The shiny and ductile metal palladium is highly valued in jewelry, used in industry, medicine and other fields. Its arsenal contains many interesting properties that make it a very useful element. What is he capable of? Read about the melting temperature of palladium, its physical, chemical and other characteristics in our article.
History and Background
The chemical element palladium belongs to noble metals and in the Periodic System is numbered 46. It was discovered in 1802 and was named after the asteroid Pallas, which was discovered in the same year. The asteroid itself was named for the character of Greek mythology - the daughter of the sea king Triton and sister of the goddess Athena.
As it usually happens, the discovery of palladium occurred by chance and completely unplanned. The English chemist William Wollaston, who managed to find him, did not hope to find a new element. He was engaged in the purification of platinum from impurities of mercury and gold, and at one stage of the work he received a pink precipitate. None of the components of the solution could give such a shade, so the scientist suggested the presence of impurities unknown to him.
Wollaston tried to dissolve the precipitate in aqua regia, added potassium cyanide to it, heated it and gave in to other tests. In the end, he isolated two new components from it - palladium and rhodium, which was a real breakthrough in his career.
Palladium Properties: Melting Point, Density, Hardness
In appearance, palladium is often compared with platinum and silver. Just like these metals, it is painted in a light gray shade and has a strong sheen. In terms of density, it stands in an intermediate position between them, surpassing silver and slightly not reaching platinum. So, for one cubic centimeter, about 12.02 grams of substance are accounted for.
Palladium is very soft and ductile. It is easily amenable to various types of processing. Interestingly, with a cold finish it only becomes harder, but if it is burned, the softness returns. The hardness of the substance also increases with the addition of nickel, mercury, rhodium and cobalt. The melting point of palladium is 1552 degrees Celsius, at 3980 degrees the metal boils.
In addition to the ordinary form, it has about 130 isotopes, only six of them are stable: 102 Pd, 104 Pd, 105 Pd, 106 Pd, 108 Pd and 110 Pd. The palladium-103 isotope is artificial. It is obtained by irradiation of rhodium-103 and is used to treat cancer. Palladium-107 is considered the most stable of all unstable isotopes; its half-life is 1 million years.
One of the platinoids
The palladium element is included in the platinum group group together with iridium, osmium, ruthenium, rhodium and, directly, platinum. All of them are noble transition metals and often coexist in natural deposits. Platinoids are characterized by light shades, relative refractoriness, and inertness in chemical reactions.
The most active among them is palladium. It is able to dissolve in concentrated nitric and sulfuric acids, interact with aqua regia at room temperature, and react to wet bromine and chlorine. If it is heated, then reactions with fluorine, silicon, selenium and arsenic are possible. In water, ammonia solution and dilute acids, the metal remains as it is and does not react.
Palladium has the lowest melting point among all platinoids. The same can be said about its boiling. It is quite stable in air and does not lend itself to corrosion up to 300 degrees Celsius. When heated stronger, it becomes darker and becomes covered with a thin oxide film, which decomposes at temperatures above 850 degrees.
Application
The beautiful appearance and high stability of palladium make it possible to use it in jewelry. Unlike silver, it does not darken over time, does not wear out and does not need special care. In jewelry it is used independently, as a frame for precious stones or in alloys with an aurum element to produce a separate type of material - “white gold”.
The inert properties of palladium are used to give other metals resistance. Mixing with it, titanium is able to withstand the action of caustic substances. Metal is used for the manufacture of chemical glassware that would not give in to corrosion and would not dissolve in an aggressive environment. For the same purpose, they cover various parts for aerospace and military equipment, as well as medical instruments.
In the automotive and chemical industries, it is used as a catalyst. In cars, with its help, exhaust gases are burned, which significantly reduces their ingress into the external environment.
Mining, price and location
Palladium is considered a rare metal; it contains 1 · 10 –6 % by mass in the earth’s crust. This is not the smallest amount, but finding it in the form of nuggets is very difficult. Approximately 98% of the extracted volume is extracted from primary deposits, where palladium is a part of minerals. Most often, it is present in potarite, ferroplatinum, bragette, iridic and palladium platinum, and zyagintsevite.
The main amount of metal is mined in copper-nickel mines. The largest such deposits are located in Russia. Large palladium deposits are also found in platinum deposits in South Africa. Then follow mines in the USA, Canada, Austria and Columbia.
The cost of palladium in the precious metal market is usually higher than platinum. They are often traded on exchanges, and in the banking systems of some countries of the world, it can serve as the currency for opening an account.