An amphoteric substance is one that can behave as a Lewis acid and a Bronsted base, iron is not amphoteric. The best examples of substances behaving as an acid and a base are found with metal hydroxides such as aluminum hydroxide and zinc hyhroxide. Only certain cations show amphoteric behavior, for example if NaOH is added in small amounts to solutions of Fe3+ and Al3+ both will initially form precipitates (rust colored iron hydroxide and white aluminum hydroxide). Because Al(OH)3 is an amphoteric hydroxide and Fe(OH)3 is not, adding more NaOH will redissolve the Al(OH)3 and leave Fe(OH)3 as an insoluble solid. Commonly encountered cations that form amphoteric hydroxides are Al3+, Cr3+, Zn2+, Pb2+, Sn4+ and Sb3+. (Source:http://employees.oneonta.edu/kotzjc/LAB/Complexation.pdf pages 28-29)
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