Lead

Lead: the essentials

 Brief description: lead is a bluish-white lustrous metal. It is very soft, highly malleable, ductile, and a relatively poor conductor of electricity. It is very resistant to corrosion but tarnishes upon exposure to air. Lead pipes bearing the insignia of Roman emperors, used as drains from the baths, are still in service. Alloys include pewter and solder. Tetraethyl lead (PbEt₄) is still used in some grades of petrol (gasoline) but is being phased out on environmental grounds.

Lead isotopes are the end products of each of the three series of naturally occurring radioactive elements.

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

Isolation

Isolation: there is usually little need to make lead metal in the laboratory as it is so cheap and readily available. Lead is isolated from the sulphide, PbS. The process involves burning in a restricted air flow followed by reduction of the resulting oxide PbO with carbon.

PbS + ³/₂O₂ → PbO + SO₂

PbO + C → Pb + CO

PbO + CO → Pb + CO₂

This gives lead usually contaminated with metals such as antimony, arsenic, copper, gold, silver, tin, and zinc. A fairly complex process is used to strip out these impurities.

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