The most common oxidation states of platinum are +2 and +4. Platinum's +1 and +3 are less common, and metallic bonding in bimetallic (or polymetallic) compounds increases its stability.
Physical Properties
Pure platinum is a silvery-white metal with a luster and malleable properties. It has the highest malleability of any pure metal, outperforming gold, silver, and copper, but is less malleable than gold.
Platinum metal is extremely corrosion-resistant, very stable at high temperatures, and its electrical properties are also very stable. It does not oxidize at any temperature, but can be attacked by various halogens, cyanides, sulfur and caustics. Platinum is insoluble in hydrochloric and nitric acids, but will dissolve in hot aqua regia to form chloroplatinic acid (H2PtCl6).
All of these physical properties make platinum a widely used metal in industry. Because of its ability to resist erosion and retain luster, platinum is also used in jewelry.
Chemical Properties
The most common oxidation states of platinum are +2 and +4. Platinum's +1 and +3 are less common, and metallic bonding in bimetallic (or polymetallic) compounds can enhance its stability. Tetracoordinated platinum(II) compounds usually have a planar tetragonal structure formed by 16 electrons.
Monomer platinum metal has low reactivity, but it will dissolve in hot aqua regia to produce chloroplatinic acid (H2PtCl6): pt + 4 HNO3?+ 6 HCl → H2PtCl6?+ 4 NO2?+ 4 H2O
Platinum belongs to the group of soft acids, and so platinum has a chemical affinity with sulfur, e.g., with dimethylsulfoxide (DMSO); scientists have found various DMSO complexes.
Applications
Of the 218 tons of platinum sold in 2014, 98 tons were used in automotive emission control devices (45%), 74.7 tons in jewelry (34%), 20.0 tons in chemical production and petroleum refining (9.2%), and 5.85 tons in electrical applications such as the manufacture of hard disk drives (2.7%).
The remaining 28.9 tons were used in a variety of other minor applications, such as pharmaceutical and biomedical, glass manufacturing equipment, investments, electrodes, anti-cancer drugs, oxygen sensors, spark plugs and turbine engines.
1. Catalysts
The most common use of platinum is as a catalyst for chemical reactions, usually as platinum black. Platinum powder has been used as a catalyst since the early 19th century, when it was used to catalyze the ignition of hydrogen gas. Its most important application is as a catalytic converter in automobiles, where low concentrations of unburned hydrocarbons in exhaust gases are completely burned to carbon dioxide and water vapor.
In the petroleum industry, platinum is also used as a catalyst in a number of separate processes, particularly in the catalytic reforming of straight-run naphtha into high-octane gasoline rich in aromatic compounds.
2, precious metal investment
Platinum is a precious metal? commodity; its bullion has the ISO currency code XPT. coins, bars and ingots are traded or collected. Because of its inertness, platinum is used in jewelry, usually as a 90-95% alloy.
It is used for this purpose because of its prestige and inherent bullion value. Jewelry trade publications recommend that jewelers use tiny surface scratches (which they call "patina") as a desirable feature in an attempt to increase the value of platinum products.
References to Baidu Encyclopedia - Platinum
The above references? Baidu Encyclopedia - Platinum