQs on Aluminium Nitrate Formula

Q.1. What is the \({\text{pH}}\) of \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}\)?
Ans: An aqueous solution of \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}\) is acidic because Nitric acid is a strong acid while Aluminum is a weak base. Hence, its \({\text{pH}}\) is nearby \(3.0.\)

Q.2. What is the formula of Aluminum Nitrate?
Ans: The chemical formula of Aluminum Nitrate is \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.\) It is formed from one \({\text{A}}{{\text{l}}^{3 + }}\) cation and three \({{\text{NO}}_3^ – }\) anion.

Q.3. What is Aluminum Nitrate composed of?
Ans: The chemical formula of Aluminium Nitrate is \({\text{Al}}{\left( {{\text{N}}{{\text{O}}_3}} \right)_3}.\) It is an ionic compound that is made up of \({\text{A}}{{\text{l}}^{3 + }}\) cation and \({{\text{NO}}_3^ – }\) anion. Aluminium Nitrate is composed of Nitric acid and Aluminum.

Q.4. What do you use Aluminum Nitrate for?
Ans: Aluminium Nitrate is used in the tanning of leather, making antiperspirants (deodorants, body spray, etc.), in uranium extraction for nuclear reactors, during the refining of gasoline, etc.

Q.5. Is Aluminum Nitrate dangerous?
Ans: Aluminum Nitrate is dangerous to aquatic animals because it releases hydrogen ions in water, making it acidic, which proves to be harmful to aquatic habitat.

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