Palladium is a chemical element with symbol of Pd and,an atomic number of 46, is a rare element and has a lustrous silver appearance. Discovered by William Hyde Wollaston in the year 1803. The metal was named after asteroid Pallas of the Greek goddess Athena. Pd is extremely ductile and easily worked. It is not tarnished by the atmosphere at ordinary temperatures. Thus, the metal and its alloys serve as substitutes for platinum in jewelry and in electrical contacts; the beaten leaf is used for decorative purposes.
Relatively small amounts of palladium alloyed with gold yield the best white gold. It is used also in dental alloys. The chief use of palladium, however, is in automobile catalytic converters; the palladium serves as a catalyst to convert polluting hydrocarbons, carbon monoxide, and nitrogen oxide in the exhaust to water, carbon dioxide, and nitrogen. It is coatings, electrodeposited or chemically plated, have been used in printed-circuit components, and palladium is also used in multilayer ceramic capacitors.
Uses of Palladium
- The metal serves as a catalyst in many chemical processes like hydrogenation, petroleum cracking, and dehydrogenation.
- Pd is a Lindlar catalyst and sometimes referred to as Lindlar Palladium.
- Used in electrodes and also being a major component for multi-layer ceramic capacitors.
- Being an absorbent of hydrogen, used for storage of the same.
- Used for jewelry making since time immemorial.
- Used by photographers in make fine art with black and white prints using palladium salts.
Characteristics of Pd
- Pd is a soft silver-white metal that resembles platinum. It is the least dense and has the lowest melting point of the platinum group metals. It is soft and ductile when annealed and is greatly increased in strength and hardness when cold-worked.
- It dissolves slowly in concentrated nitric acid, in hot, concentrated sulfuric acid, and when finely ground, in hydrochloric acid. It dissolves readily at room temperature in aqua regia.
- It does not react with oxygen at standard temperature (and thus does not tarnish in air). Palladium heated to 800 °C will produce a layer of palladium(II) oxide (PdO). It may slowly develop a slight brownish coloration over time, likely due to the formation of a surface layer of its monoxide.