Aluminium Fluoride Formula

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Aluminium fluoride is a colourless chemical compound with a molecular formula AlF3. It is mainly used in the production of aluminium. It occurs naturally as oskarssonite and rosenbergite. It can be manufactured synthetically too. The majority of aluminium fluoride is produced by treating hydrogen fluoride with alumina or aluminium oxide at 700 °C. In this short piece of article, learn more about aluminium fluoride formula, its chemical structure, properties and uses.

Aluminium Fluoride Properties

Properties of Aluminium Flouride
NameAluminium Fluoride
AppearanceHygroscopic white or colourless solid
Chemical FormulaAlF3
Melting Point1,291 °C (anhydrous)
Molar Mass83.977 g/mol (anhydrous)101.992 g/mol (monohydrate)138.023 g/mol (trihydrate)
Density3.10 g/cm3 (anhydrous)2.17 g/cm3 (monohydrate)3.10 g/cm3 (trihydrate)
Solubility in WaterSoluble in water

Aluminium Fluoride Structure

Aluminium Fluoride Uses

  • Used as an additive for the production of aluminium by electrolysis
  • Used in the fermentation process in beer and wine factories
  • Used in the production of low index optical thin film
  • Used as a catalyst in the organic compound synthesis process

Physical Properties of Aluminium Fluoride 

  • Aluminum fluoride has the appearance of white powder or granules. Furthermore, aluminum fluoride has an odorless property. Furthermore, this combination is denser than water.
  • At a temperature of 25°C, its solubility in water is approximately.559g/100 mL.
  • Furthermore, this molecule is very marginally soluble in alkalis and acids.
  • Even highly concentrated acid has less effect on Aluminium fluoride
  • Aluminum fluoride has a very high melting point of 1291 degrees Celsius.
  • At 1238 °C, its vapor pressure is 1 mm.
  • As compared to trialkylaluminiums, the chemical is less vulnerable to oxidation.
  • In nature, aluminum fluoride is non-flammable.
  • When this chemical reaches the point of breakdown, it generates very hazardous hydrogen fluoride vapors.
  • Aluminum fluoride sublimates at a high temperature of 1272 °C and a pressure of 760 mmHg. 

Chemical Properties of Aluminium Fluoride 

Experts are aware of many hydrates of aluminum fluoride in addition to AlF3. Furthermore, with the formula AlF3.  xH2O, these compounds comprise monohydrate x = 1, two polymorphs of a trihydrate x = 3, hexahydrate x = 6, and x = 9 nonahydrate. Most aluminum fluoride is generated by processing alumina with hydrogen fluoride. Furthermore, this occurs at a temperature of 700 °C. Fluorosilicic acid may be used to make aluminum fluoride.  Alternatively, ammonium hexafluoroaluminate can be thermally decomposed to produce aluminum fluoride. 

Uses of Aluminium Fluoride 

  • Aluminum fluoride is primarily used as an additive in the manufacturing of aluminum and in electrolysis.
  • Some intriguing discoveries have revealed that aluminum fluoride has a wide range of applications in a number of sectors and activities. It is, for example, a key component in the manufacture of fluoroaluminate glass.
  • Fluoroaluminate glass is used in a variety of optical fiber applications, including medical and fiber-optic imaging.
  • Aluminum fluoride is widely used in ceramics, where it is the primary chemical constituent for final goods. 

Frequently Asked Questions

Is AlF3 ionic or covalent?

Aluminum fluoride is a covalent compound because the Al-F bonds are covalent bonds. Aluminum has a valency of three, it is sharing these three electrons with each fluorine atom.

What is the name of AlF3?

AlF3 compound name is aluminum fluoride. This compound is made of one aluminum atom and three fluorine atoms. The Al-F bonds are covalent bonds.

Where is aluminum fluoride found?

A mineral by the name Rosenbergite is the main source of aluminum fluoride in nature. This mineral’s crystal structure lies someplace between tetragonal and dipyramidal.

What does aluminum fluoride do?

Aluminum fluoride is mainly used in the production of metal aluminum. It is also used in the manufacturing of aluminum foil, which is a popular consumer product that is used when cooking both indoors and outdoors.

Is AlF3 a binary compound?

A binary compound is a compound that is composed of only two different elements. There are only two elements in AlF3: aluminum and fluorine. So, it is a binary compound.

Why is AlF3 not aluminum trifluoride?

Aluminum trifluoride is the systematic name of AlF3. Since, it is common knowledge that the aluminum atom has a valency of three, meaning it can form three bonds with other molecules. Adding the tri- prefix is unnecessary since one can automatically deduce that aluminum fluoride has three F atoms bonded to one Al atom.

Sample Questions 

Question 1: Why is aluminum fluoride ionic?


Aluminium fluoride is classified as an ionic compound due to the larger electronegativity gap between the two atoms that comprise the complex. 

Question 2: In a single formula unit, how many electrons are transported between aluminum and fluoride?


In the formation of the ionic compound aluminium fluoride, aluminium contributes three outer electrons to three fluorine atoms, resulting in a triple positive aluminium ion and three single negative fluoride ions. 

Question 3: Why is the melting point of aluminum fluoride so high?


The melting point of aluminium fluoride is higher than that of aluminium chloride. This is due to its ionic character, as compared to Aluminium Chloride’s covalent character. The cation in both compounds is the same, but the anion size varies. 

Question 4: Why is aluminum iodide covalent when aluminum fluoride is ionic? 


Aluminium iodide is covalent because the electron pair is easily driven away from the iodide ion,  Aluminium fluoride, on the other hand, is ionic because the aluminium ion cannot adequately polarise the tiny fluoride ion to create a covalent bond.

Question 5: Is aluminum fluoride water soluble?


Aluminum fluoride, Trihydrate is water soluble but insoluble in most organic solvents, whereas Aluminum fluoride, Anhydrous is insoluble in water. Aluminum fluoride is primarily used as an additive in the production of aluminium and by electrolysis. 

Question 6: Why is AlCl3’s melting point lower than AlF3‘s?


AlF3 has a higher melting point than AlCl3 because it is an ionic compound, whereas AlCl3 is a covalent compound with a polar covalent bond. Ionic compounds have a higher melting point than covalent ones because ionic bonds are stronger than covalent bonds. 

Question 7: What kind of bond would aluminum and fluoride form?


In the ionic compound aluminium fluoride, the aluminium donates its three outer electrons to three fluorine atoms, resulting in a triple positive aluminium ion and three single negative fluoride ions in terms of electron arrangement. 

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