Preparation of Potash Alum

 

Aim : To prepare and submit pure product of Potash Alum and calculate the % yield 

Apparatus & Chemical Required: 

Beaker 100ml, glass rod, funnel, filter paper, distilled water, Potashium Sulphate, aluminum sulphate.

Discussion & Principle:

Potash alum is prepared by dissolving an eqimolar mixture of hydrated aluminium sulphate and potash sulphate in minimum amount of water containing a little sulphuric acid and then subjecting the resulting solution to the crystallization, when octahydral crystals of potash alum is separate out.

Reaction: 

Preparation: 

• Take 250ml beaker. Wash it with water and then transfer 2.5g potassium sulphate crystals to it. Add about 20ml of water. Stir to dissolve the crystals. Warm it if required.
• take other 250ml beaker, wash it with water and then transfer 10gm aluminum sulphate crystals to it. Add about 20ml of water and 1 ml of dil.sulphuric acid heat for 5mins.
• Mix both the solution in a china dish and place the china dish on wire gauze placed over a burner
• Filter the residue and dry it in air.

Uses :

• It is used for water purification and also as antiseptics.
• It can be used as astringent 
• It can be used as deodorant 

 Calculation:

Molecular weight of Al₂(SO₄)₃=342.15 g/mol

 Molecular weight Potash alum = 474.39 g/mol

 % yield =

Report: 

The percentage yield of prepared zinc chloride was found to be ____%