Aluminium Hydroxide Gel Preparation

What is Aluminium Hydroxide?

Aluminium hydroxide is an inorganic compound made up of aluminum ion and hydroxide ion. It is an amphoteric compound which means it can act as an acid as well as the base. Aluminium hydroxide minerals occur in nature. It holds the property of an antacid. The IUPAC name of the aluminium hydroxide is Aluminium trioxide.


Aluminium Compounds

Aluminium is an inorganic element belonging to the thirteenth group. Aluminium reacts with the nitrogen gas and forms an aluminium nitride

Al + N2 → AlN

Aluminium reacts with the oxygen gas and forms aluminium trioxide also known as alumina.

Al + O2 → Al2O3

Aluminium reacts with the hydrochloric acid and forms aluminium trichloride as a product and hydrogen gas as a byproduct. This aluminium trichloride is used in the preparation of aluminium hydroxide gels. 

Al + HCl → AlCl3 + H2

Aluminium reacts with the dilute sodium hydroxide solution and forms aluminium trihydroxide. This molecule is amphoteric in nature. Therefore, it further reacts with the dilute sodium hydroxide solution and forms sodium meta illuminate aa a product and hydrogen gas as a byproduct. 

Al + NaOH (dil) → Al(OH)3 → Na[Al(OH)4] + H2

Aluminium hydroxide reacts with the water molecules and forms a solution. This reaction can be used to clear drains. This reaction is also used to remove the obstructions from the drainage pipe.

AlCl3 + H2O → [Al (H2O)6]+3 + 3Cl-

Aluminium trichloride reacts with hydrochloric acid and forms white fumes.

AlCl3 + HCl → white fumes


Structure of Aluminium Hydroxide

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Aluminium cation is attracted with three hydroxide anions.


Properties of Aluminium Hydroxide

  • Colour of aluminium hydroxide is white.

  • Its density is 2.43 g/cm3.

  • Its melting point is 300 degrees celsius.

  • Its molar mass is 78.0036.

Aluminium Hydroxide Gel Preparation

Aluminium hydroxide is hydrophobic in nature. Generally, it forms lyophobic solutions. Aluminium hydroxide gel preparation can be done with the hydrolysis of aluminium chloride.

AlCl3 + 3H2O → Al(OH)3 + 3HCl


Step by Step Aluminium Hydroxide Gel Preparation

  • Prepare the 2% aluminium chloride solution (by adding 2g of aluminium chloride in 100 ml water).

  • Add 100 ml distilled water in the conical flask.

  • Boil the water with the help of the wire gauze.

  • Add 10 ml of the above prepared 2% aluminium chloride solution. Add this solution with the help of the dropper of burette. As aluminium compounds are violent in nature.

  • Constantly stir the solution while adding aluminium chloride.

  • Heat the solution until you see a coloured solution. The colour of aluminium hydroxide solution is white.

  • Leave the mixture for cooling at normal temperature.

  • Cooled solution is called aluminium hydroxide gel.

Precaution You Need to keep During Aluminium Hydroxide Gel Preparation

  • Clean the conical flask with a steaming process to avoid any kind of impurities.

  • The byproduct (Hydrochloric Acid) formed in this reaction causes destabilization of the prepared gel. therefore, needs to be removed by the dialysis process.

  • Aluminium chloride solutions need to be added in the dropwise manner.

Uses of Aluminium Hydroxide Gel

  • It is used for treating gastric ulcers.

  • It is used in making vaccines.

  • It is used in cosmetics.

  • It serves as an intermediate compound in various reactions.

  • It is used as a flame retardant.

  • It is used in the manufacturing of certain drugs.

Side Effects of Aluminium Hydroxide Gel

Aluminium hydroxide is generally used as a medicine. But to some people, it shows side effects when consumed. These side effects involves:

  • Diarrhea

  • Muscle weakness

  • Tiredness

  • Loss of appetite

  • Constipation

  • Stomach bloating

Did You Know?

  • Aluminium hydroxide reacts with both acid and base.

  • Aluminium hydroxide is used in coating TiO2 nanoparticles.

  • Aluminum hydroxide is used to reduce phosphate levels in people with certain kidney conditions.

  • Aluminium hydroxide consumption reduces the absorption of the other medicines in the body. Therefore, two-hour gaps before and after taking aluminium hydroxide should be maintained for consuming other medicines with this.

FAQs (Frequently Asked Questions)

Question: What is Aluminium Hydroxide?

Answer: Aluminium hydroxide is an inorganic compound made up of aluminum ion and hydroxide ion. It is an amphoteric compound meaning it can act as an acid as well as base.

Question: Write the Steps to Prepare Aluminium Hydroxide Gel.

Answer: 

Steps for the preparation of aluminium hydroxide gel are:

1) Prepare the 2% aluminium chloride solution (by adding 2g of aluminium chloride in 100 ml water), 2) Add 100 ml distilled water in the conical flask, 3) Boil the water with the help of the wire gauze, 4) Add 10 ml of the above prepared 2% aluminium chloride solution. Add this solution with the help of the dropper of the burette, 5) Keep constantly stirring the solution while adding aluminium chloride.

Heat the solution until you see a coloured solution. The colour of the aluminium hydroxide solution is white, 6) Leave the mixture for cooling at normal temperature, 7) Cooled solution is called aluminium hydroxide gel.