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Sergey Venezky
STORIES ON METALS

LITHIUM

THE LIGHTEST OF LIGHT

In his Prime. - Excursion in the past century. - The healing waters of carlsbad. - Which is easier? - Vaseline tubs. - Pilots wear vests. - Remedy for gout. - The need made. - Doesn't sink in water. - No not afraid of frost or heat. - In the interior of Antarctica. - Eternal grease. - Delicious whether glass? - Blue flame. - The first violin. - The results of the bombing. - Li fan neutrons. - Twenty Dneproges. - Good old kerosene. - Lithium vs lithium.... - Nuclear "glue". - Crystal from South Dakota. - Sesame! Rapturous!". - Suspicious roast.

In 1967, lithium, standing in the Periodic table D. I. Mendeleev was the first among metals, celebrated the 150th anniversary from the date of opening. Its anniversary item met in the Prime of life: the activities of its modern technology is interesting and multifaceted. However, experts believe that Li is not revealed yet fully their capabilities, and predict a great future. But let's take a journey into the past century will look in a quiet laboratory Swedish chemist Johan August Arfwedson. So: Sweden, 1817.

...Day after day, the scientist analyzes the mineral petalite found on mine With near Stockholm. Again and again he checks the results of the analysis, but each time the sum of all components is equal to 96%. Where lost 4%? What if...? Yes, no doubt: in the mineral contains some hitherto unknown element. Arfwedson conducting experience for experience, and then, finally, the goal has been achieved: open a new alkaline metal. And since, unlike their close relatives" - potassium and sodium, first discovered in organic products, the newcomer was found in the mineral, the scientist decides to call it lithium ("lites" in Greek - stone).

Soon Arfwedson finds the element and other minerals, and the famous Swedish chemist, Berzelius finds him in the mineral waters of carlsbad and Marienbad. By the way, and today, the most widely known are the sources of the resort of Vichy France, which thanks to the presence of lithium salts have a high balneological properties.

Lithium is a very lightIn 1818 Englishman Davy were able to distinguish the grains of pure lithium by electrolysis of its hydroxide, and in 1855 the German chemist Bunsen and independent of the English physicist Matessino by electrolysis of the molten chloride managed to get pure lithium. He was a soft silvery-white metal, almost twice lighter than water. In this regard, Li does not know the competitors among metals: aluminium harder it 5 times, iron - 15, lead 20, and osmium - 40 times!

Even at room temperature lithium reacts vigorously with nitrogen and oxygen. Try to leave a piece of lithium in glass vessel with a glass stopper. The metal will absorb all the air in the vessel will have a vacuum, and atmospheric pressure so tight "pripechatal" tube that you are unlikely to pull out. Therefore, store lithium is very difficult. If the sodium, for example, can easily be put in kerosene or gasoline, for lithium, this method is unacceptable - he immediately POPs up and lights up. To save a lithium rods, they are usually pushed into a tub of vaseline or paraffin, which envelop the metal and not allow him to show his reactionary tendencies.

More actively lithium combines with hydrogen. A small amount of metal may bind huge amounts of this gas: 1 kg of lithium hydride contains 2800 liters of hydrogen! During the second world war, tablets lithium hydride served American pilots portable source of hydrogen, which they enjoyed during accidents over the sea: under the action of water pills instantly decomposed, filling hydrogen rescue equipment - inflatable boats, life jackets, signal balls antenna.

Extremely high capacity of lithium compounds to absorb moisture resulted in their widespread use for cleaning the air in submarines, air respirators, air-conditioning systems.

The first attempts industrial use lithium refer to the beginning of our century. For almost a hundred years it was used chiefly in medicine as a remedy against gout.

During the first world war, Germany experienced an extreme need in the tin, very necessary industry. Since its tin raw materials, the country lacked, scientists had to find a replacement for this metal. Using lithium problem has been addressed: lead alloy with lithium ("ban-metal") proved to be an excellent anti-friction material. From this point, technique will not part with lithium alloys. Known alloys of lithium with aluminum, beryllium, copper, zinc, silver and other elements. Especially broad prospects alloys of lithium with another metal-light weight - magnesium with a good structural properties: because this alloy, if it is dominated by lithium lighter than water. But the trouble is that the alloys of similar composition unstable is easily oxidized in air. Metallurgists have long sought to create the composition and technology, which would provide lithiumania alloys durability. This problem could be solved by scientists of the Institute of metallurgy of the name A.A. Baikov Academy of Sciences of the USSR: in vacuum crucible furnace in an atmosphere of inert gas argon was obtained alloy of lithium with magnesium, not lucknawi in the air and not drowning in water.

Many of the valuable properties of lithium has high reactivity, low melting point (total of 180.5°C), low density chemical compounds make this item a welcome party of technological processes in ferrous and nonferrous metallurgy. He copes, for example, with the role of the degasser and deoxidizer - removes from molten metals dissolved therein gases, such as nitrogen, oxygen. Thanks to lithium structure of certain alloys becomes fine-grained and thereby improve their mechanical properties. In aluminium production, he successfully plays the role of catalyst. Additive compounds in the electrolyte increases the performance of the aluminum electrolysis cell; this reduces the required bath temperature, significantly reducing energy consumption.

First of electrolyte alkaline battery consisted only from solutions of caustic soda. With the introduction of a few grams of lithium hydroxide battery life increases threefold. In addition, significantly expands the temperature range of its validity: it is not discharged even when the temperature rises to 40°C and freezes at twenty below zero. Buslaeva the electrolyte these tests not under force. Unique miniature battery for electronic wristwatches created in Japan: the thickness of the battery in which the anode is a thin film of lithium (cathode made of titanium disulfide) a total of 34 microns, i.e. it is thinner than a human hair. Tiny electrical device withstands 2000 charge cycles, and each charge allows the clock to run 200-300 hours. A lot of hopes on lithium and designers of automotive firms in the U.S., for example, a lithium electric battery used for electric car that can accelerate to 100 kilometers per hour and go without charging hundreds of miles.

Some organic compounds of lithium (stearate, palmiet and others) retain their physical properties in a wide temperature range. This allows you to use them as a basis for lubricants used in military equipment. Lubricant, which includes lithium, helps Rovers working in Antarctica, to make raids into the depths of the continent, where frosts sometimes reach -80°C. Lithium grease is a reliable assistant motorists. This has convinced the owners of the "Lada", not accidentally calling her "eternal"once at the beginning of operation lubricate it some rubbing parts of the machine, and for many years they will not need this operation.

Who among us has not heard about the miracles worked by Indian yogis. In the eyes of the astonished audience they scrunch the glass into small pieces, like a plain biscuit, and swallow with an expression of such pleasure, though in my life tasted anything more delicious. And you don't have to use glass for food? "What a ridiculous question? Of course not!" - so, probably, you will think everyone who happen to read these lines, and make a mistake. It turns out that ordinary glass is soluble in water. Of course, not to the same extent as, say, the sugar, but still soluble. Accurate analytical balances show that together with a glass of hot tea we drink about one ten-thousandth of a gram of glass. But if the glass is melted to add to it a pinch of salts of lanthanum, zirconium, and lithium, its solubility in water decreases hundreds of times. It finds stability even with respect to sulfuric acid.

The activity of lithium in glass production is not limited by the reduced solubility of the glass. Lithium glass are characterized by valuable optical properties, good heat resistance, high resistivity, low dielectric loss. Lithium, in particular, is part of the glass, which produce a television picture tubes. If ordinary window glass handle in the molten salt of lithium, it forms a dense protective layer: glass becomes twice as stronger and more resistant to high temperatures. Small additions of this element significantly lower temperature melting glass.

Long a symbol of transparency was a drop of dew. But even transparent, like dew, glass no longer meet modern technology: it needs optical materials that are missed not only visible to the eye rays of light, but invisible, such as ultraviolet. Using conventional astrophysics telescopes cannot detect radiation of very distant galaxies. Of all known optics materials the high transparency to ultraviolet rays has a lithium fluoride. Lenses made of single crystals of this substance allows researchers to penetrate much deeper into the mysteries of the Universe.

The important role played by Li in the production of special glazes, enamels, paints, high quality porcelain and faience. In the textile industry one of the compounds of this element are used for bleaching and treating tissue, others for their color.

The fireworks are familiar lithium salts: they are painted in bright blue-green trail of tracer bullets and shells.

On pyrotechnic abilities lithium based next focus. Try to burn a lump of sugar with a match - you have nothing will come of it: sugar begins to melt, but will not light. If before this sugar RUB tobacco ashes, he easily breaks out a beautiful blue flame. The reason is that in tobacco, as in many other plants in relatively large quantities contains lithium. During the combustion of tobacco leaves part of its compounds remains in the ashes. They allow this simple chemical focus.

But, as we have said, is only a secondary, side lithium. He has a case and more serious. We are talking about nuclear energy, where Li, may soon begin to play the role of one of the first violins. Scientists have found that the nucleus of the isotope lithium-6 can be easily destroyed by neutrons. Absorbing a neutron, the nucleus of lithium becomes unstable and disintegrates, resulting in formation of two new atom: a light inert gas helium and rare superheavy hydrogen - tritium. At very high temperatures the atoms of tritium and other isotopes of hydrogen - deuterium combined. This process is accompanied by the release of enormous quantities of energy, usually referred to as fusion.

Especially vigorously fusion reactions take place when bombarded by neutrons connection isotope lithium-6 with deuterium - lithium deuteride targets. This substance serves as a nuclear fuel in lithium reactors, which have several advantages compared to uranium: Li considerably more accessible and cheaper than uranium, the reaction does not form radioactive fission products, regulated process easier.

Regarding high ability lithium-6 to capture slow neutrons formed the basis of its use as a regulator of the intensity of reactions in uranium reactors. Due to this property isotope has found application also in a protective screens against radiation, nuclear batteries with long life. It is possible that in a short time lithium-6 will work with the absorber of slow neutrons in a nuclear aircraft.

Like some of the other alkali metals, lithium is used as a coolant in nuclear installations. Here you can use it less scarce isotope lithium - 7 (natural lithium accounts for about 93%). This isotope, unlike its more easy "brother"may not serve as a raw material for the production of tritium and therefore is not of interest for fusion technology. But with the role of fluid he copes quite well. In this he is helped by the high heat capacity and thermal conductivity, large temperature range of the liquid state, a small viscosity, low density.

In recent times a serious right to lithium begins to present rocket technology. A lot of energy must be expended to overcome the force of gravity and escape into space. A rocket into orbit, the spacecraft-satellite, with the world's first cosmonaut Yuri Gagarin, had six engines with a total capacity of 20 million horsepower! It is the power of twenty such hydropower plants, as Dneproges.

Naturally, the choice of rocket fuel is an issue of exceptional importance. While the most efficient fuel is kerosene (Yes, good old kerosene!), oxidizable liquid oxygen. The combustion of this fuel is allocated one and a half times more energy than in the explosion of nitroglycerine strongest explosives.

Excellent prospects can have the use of metal fuel. The theory and methods of using metals as fuel for rocket engines first developed more than half a century ago, the great Soviet scientists F.A. Tsander and Y. Kondratyuk. One of the most suitable for this purpose metal is lithium (higher calorific value can boast of a beryllium). Published in the United States patents for solid rocket propellant containing 51-68% of metallic lithium.

Interestingly, in the process of rocket engines lithium opposes... lithium. As a component of fuel, it allows you to develop a colossal temperature, and has high heat resistance and europornstar lithium ceramic materials (for example, stopala)used as coating nozzles and combustion chambers, protect them from the ravages of lithium-fuel.

In these days technology has a wide variety of synthetic materials - polymers, successfully replacing steel, brass, glass. But engineers often encounter great difficulties when in the manufacture of some products they need to combine polymers with each other or with other materials. Thus, the fluorine-containing polymer PTFE, excellent anti - corrosion coating - for a long time did not find practical application due to the fact that poorly glued to the metal. Soviet scientists developed the original technology of nuclear welding of polymers with different materials. On welded surfaces apply a small amount of lithium compounds or boron, which serve as a kind of "nuclear glue". The irradiation of these layers of neutron-nuclear reactions occur, accompanied by a significant release of energy, making for a very short time (less than ten-billionth of a second) in the materials appear microparts with temperatures in the hundreds and even thousands of degrees. But for those moments molecules boundary layers have time to mix and sometimes form between a new chemical bond - the nuclear welding.

Typically, the elements located in the upper left corner of the table DI periodic, widespread in nature. But, unlike most of its neighbors - sodium, potassium, magnesium, calcium, aluminum, which is rich our planet, lithium is relatively rare. There are about thirty minerals containing this valuable element. The main natural compound lithium - spodumene. Crystals of this mineral, reminiscent of railway sleepers or trunks of trees sometimes grow to giant size in South Dakota (USA) found a crystal length of more than 15 meters; mass was measured in tens of tons. In American fields discovered a very beautiful emerald-green and pink-purple varieties of spodumene - semi-precious minerals spodumene and kunzite.

Great value as raw material for the production of lithium can be granitic pegmatites. It is estimated that one cubic kilometer of granite signed more than one hundred thousand tons of lithium is many times greater than is produced annually worldwide. Side by side with lithium in granite pantries are stored niobium, tantalum, zirconium, thorium, uranium, neodymium, cesium, cerium, praseodymium, and many other rare items. But how to get granite to share with a person of their wealth? Scientists are looking for and, of course, they will be able to create methods that, like the magic words "sesame! Be opened,", will allow people to reveal the granite storehouses.

Ending a story about lithium, are going to tell you about a funny story in which this element has played a very important role. In 1891, a graduate of Harvard University, Robert wood (afterwards the famous American physicist) arrived in Baltimore to study chemistry at the local University. Staying in a student house, wood soon heard that the mistress allegedly often prepares the morning roast... remnants of yesterday's lunch, collected from the plates. But how to prove it?

Big fan of finding for any task original and yet easy solution, the wood has not changed him this time. One day, when lunch was served steak, he left on the plate a few large pieces of meat, sprinkled them with lithium chloride is completely harmless substance, similar in appearance and taste to ordinary table salt. The next day, the slices of roast meat, served to students at Breakfast, were consigned to burning" in front of the slit of the spectroscope. The red line of the spectrum inherent to lithium, put the dot on the i: extremely economical mistress of the house was exposed. And the wood many years later with pleasure recalled his investigative experiment.

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