Video: Iron(III) ion as an acid
Iron(III) ion acts as a Brønsted-Lowry acid as is shown by the pH paper test. Also, the brownish color of the solution is characteristic of the hydroxy speceies as the hexaquairon(III) ion is actually pale purple.[Fe(OH2)6]3+(aq) + H2O(l) ? H3O+(aq) + [Fe(OH)(OH2)5]2+(aq)