ALUMINIUM HYDROXIDE

Aluminium Hydroxide Al (OH)₃ is an amorphous white solid. It is an amphoteric compound dissolved both in acids and alkalis. It forms Aluminic acid. It has a hexagonal structure. In reaction with acids, it acts as Bronsted –Lowry base, thus yields a salt by neutralizing the acid. When it reacts with bases, it acts as Lewis’s acid. It is an odourless salt. Aluminium Hydroxide occurs in nature. It has a pH of 10.09. Due to its acidic nature, it is soluble in mineral acid solution. At high temperature, up to 220°C it decomposes into non-flammable water and aluminum oxide. This is an endothermic reaction thus Aluminium Hydroxide absorbs energy.

CAS NO :- 21645-51-2

USES AND APPLICATIONS FOR ALUMINIUM HYDROXIDE

• It is used as an antiperspirant and dentifrices.
• It is widely used in the formation of chemicals and medicines.
• It is used in the pottery, glass, and fabric industry.
• It is essential for polyesters, fire retardants, PVC, and rubber.
• It has its applications in the paper and printing industries.
• It is used in food packaging.
• It is used as an antacid (neutralizes excess amount of acid).
• It is used for the relief of upset stomach and heartburn.

PREPARATION

Solution of Sodium Carbonate and solution of Potash alum are added to form Aluminic Acid. Solutions are heated before adding. Aluminium Hydroxide is precipitated. After that, it is washed with hot water so that no sulphate ions are attached to this amorphous mineral.

CHEMICAL PROPERTIES

• It is insoluble in ethanol and water.
• It is stable at 25°C.
• It absorbs protein well.