Description
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Palladium is a rare transition metal that has a silvery white color in its natural solid state. It has the unique ability to absorb 900 times of its own volume in hydrogen, and will dissolve slowly in sulfuric, nitric, and hydrochloric acid. Palladium has an atomic weight of 106.42, a melting point of 2830.82 °F, and a boiling point of 5365 °F. Palladium is commonly used as a catalyst for chemical reactions, and as a component in some jewelry.
Isolation
Palladium has been found in its natural free state in nature, but this is very rare. Most often palladium occurs in ores that contain platinum and gold; isolating palladium is a multi-step process.
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The complexity of palladium isolation is due to the fact that palladium must be separated from the gold and platinum that it occurs with. Isolation of palladium is not performed on a small laboratory basis because of the difficulties associated with its isolation processes. The first step of the process involves treating the ore with a compound containing hydrochloric acid and nitric acid. The resulting mixture contains a solution of gold, platinum, and palladium in the form of H2PdCl4.
Iron chloride is added to the solution of metals to remove the gold elements; the platinum is removed the solution through a precipitate by treating the remaining solution with ammonium chloride. Palladium is left in the solution in the form of H2PdCl4; this form of palladium is treated with ammonium hydroxide and hydrochloric acid to precipitate out the palladium in the form of PdCl2(NH3)2. Pure palladium metal is then isolated from this complex through burning off the chlorine, nitrogen, and hydrogen.