Palladium

Palladium . Chemical element, symbol Pd, atomic number 46 and atomic weight 106.4. It is a white and very ductile metal similar to platinum, which is followed in abundance and importance, discovered by William Hyde Wollaston , in England in 1803 . Its name comes from the asteroid “Palas”, discovered around the same time and from the Greek goddess of wisdom and intelligence applied to any art or science, “Pallas”.

Summary

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  • 1 Natural state
  • 2 Compounds
  • 3 Isotopes
  • 4 Applications
  • 5 Health effects
  • 6 Sources

Natural state

Wollaston discovered palladium in a crude platinum ore from South America. The mineral was dissolved in aqua regia (a mixture of hydrochloric and nitric acid), neutralizing the excess acid with sodium hydroxide and, precipitating the platinum by treating it with ammonium chloride, originating ammonium chloroplatinate. The palladium was removed in the form of palladium cyanide by treating it with mercuric cyanide. Palladium was obtained by heating palladium cyanide.

Compounds

Palladium chlorides and compounds related to it are the most important. Palladium chloride, PdCl2, is used in electrodeposition , and related chlorides are used in the refining cycle and as sources of pure palladium-sponge, in thermal decomposition processes. Palladium monoxide, PdO, and dihydroxide, Pd (OH) 2, are used as sources of palladium catalysts. Sodium tetranitropaladate, Na2Pd (NO2) 4, and other complex salts are used as bases in electroplating.

Isotopes

Palladium is naturally made up of six isotopes. The most stable radioisotopes are 107 Pd with a half-life of 6.5 million years, 103 Pd with a half-life of 17 days, and 100 Pd with a half-life of 3.63 days. Eighteen other radioisotopes have been characterized with atomic weights ranging from 90.94948 (64) ( 91 Pd) to 122.93426 (64) ( 123 Pd). Most of these have a half-life of less than half an hour, except for 101 Pd (half-life 8.47 hours), 109 Pd (half-life: 13.7 hours), and 112 Pd (half-life: 21 hours).

Applications

  • Finely divided palladium is a good catalyst for hydrogenation / dehydrogenation reactions.
  • Alloyed, it is used in jewelry. The white gold is gold alloyed with palladium that discolors.
  • Palladium, silver and copper alloys are very hard and stable to corrosion . They are used in dentistry (prosthetics), watchmaking, surgical instruments and electrical contacts, crucibles, etc.
  • It is used to make electrical contacts.
  • It is used to purify hydrogen gas.
  • Palladium chloride has application for the detection of carbon monoxide.

Health effects

May cause skin, eye, or respiratory tract irritation. May cause skin hypersensitivity. Liquid can cause skin and eye burns. If ingested, do not induce vomiting, if conscious give water, milk. In case of contact, rinse eyes or skin with plenty of water. Palladium compounds are very rarely found. All palladium compounds should be considered highly toxic and carcinogenic. Palladium Chloride is toxic, and harmful if swallowed, inhaled, or absorbed through the skin. It causes damage to the marrow, liver and kidneys in laboratory animals. Irritating. However, palladium chloride was initially prescribed as a treatment for tuberculosis at the dose of 0.065 g per day (approximately 1 mg / k) without too many negative side effects.

 

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