Ferric alum, also known as ammonium iron(III) sulfate, is a double salt with the chemical formula NH₄Fe(SO₄)₂·12H₂O. It is a crystalline compound that is soluble in water.  

Ferric alum has a wide range of applications, including:

• Water treatment: It is used as a coagulant to remove turbidity and impurities from water.  

• Textile industry: It is used as a mordant in dyeing processes.  

• Photography: It is used as a developer in photographic processes.
• Etching: It is used as an etching agent for metals.  

• Other applications: It is also used in the production of pigments, inks, and other chemicals.  

   

   

Ferric alum is a versatile chemical with many important industrial and commercial applications.