Ruthenium is the lightest and least "noble" of all the platinum group metals. It is perhaps the most "multivalent" element (nine valence states are known). Despite more than half a century of research history, it still poses many questions and problems to modern chemists today. So what is ruthenium as a chemical element? To begin with, a short digression into history.
Mysterious and rich
The name and history of the discovery of ruthenium are inextricably linked with Russia. At the very beginning of the 20th century, the world community was excited and worried by the news that the richest deposits of platinum had been discovered in the Russian Empire. There were rumors that in the Urals the extraction of this precious metal could be carried out with an ordinary shovel. The fact of the discovery of rich deposits was soon confirmed by the fact that the Minister of Finance of Russia, E. F. Kankrin, sent the highest decree on minting coins from platinum to the St. Petersburg Mint. In subsequent 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
Professor of Derpt-Yuryevsky (now Tartu) University Gottfried Ozann started studying the composition of the Ural precious ore. He came to the conclusion that platinum was accompanied by three unknown metals - polynomial, polynomial and ruthenium - the names of which were given by Ozann himself. By the way, he named the third one after Russia (from the Latin Ruthenia).
Ozanne's colleagues throughout Europe, led by the most authoritative Swedish chemist Jens Berzelius, were very critical of the professor's report. In an attempt to justify himself, the scientist repeated a series of his experiments, but failed to achieve the same results.
Two decades later, Professor of Chemistry Karl Karlovich Klauss (Kazan University) became interested in Ozanne's work. He secured the Secretary of the Treasury's permission to take several pounds of leftover coinage from the Mint's lab for retesting.
Kazan chemical element ruthenium
Russian academician A. E. Arbuzov noted in his writings that in order to discover a new element in those days, a chemist needed extreme hard work and perseverance, observation and insight, and most importantly, a subtle experimental flair. All of the above qualities were inherent in the young Karl Clauss to the highest degree.
The scientist's research also had practical significance - additional extraction of pure platinum from ore residues. Having developed his own plan for the experiment, Klauss fused the ore material with s altpeter and extracted soluble elements: osmium, iridium,palladium. The insoluble part 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 isolated it first in the form of sulfide, and then in pure form (about 6 grams). The professor retained the name proposed by Ozann for the element - 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 Clauss. The conclusions of the unknown Kazan scientist were skeptically received by the largest chemists in the world. Even sending a sample of the new element to Berzelius did not save the situation. According to the Swedish master, Clauss's ruthenium was only "a sample of impure iridium".
Only the outstanding qualities of Karl Karlovich as an analytical chemist 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 his 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, the first element discovered in Russia, was added to the ranks of platinoids.
Further research
The main problem in studying the chemical and physical properties of ruthenium is the extremely limited contentthis metal in the earth's crust. For example, in the waste of platinum production (the working material of Clauss), its content is about 1%. Most chemical scientists recognize ruthenium as an extremely unfavorable substance for study. The abundance of impasses often causes researchers to curtail or suspend their work.
Soviet scientist SM Starostin devoted his whole life to studying the properties of "inconvenient" metal and its compounds. The main result of the chemist's activity is the conclusions about the properties of ruthenium nitroso complexes and the difficulties associated with them in separating pure metal from accompanying uranium and plutonium. What is ruthenium as a chemical element?
Physical properties
Ruthenium is a metal whose color, depending on the method of obtaining, ranges from gray-bluish to silver-white. Some physical characteristics of the chemical element ruthenium allow us to consider it a unique substance. Along with high brittleness (crystals are even easily ground into powder by hand), ruthenium has an extreme hardness - 6.5 on a ten-point mineralogical hardness scale (Mohs scale). Perhaps the lightest of the platinum group metals. Density is 12.45g/cm3. It is very refractory - the transition temperature to the liquid state is 2334 ° C. During melting in an electric arc, simultaneous evaporation of the metal is observed. During high-temperature calcination in open air, the element "volatilizes" in the formtetroxides.
Ruthenium is classified as a superconductor. The metal demonstrates zero resistance when cooled to 0.47 K. This property is of great importance from a scientific and practical point of view. As a platinoid, ruthenium is a very interesting precious metal.
Element Ru
The properties of the "Kazan" metal are in many respects typical for representatives of the VΙΙΙ (platinum) group. Ruthenium is a chemical element of the periodic table with atomic number 44, characterized by high inertness. It has 7 stable natural and 20 artificial isotopes with mass numbers from 92 to 113.
Under normal temperature, it is not subject to oxidation and corrosion, acids and alkalis. When heated above 400 ° C, it reacts with chlorine, at 930 ° C - with oxygen. With some metals, the chemical element ruthenium 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, sulfide RuS2 and fluoride RuF5.
In its pure metallic form, it has the properties of a catalyst with a 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 ruthenium is characterized by extremerare and scattered in nature. In its natural environment, it forms the only known mineral, laurite. It is a solid 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). Russia is developing 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 metal have been found in some copper-nickel ores and acid igneous rocks. Some plants have the ability to concentrate and accumulate ruthenium, 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 production
The element ruthenium is considered noble, and the main source of the metal is waste rock from platinum production. The undisputed leader in the extraction of ruthenium (as well as 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 latter country ranks second in the world in terms of explored reserves of platinoids.
The amount of ruthenium supplied to the market ranges from 17 to 20 tons per year. The production cycle for obtaining an element lasts about 6 weeks and is a continuous chain of thermochemical reactions following one after another.
Technology for obtainingruthenium by neutron irradiation of isotopes of radioactive technetium. But it should be noted that the isolation of a pure and stable metal, due to its chemical properties, unpredictability and insufficient knowledge, remains still a pipe dream.
Applications
Although all the properties of the noble metal in ruthenium are fully present, the element has not received wide distribution in the jewelry industry. It is used only to strengthen alloys and make expensive jewelry more durable.
In terms of the amount of ruthenium consumed, the industrial sectors are in the following order:
- Electronic.
- Electrochemical.
- Chemical.
The catalytic properties of the element are in high demand. It is used in the synthesis of hydrocyanic and nitric acids, in the production of saturated hydrocarbons, glycerin and the polymerization of ethylene. In the metallurgical industry, ruthenium additives are used to increase anti-corrosion properties, to impart strength to alloys, chemical and mechanical resistance. Radioactive isotopes of ruthenium often help scientists in their research.
Many compounds of the element have also been used as good oxidizers 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 (the only metal of the platinum group). May provokedevelopment of allergic reactions, have a negative impact on the mucous membrane of the eyes and upper respiratory tract.
In medicine, the noble metal is used as a means of recognizing affected tissues. Medicines based on it are used to treat tuberculosis and various infections that affect human skin. For this reason, it looks very promising to use the ability of ruthenium to form stable nitroso complexes in the fight against diseases associated with excessive concentration of nitrates in the human body (hypertension, arthritis, septic shock and epilepsy).
Who is to blame?
Most recently, Western European scientists have seriously disturbed the public with a message that the content of the radioactive isotope of ruthenium Ru106 is growing over the continent. Experts completely exclude its self-education in the atmosphere. As well as an accidental release from a nuclear power plant, since then radionuclides of cesium and iodine would necessarily be present 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 irradiation of tissues and organs, the development of cancer. Possible sources of pollution, according to Western media, are located on the territory of Russia, Ukraine or Kazakhstan.
In response, a representative of the Department of Communications of Rosatom said that all enterprises of the state corporation worked and are working as usual. The International Atomic Energy Agency (IAEA), in its opinion, based on its own monitoring data,called all accusations against the Russian Federation groundless.
