Platinum is a mineral, natural Pt from the platinum group of the class of native elements, usually contains Pd, Ir, Fe, Ni. Pure platinum is very rare, most of the samples are represented by the ferrous variety (polyxene), and often by intermetallic compounds: isoferroplatinum (Pt, Fe) 3Fe and tetraferroplatinum (Pt, Fe) Fe. Platinum, represented by polyxene, is the most abundant platinum-group mineral in the earth's crust.
Polyxene color ranges from silver white to steel black. The line is metallic steel gray. Typical metallic luster. The reflectivity in polished thin sections is high - 65-70.
Hardness 4-4.5, in iridium-rich varieties - up to 6-7. Possesses malleability. The fracture is hooked. Cleavage is usually absent. Ud. weight-15-19. The relationship between the reduced specific gravity and the presence of voids occupied by natural gases, as well as inclusions of foreign minerals, was noted. Magnetic, paramagnetic. Conducts electricity well. Platinum is one of the most inert metals. It is insoluble in acids and alkalis, with the exception of aqua regia. Platinum also reacts directly with bromine, dissolving in it.
When heated, platinum becomes more reactive. It reacts with peroxides, and upon contact with atmospheric oxygen, with alkalis. Thin platinum wire burns in fluorine and produces a lot of heat. Reactions with other non-metals (chlorine, sulfur, phosphorus) are less active. When heated more strongly, platinum reacts with carbon and silicon, forming solid solutions, similar to the metals of the iron group.
RESERVES AND PRODUCTION
Platinum Platinum is one of the rarest metals: its average content in the earth's crust (clarke) is 5 × 10-7% by weight. Even the so-called native platinum is an alloy containing 75 to 92 percent platinum, up to 20 percent iron, as well as iridium, palladium, rhodium, osmium, less often copper and nickel.
Platinum compounds (mainly amminoplatinates) are used as cytostatics in the treatment of various forms of cancer. Cisplatin (cis-dichlorodiammineplatinum (II)) was the first to be introduced into clinical practice; however, more effective carboxylate complexes of diammineplatinum - carboplatin and oxaliplatin - are currently used.
Platinum and its alloys are widely used in jewelry making.
From the first quarter of the 19th century, it was used in World as an alloying additive for the production of high-strength steels.
Platinum is used as a catalyst (most often in an alloy with rhodium, as well as in the form of platinum black - a fine powder of platinum obtained by reducing its compounds).
Platinum is used to make vessels and stirrers used in the melting of optical glasses.
For the manufacture of chemically resistant and strong heating laboratory glassware (crucibles, spoons, etc.).
For the manufacture of permanent magnets with high coercive force and residual magnetization (alloy of three parts of platinum and one part of cobalt PlK-78).
Special mirrors for laser technology.
For the manufacture of durable and stable electrical contacts in the form of alloys with iridium, for example, contacts of electromagnetic relays (alloys PLI-10, PLI-20, PLI-30).
Distillation retorts for hydrofluoric acid production, perchloric acid production.
Electrodes for the production of perchlorates, perborates, percarbonates, peroxoduseric acid (in fact, the use of platinum determines the entire world production of hydrogen peroxide: electrolysis of sulfuric acid - peroxoduseric acid - hydrolysis - distillation of hydrogen peroxide).
Insoluble anodes in electroplating.
Heating elements of resistance furnaces.
Manufacturing of resistance thermometers.
Coatings for microwave technology elements (waveguides, attenuators, resonator elements).