Ruthenium is the lightest and least “noble” of all platinum group metals. It is perhaps the most “multivalent" element (nine valence states are known). Despite more than half a century of research history, he still poses many questions and problems before modern chemists. So what is ruthenium as a chemical element? For a start - a little digression into history.
Mysterious and rich
The name and history of the discovery of ruthenium is inextricably linked with Russia. At the very beginning of the XΙX century, the world community was excited and worried about the news that the richest deposits of platinum were discovered in the Russian Empire. It was rumored that in the Urals this precious metal could be mined with an ordinary shovel. The fact of the discovery of rich deposits was soon confirmed by the fact that Russian Finance Minister E. F. Kankrin sent the highest decree on minting platinum coins to the St. Petersburg Mint. In the following years, about one and a half million coins (3.6 and 12 rubles) were put into circulation, for the production of which 20 tons of precious metal were spent.
"Discovery" Ozanne
The professor of the University of Dorpat-Yuryev (now Tartus) University Gottfried Ozann took up the study of the composition of the Ural precious ore. He came to the conclusion that platinum is accompanied by three unknown metals - semiran, polynomial and ruthenium - whose names were given by Ozanne himself. By the way, he named the third in honor of Russia (from the Latin Ruthenia).
Ozann’s colleagues throughout Europe, led by the most influential Swedish chemist Jens Berzelius, were very critical of the professor’s message. In an attempt to justify himself, the scientist repeated a series of his experiments, but failed to achieve previous results.
Two decades later, chemistry professor Karl Karlovich Klauss (Kazan University) became interested in the work of Ozanne. He sought permission from the finance minister to receive a few pounds of coin production from the Mint’s laboratory for re-research.
Kazan chemical element ruthenium
The Russian academician A.E. Arbuzov noted in his writings that in order to discover a new element in those times, chemists needed extraordinary hard work and perseverance, observation and insight, and most importantly, a subtle experimental flair. All of the above qualities were inherent in the highest degree to the young Karl Klauss.
The scientist’s research was also of practical importance - the additional extraction of pure platinum from ore residues. Having developed his own experimental design, Klauss fused the ore material with nitrate and extracted soluble elements: osmium, iridium, and palladium. The insoluble portion was exposed to a mixture of concentrated acids ("aqua regia") and distillation. In the precipitate of iron hydroxide, he discovered the presence of an unknown metal and first isolated it in the form of sulfide, and then in pure (about 6 grams). The professor retained the element proposed by Ozanne - ruthenium.
Open and prove
But as it turned out, the story of the discovery of the chemical element ruthenium was just beginning. After the publication of the results of the study in 1844, a hail of criticism fell upon Klauss. The findings of an unknown Kazan scientist were skeptically accepted by the world's leading chemists. Even sending a sample of a new element to Berzelius did not save the situation. According to the Swedish master, ruthenium Klauss was only a "breakdown of unclean iridium."
Only the outstanding qualities of Karl Karlovich as a chemical analyst and experimenter and a series of additional studies allowed the scientist to prove his case. In 1846, the discovery received official recognition and confirmation. For this work, Klauss was awarded the Demidov Prize of the Russian Academy of Sciences in the amount of 10 thousand rubles. Thanks to the talent and perseverance of the Kazan professor, ruthenium joined the ranks of platinoids - the first element discovered in Russia (and today, unfortunately, the only one in the national chemical school).
Further research
The main problem of studying the chemical and physical properties of ruthenium is the extremely limited content of this metal in the earth's crust. For example, in the waste of platinum production (Clauss's working material) its content is about 1%. Most chemical scientists recognize ruthenium as an extremely unfavorable substance to study. The abundance of deadlocks often forces researchers to curtail or suspend their work.
All his life he devoted the study of the properties of the "uncomfortable" metal and its compounds, the Soviet scientist S. M. Starostin. The main result of the chemist's activity is conclusions about the properties of ruthenium nitroso complexes and the associated difficulties in separating pure metal from the accompanying uranium and plutonium. What is ruthenium as a chemical element?
Physical properties
Ruthenium is a metal whose color, depending on the method of preparation, ranges from gray-bluish to silver-white. Some physical characteristics of the chemical element of ruthenium make it a unique substance. Along with high brittleness (crystals, even by hand, are easily ground into powder), ruthenium has an extreme hardness of 6.5 on a ten-point mineralogical hardness scale (Mohs scale). Perhaps the lightest of the platinum group metals. Density - 12.45g / cm 3 . Very refractory - the temperature of the transition to a liquid state is 2334 ° C. When melting in an electric arc, simultaneous evaporation of the metal is observed. During high-temperature annealing in the open air, the element “disappears” in the form of tetroxide.
Ruthenium is classified as a group of superconductors. The metal shows zero resistance when cooled to 0.47 K. This property is of great importance from a scientific and practical point of view. As platinum ruthenium is a very interesting precious metal.
Ru element
The properties of the Kazan metal are in many ways typical of representatives of the VΙΙΙ (platinum) group. Ruthenium is a chemical element of the periodic table with atomic number 44, which is highly inert. It has 7 stable natural and 20 artificial isotopes with mass numbers from 92 to 113.
At normal temperature it is not subject to oxidation and corrosion, to the effects of acids and alkalis. When heated above 400 ° C, it reacts with chlorine, at 930 ° C - with oxygen. With some metals, the ruthenium chemical element forms stable alloys called intermetallic compounds.
In numerous compounds, it exhibits a valence from zero to eight. The most important include ruthenium dioxide and tetroxide, RuS 2 sulfide and RuF 5 fluoride.
In its pure metal form, it possesses the properties of a catalyst with high selectivity, which allows it to be used for the synthesis of a wide variety of organic and inorganic substances. Serves as the best sorbent for hydrogen.
Spread in nature
The chemical element of ruthenium is characterized by extreme rarity and dispersion in nature. In the natural environment, it forms the only known mineral - laurite. This solid is in the form of small iron-black octahedra. The richest and most famous deposit is located on the platinum placers of the island of Borneo (Kalimantan). In Russia, developments are underway in the Middle and Southern Urals, on the Kola Peninsula, in the Krasnoyarsk and Khabarovsk Territories.
In all other natural compounds, the amount of ruthenium does not exceed 0.1%. Traces of the metal were found in some copper-nickel ores and acidic igneous rocks. The ability to concentrate and accumulate ruthenium is possessed by some plants, among which representatives of the legume family stand out.
The total content of the element in the earth's crust, according to experts, does not exceed 5,000 tons.
Industrial receipt
The ruthenium element is considered noble, and the main source of metal is dump platinum. The undisputed leader in the extraction of ruthenium (like platinum) is the Republic of South Africa. The development and production of this metal is also carried out by Russia, Canada and Zimbabwe. By the way, the last country ranks second in the world in explored reserves of platinoids.
The amount of ruthenium supplied to the market ranges from 17 to 20 tons per year. The production cycle for the production of an element lasts about 6 weeks and is a continuous chain of thermochemical reactions following one after another.
A technology has been developed for the production of ruthenium by neutron irradiation of isotopes of radioactive technetium. But it should be noted that the selection of pure and stable metal, due to its chemical properties, unpredictability and lack of knowledge, remains a pipe dream.
Areas of use
Although all the properties of the noble metal in ruthenium are fully present, the element was not widely used in the jewelry industry. It is used only to strengthen alloys and give expensive jewelry more strength.
By the amount of ruthenium consumed, the industrial sectors are arranged in the following order:
- Electronic.
- Electrochemical.
- Chemical.
The catalytic properties of the element are in great demand. It is used in the synthesis of hydrocyanic and nitric acids, in the preparation of saturated hydrocarbons, glycerol and the polymerization of ethylene. In the metallurgical industry, ruthenium additives are used to increase anticorrosion properties, impart strength, chemical and mechanical resistance to alloys. The radioactive isotopes of ruthenium often help scientists conduct research.
Many compounds of the element have also found application as good oxidizing agents and dyes. In particular, chlorides are used to enhance luminescence.
Biological significance
Ruthenium has the ability to accumulate in the cells of living tissues, mainly muscle cells (the only one of the platinum group metals). It can provoke the development of allergic reactions, have a negative effect on the mucous membrane of the eyes and upper respiratory tract.
In medicine, a noble metal is used as a means to recognize affected tissues. Medicines based on it are used to treat tuberculosis and various infections that affect the skin of a person. For this reason, the use of the ability of ruthenium to form strong nitroso complexes in the fight against diseases associated with an excessive concentration of nitrates in the human body (hypertension, arthritis, septic shock and epilepsy) looks very promising.
Who's guilty?
More recently, scientists in Western Europe have seriously worried the public with a report that the content of the radioactive isotope of ruthenium Ru 106 is growing over the continent. Experts completely exclude self -formation in the atmosphere. As well as emergency release from nuclear power plants, since then radionuclides of cesium and iodine would have been mandatory in the air, which is not confirmed by experimental data. The impact of this isotope on the human body, like any radioactive element, leads to the irradiation of tissues and organs, the development of cancer. Possible sources of pollution, according to Western media, are located in Russia, Ukraine or Kazakhstan.
In response, a representative of the Communications Department of Rosatom said that all state-owned enterprises worked and are operating normally. The International Atomic Energy Agency (IAEA), in its opinion, based on its own monitoring data, called all the accusations against the Russian Federation baseless.