Aluminium Hydroxide Formula

Aluminium Hydroxide Formula

The Aluminium Hydroxide formula is articulated as Al(OH)3. The hydroxide of aluminium (III) is another way to spell it. An amorphous white powder, Aluminium Hydroxide can be seen in nature. Gibbsite is a mineral that occurs naturally (also called hydrargillite).

Aluminium Hydroxide has a molar mass of about 78.00 g/mol. Ayerite, doyleite, and nordstrandite are other polymorphs of Aluminium Hydroxide. It is an amphoteric oxide.

Aluminium Hydroxide is also utilised in polymer applications as a filler with fire-retardant properties. It is used for these applications because it has high fire retardant qualities, is inexpensive, and is colourless (like other polymers). Magnesium Hydroxide and combinations of Huntite and Hydromagnesite are used similarly. 

Around 180 °C (356 °F) is the decomposition temperature, during which it absorbs a significant amount of heat and releases water vapour. In addition to being a fire retardant, it also works incredibly well as a smoke suppressant in various polymers, such as rubber, polyester, acrylics, ethylene vinyl acetate, epoxies, and PVC.

Aluminium Hydroxide Chemical Formula

Aluminium hydroxide is known by several names, including aluminium acid, aluminium hydroxide, and aluminium (III) hydroxide. It is the chemical word for all metal hydroxides, sulphates, and carbonates, including aluminium.   It may be found in nature as the mineral gibbsite and its polymorphs, including doyleite, nordstrandite, and bayerite.

The chemical formula for aluminium hydroxide is Al(OH)3. Aluminium hydroxide is a white, amorphous powder. It is insoluble in water, but soluble in alkaline and acidic solutions. It can be used to relieve stomach pain, acid reflux, heartburn, and a sour stomach. It can also be used to reduce phosphate levels in those with renal problems. The antacid may also be effective in non-medical applications.

Aluminium Hydroxide Structural Formula

Aluminium hydroxide is an amphoteric chemical that may function as both an acid and a base. It exists in acidic solutions as the aluminium ion (Al3+) and the hydroxide ion (OH-). It appears in basic solutions as the aluminium hydroxide ion, Al(OH)4-. The aluminium hydroxide ion is tetrahedral, having a bond angle of 116.5° between Al-O-Al. Aluminic hydroxide has a typical metal hydroxide structure with hydrogen bonds.
It is composed of two layers of hydroxyl groups and two layers of aluminium ions, which fill two-thirds of the octahedral holes formed between the two layers.

Gibbsite is an amphoteric mineral that functions as a Bronsted-Lowry base to produce salt by absorbing hydrogen ions and neutralizing the acid. Here is the Reaction,

3HCl + Al(OH)₃ → AlCl₃ + 3H₂O

In bases, it acts as a Lewis acid. It reduces the hydroxide ions of an electron pair. Another reaction is,

Al(OH)₃ + OH^– → Al(OH)₄^– 

Aluminium Hydroxide Preparation

Aluminium hydroxide, which is widely used in industry, is produced using the Bayer method. The process involves dissolving bauxite in a sodium hydroxide solution at temperatures ranging from 0 to 270°C. After the garbage is removed, the sodium aluminate solution is left to precipitate. As a result, the precipitate produced is aluminium hydroxide.
Calcination can convert aluminium hydroxide into alumina or aluminium oxide.

Bayer Process Reactions

• First: Al₂O₃.2H₂O + 2 NaOH → 2 NaAlO₂ + 3 H₂O
• Second: NaAlO₂ + 2 H₂O → Al(OH)₃ + NaOH
• Third: 2 Al(OH)₃ → Al2O₃ + 3 H₂O

Aluminium Hydroxide Properties

Physical Properties of Aluminium Hydroxide:

The following are the physical properties of aluminium hydroxide:

• Aluminium hydroxide appears as a white amorphous powder.
• Aluminium hydroxide has a melting point of around 573 K.
• Aluminium hydroxide is insoluble in water, but it dissolves in alkalis and acids.
• Solid aluminium hydroxide has a density of around 2.42 g/cm3.

Chemical Properties of Aluminium Hydroxide:

• Aluminium hydroxide is an amphoteric compound.
• It may act as both an acid and a base.
• Aluminium hydroxide acts as a Bronsted-Lowry base in acids.
• As a result, it neutralises the acid-forming salt and water that comprise the final product.

Aluminium Hydroxide Uses

• Aluminium hydroxide is used as a flame retardant in plastics.
• Used as an antacid.
• Used in aluminium Hydroxide gel.
• Used to manufacture activated alumina.
• Used as a filler in cosmetics.
• Used as a chemical intermediate.
• Used as a soft abrasive for plastics.
• Used in glass additive to increase resistance to thermal shock.
• Used in waterproofing fabrics.
• Used in the manufacturing of glass.