LAB 5

LAB 5

Introduction

Alum or potassium alum (alum) or simply potash alum is the sulphate double aluminum and potassium. Its formula is KAl(SO4)2. It is commonly found in form dodecahydrate as KAl (SO4)2.12(H2O). It presents also had twenty four molecules of water of hydration, KAl (SO4)2· 24(H2O).

The potassium alum crystallizes in octahedral regular flat edges, and is very soluble in water. The solution becomes red to blue litmus (pH 5% = 3.0 to 3.5) and is an astringent. When heated to redness it gives a porous mass, which is known as "burnt alum" melts at 92°C, completely dissolving in its own ...