How will you prepare potash alum?

Explanation

The alunite the alum stone is the naturally occuring form and it is `K_(2)SO_(4).Al_(2)(SO_(4))_(3).4Al(OH)_(3)`
When alum stone is treated with excess of sulphuric acid, the aluminium hydroxide is converted to aluminium sulphate. A calculated quality of potassium sulphate is added and the solution is crystallised to generate potash alum. Itis purified by recrystallisation.
`K_(2)SO_(4).Al_(2)(SO_(4))_(3).4Al(OH)_(3)+6H_(2)SO_(4)toK_(2)SO_(4)+Al_(2)(So_(4))_(3)+12H_(2)O`
`K_(2)SO_(4)+Al_(2)(SO_(4))_(3)+24H_(2)OtoK_(2)SO_(4).Al_(2)(SO_(4))_(3).24H_(2)O`