Experiment No. 12 Preparation of inorganic pharmaceuticals - Potash Alum

AIM: To prepare and submit Potash alum (K2SO4. Al2(SO4)3 .24 H2O)

 

REFERENCES

1.        Singh H.R., Kapoor V.K. “Practical Pharmaceutical chemistry”, Vallabh Prakashan, Ed I^st, 2008, pp 59-60

2.        Chatwal G.R, “Pharmaceutical chemistry inorganic” Himalaya publishing house, Ed 5^th, 2010, pp 223-224.

 

REQUIREMENTS

Chemical required: - Potassium sulphate, Aluminium sulphate.

Apparatue required: - Beaker, funnel, glass rod & Measuring cylinder.

 

 THEORY

Synonyms: Alum

Chemical formula: (K2SO4. Al2(SO4)3 .24 H2O)

Molecular weight: 948.77

Alums are sulphates of a univalent metal and a trivalent metal.

Theory:

Alum is also used as an astringent. Astringents are the compound which brings about protein precipitation. The protein precipitation action of an astringent is due to presence of metallic ion having large charge. The metal would form complex with various polar groups present on the protein. In general astringents perform following function .

Stop the bleeding by coagulation of blood and constrict the small blood capillaries Antiperspirant action by decreasing secretion of perspiration by reducing pore size of the  skin.

Anti-infammatory action by decreasing supply of blood to the tissue.

Antimicrobial action by protein precipitation mechanism.

It is prepared by adding a concentrated solution of potassium sulphate to a hot solution of aluminium sulphate.

                        

  Al2(SO4)3 + K2SO4 + 24 H2O → 2K2SO4.Al2(SO4)3. 24H2O

 PROCEDURE

Take 6.3 g of potassium sulphate (K2SO4) and dissolved in 10 mL of dissolved water &

2.5 g of Aluminium sulphate Al2(SO4)3, is dissolved in water separately. Heat both the solution and Mix slowly with continous stirring.

It is cooled in ice bath for half an hour.

Crystals of potash alum separates out, generally crystals are octahedral in shape. Filter the solution and dry alum.

 

PROPERTIES

·        Alum occurs as large colorless crystal.

·        It is odorless with a sweet astringent taste. 

·        Its solution is acidic to litmus.

·       Alum is freely soluble in water but slowly dissolve in glycerin and insoluble in 

alcohol 

USES

·      Alum is used as an aftershave due to its astringent property. It can be rubbed on freshly shaved face.

·         Used in the preparation of cosmetics like deodorant

·         Alum powder is used to reduce and prevent bleeding due to small cut.

·         Used as a mouthwash & tooth powder.

·         Used as a mordant in dying industry. Used as protein precipitant.

·         Used in fire extinguisher due to its flame retardant property 

 RESULT

Potash alum was prepared and submitted.

YouTube Video - Preparation of Potash alum