Although the popular belief is that gold is the most expensive metal on the planet, at present it is not, since the most expensive metal in the world is rhodium, beating platinum and gold.

Over the last few years, the price of rhodium has only increased, due in large part to the decrease in supply by extractions in South Africa. Next to this African region, the other great extract of rhodium is Russia being in the background the region of Sudbury in Ontario or the Ural mountains.

chemical element, of Rh symbol, of atomic number 45 and atomic weight 102,905. Rhodium is a hard white metal, considerably less ductile than platinum or palladium, but much more ductile than any other metal in this group.

It is mainly used as an alloying element for platinum. It is an excellent catalyst for hydrogenation and is active in the catalytic reformation of hydrocarbons. Rhodium is also used in applications for electrical contacts. It is easily galvanized to form hard surfaces, resistant to wear and permanent shine, used both in stationary and sliding electrical contacts, in mirrors and reflectors, and as a finish in jewelry.

Rhodium is resistant to most common acids, including aqua regia, even at moderate temperatures. It is attacked by hot sulfuric acid, hot hydrobromic acid, sodium hypochlorite and free halogens at 200-600ºc (390-1110ºF).

Rhodium trichloride, RhCl3, is a red compound insoluble in water. Rhodium trihydroxide is soluble in some acids and can be used to produce rhodium salts. Rhodium sulfate, Rh2 (SO4) 3. XH2O, is red or yellow and soluble in water.

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Use of rhodium in INDUSTRY

One of its main uses is to increase the hardness of other elements such as platinum or palladium. To do this, rhodium alloys are made with platinum or palladium, which achieve a high resistance to corrosion and increase their hardness considerably as we have said. Among the uses of this type of alloy we can find rhodium in coils of furnaces, different elements of laboratories or in turbine reactors.

Use of rhodium in jewelry

As we discussed in one of our latest articles on white gold, rhodium is used in jewelry to give a very bright appearance and high resistance to corrosion to other materials. Specifically, gold and silver jewelry are applied a very thin layer of rhodium to give them that bright white color and give them a great hardness.

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Use of rhodium in automobiles

Rhodium is also used in a totally different sector from that of jewelery, and it is used in cars. Rhodium is used in the catalytic converters of cars, which are a part of the exhaust pipe that is used to reduce the emission of engine gases into the atmosphere. In the new hydrogen-powered cars, the use of rhodium is also necessary.

Effects of Rhodium on health

Rhodium compounds are found very rarely. All rhodium compounds should be considered highly toxic and carcinogenic. Rhodium compounds stain the skin tightly.

Flammable. Possible dust explosion if it is in powder or granular form, mixed with water. Reacts with oxygen difluoride causing fire hazard.

Routes of exposure: The substance can be absorbed by the body by inhalation of its aerosol.

Inhalation risk: Evaporation at 20 ° C is negligible; However, when dispersed, a dangerous concentration of airborne particles can be reached quickly.

The health effects of exposure to this substance have not been investigated. There is not enough data available on the effect of this substance on human health, therefore the utmost caution must be exercised.

As unique characteristics, its resistance to being dissolved by aqua regia, or strong water, stands out. That, by the way, of "water" has only the name, since it is formed by nitric acid and hydrochloride acid (2 solvents of renown) in the ratio of 3 to 1 (come on, that for every 3 liters of the first, 1 liter of the second is thrown). It is yellow, it is a smoker, and is capable of dividing 90% of the things that fall inside (ideal if you want to get rid of annoying evidence of a crime), including metals from the gold suit or the aforementioned platinum, of which only There is nothing capable of dissolving it. Well, the rhodium holds, unless it has been crushed to form fine rhodium powder. But, of course, in tutorial level, anyone can.

References for more information

https://en.wikipedia.org/wiki/Rhodium

https://www.moneymetals.com/rhodium-bar-1-oz/51