Nickel

Nickel: the essentials

 Brief description: nickel is found as a constituent in most meteorites and often serves as one of the criteria for distinguishing a meteorite from other minerals. Iron meteorites, or siderites, may contain iron alloyed with from 5 to nearly 20% nickel. The USA 5-cent coin (whose nickname is "nickel") contains just 25% nickel. Nickel is a silvery white metal that takes on a high polish. It is hard, malleable, ductile, somewhat ferromagnetic, and a fair conductor of heat and electricity.

Nickel carbonyl, [Ni(CO)₄], is an extremely toxic gas and exposure should not exceed 0.007 mg M^-3.

Small and large samples of nickel foil like this, as well as sheet, wire, mesh and rod (and nickel alloys in foil, sheet, wire, insulated wire and rod form) can be purchased from Advent Research Materials via their web catalogue.

Cartoon by Nick D Kim (nearingzero.net, used by permission).

Isolation

Isolation: it is not normally necessary to make nickel in the laboratory as it is available readily commercially. Small amounts of pure nickel can be islated in the laborotory through the purification of crude nickel with carbon monoxide. The intermediate in this process is the highly toxic nickel tetracarbonyl, Ni(CO)₄. The carbonyl decomposes on heating to about 250°C to form pure nickel powder.

Ni + 4CO (50°C) → Ni(CO)₄ (230°C) → Ni + 4CO

The Ni(CO)₄ is a volatile complex which is easily flushed from the reaction vessel as a gas leaving the impurities behind. Industrially, the Mond process uses the same chemistry. Nickel oxides are reacted with "water gas", a mixture of CO + H₂). Reduction of the oxide with the hydrogen results in impure nickel. This reacts with the CO component of the water gas to make Ni(CO)₄ as above. Thermal decomposition leaves pure nickel metal.

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