Demonstration of the intermediate position of cobalt between iron and

AUGUST, 1953

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DEMONSTRATION OF THE INTERMEDIATE POSITION OF COBALT BETWEEN IRON AND NICKEL ERNST M. GOLDSTEIN Metal Powder & Chemical Works, Newark, New Jersey

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bxidizability of ferrous, cobaltous, and nickelous hydroxides, together with the increasing color deepness of the oxidation products, can be used to demonstrate that cobalt is intermediate in its properties between iron and nickel. (1) Iron. Take a solution containing Fe++ ions and add a solution of alkali hydroxide. The white precipitate of Fe(OH)2formed a t first is almost instantaneously oxidized by air, converting it into reddish-brown Fe(OH),, no additional oxidizing agent being required.

(2) Cobalt. Precipitate in the same way a solution containing Co++ ions. A blue basic hydroxide is formed, changing very soon to pink colored CO(OH)~. This hydroxide is very slowly oxidized by air to the dark brown Co(OH),, hut immediately by hydrogen peroxide. (5) Nickel. A solution containing Ni++ ions gives with alkali hydroxide solution an apple-green precipitate of Ni(OH),, not oxidized by air or hydrogen peroxide. Oxidation to the black nickelic state can be brought. about through the addition of bromine.