Iron(III) ammonium sulfate
Iron (III) ammonium sulphate

A solid crystalline salt with the formula
NH₄Fe(SO₄)₂.12H₂O

It is commonly called ferric alum and is an example of a hydrated salt, i.e. it crystallises with extra molecules of water.

Note :
modern textbooks write "sulfate" but older ones write "sulphate".

Table of contents