Aluminum Bromide Formula – Structure, Properties, Uses, Sample Questions

Aluminum, one of the components of aluminium bromide, accounts for over 8.1 percent of the Earth’s crust, making it one of the most prevalent minerals on the planet. Despite the fact that it is present in a wide range of compounds on Earth, aluminium is rarely discovered in its free metal state. Instead, it is frequently found in minerals such as bauxite and cryolite. Bromine, the other component of aluminium bromide, is a poisonous, oily, crimson liquid. Bromine, in addition to being employed in the manufacture of dyes, pesticides, and fertilizers, is occasionally detected in trace amounts in living species, although having no known biological purpose in humans.

What is Aluminium Bromide?

Aluminum bromide is a pale yellow chemical solution, also known as tribromoalumane or aluminium tribromide (the most common form). It is a colorless, hygroscopic solid that may be sublimated. Its molecular or chemical formula is AlBr₃. 

It appears in its anhydrous state as a white to yellowish-red compound with a lumpy solid and a strong odour. It appears as a liquid in its watery form. It is extremely damaging to the eyes, mucous membranes, and skin. It is frequently utilized in the production of many compounds. It is a solution in a wide range of organic solvents, including benzene, toluene, simple hydrocarbons, nitrobenzene, and xylene.

Structure of Aluminium Bromide

The formula of Aluminium Bromide is made up of one aluminium cation (Al³⁺) and one bromide anion (Br^–). Therefore, the molecular or chemical formula of Barium sulfate is AlBr₃. Its chemical formula reveals that it is composed of one aluminium atom and three bromine atoms. It has a molecular mass of 266.694 g/mol as an anhydrous chemical and 374.785 g/mol as a hexahydrate. It has a monoclinic crystalline structure with a positive dipole moment.

Physical Properties of Aluminium Bromide

• Aluminium Bromide is a white to pale yellow powder with a pungent smell.
• It is a colorless, sublimable hygroscopic solid which occurs mostly in the form of Aluminium tribromide.
• The density of Aluminium Bromide is 3.2 g/cm³ as anhydrous and 2.54 g/cm³ as a hexahydrate.
• The melting point of Aluminium Bromide is 97.5 °C as an anhydrous and 93 °C as a hexahydrate.
• The boiling point of Aluminium Bromide is 255 °C as an anhydrous and 252 °C as a hexahydrate.
• The heat capacity of Aluminium Bromide is 100.6 J J/mol K.
• The standard molar entropy of Aluminium Bromide is 180.2 J J/mol K.
• The standard enthalpy of formation of Aluminium Bromide is −572.5 kJ/mol.
• Its aqueous solution is neutral in nature with a pH of 6 at 14 °C.
• It is slightly soluble in methanol, diethyl ether, acetone but entirely soluble in water.

Chemical Properties of Aluminium Bromide

• At 100 °C, aluminium tribromide combines with carbon tetrachloride to produce carbon tetrabromide.

4 AlBr₃ + 3 CCl₄ → 4 AlCl₃ + 3 CBr₄

• It reacts with phosgene gas to produce carbonyl bromide and aluminium chlorobromide.

AlBr₃ + COCl₂ → COBr₂ + AlCl₂Br

• Water hydrolyzes Al₂Br₆ in line with the properties of Lewis acid. Furthermore, water hydrolysis occurs during the development of HBr and the production of the Al-OH-Br species. It also reacts fast with alcohol and carboxylic acids.

Uses of Aluminium Bromide

• It is used as a catalyst in Friedel–Crafts reactions.
• It is used as a medication in the field of health.
• As it is a more powerful Lewis acid than Al₂Cl₆, it is employed in industries to create various substances.
• It acts as an electron pair acceptor to increase the reactivity of a substrate.
• It has a number of specific chemical uses in synthesis and extractive metallurgy.

Sample Questions

Question 1: What is the process for the preparation of Aluminium Bromide?

Solution:

Aluminium bromide is prepared by the reaction of Hydrogen bromide (HBr) with aluminium metal (Al).

2 Al + 6 HBr → Al₂Br₆ + 3 H₂

The second method to obtain Aluminium Bromide is through bromination.

2 Al + 3 Br₂ → Al₂Br₆

Question 2: How does aluminium bromide exist in nature?

Solution:

In the solid state, solutions in noncoordinating solvents (e.g., CS₂), the melt, and the gas phase, the dimeric form of aluminium tribromide (Al₂Br₆) predominates. These dimers only break down into monomers at high temperatures.

Al₂Br₆ → 2 AlBr₃ (ΔH°diss = 59 kJ/mol)

Question 3: What are the side effects of aluminium bromide?

Solution:

Aluminum Bromide can harm you if inhaled. It is a highly corrosive chemical and direct contact can severely irritate and burn the skin and eyes, perhaps causing eye damage. It may irritate the nose, throat, and lungs, resulting in coughing, wheezing, and/or shortness of breath. Aluminum bromide is a reactive chemical that might cause an explosion.

Question 4: How can one check if he/she is exposed to aluminium bromide?

Solution:

The exposure of hazardous materials such as aluminium bromide should be assessed on a regular basis. This might entail taking personal and regional air samples. A worker’s employer can provide him with copies of the sample findings.

Question 5: Explain some methods of reducing exposure to aluminium bromide.

Solution:

Methods of Reducing Exposure to Aluminium Bromide are:

1. Enclose activities and employ local exhaust ventilation at the place of chemical discharge wherever practicable. Respirators should be worn if no local exhaust ventilation or enclosure is employed.
2. Wear appropriate job clothes.
3. Wash carefully after being exposed to aluminum bromide and at the end of the workshift.
4. Furthermore, as part of a continuing education and training effort, communicate to potentially exposed personnel all information on the health and safety concerns of Aluminum Bromide.