Molecular Formula | Ir |
Molar Mass | 192.22 |
Density | 22.65 g/cm3 (lit.) |
Melting Point | 2450 °C (lit.) |
Boling Point | 4130 °C (lit.) |
Water Solubility | INSOLUBLE |
Solubility | Soluble in aqua regia. |
Appearance | wire |
Specific Gravity | 22.421 |
Color | White to pale yellow |
Exposure Limit | ACGIH: Ceiling 2 ppmOSHA: Ceiling 5 ppm(7 mg/m3)NIOSH: IDLH 50 ppm; Ceiling 5 ppm(7 mg/m3) |
Merck | 13,5102 |
Storage Condition | Flammables area |
Physical and Chemical Properties | Iridium is a silver-white metal (face-centered cubic crystal). Melting point 2410 °c. Boiling point 4130 °c. The relative density was 22.421. Soluble in aqua regia, insoluble in water, acid and alkali. |
Risk Codes | R36 - Irritating to the eyes R36/37/38 - Irritating to eyes, respiratory system and skin. R11 - Highly Flammable |
Safety Description | S16 - Keep away from sources of ignition. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. |
UN IDs | UN 3089 4.1/PG 2 |
WGK Germany | 3 |
TSCA | Yes |
HS Code | 28439000 |
Hazard Class | 4.1 |
Packing Group | III |
resistivity (resistivity) | 4.71 μΩ-cm |
NIST chemical information | Information provided by: webbook.nist.gov (external link) |
EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
introduction | iridium element symbol Ir, atomic number 77, atomic weight 192.22, peripheral electron arrangement 5 d76s2, located in group VIII of the sixth cycle. Atomic radius 135.7pm, first ionization energy 885kJ/mol, electronegativity 2.2, main oxidation numbers 3, 4, 6. Iridium is the chemical element with the second largest density found at present (second only to osmium). The density measured by X-ray crystal structure analysis experiment is 22.56g/cm3. In the environment of indoor temperature and standard atmospheric pressure, it is in the same way. The calculated density is 0.04g/cm3 higher than osmium. Iridium is the metal with the highest corrosion resistance, even at high temperatures of 2000 degrees Celsius, it retains corrosion resistance. |
Discovery history | In 1803, Smithson Trante discovered iridium in the insoluble impurities of natural platinum ore. Because the salt of this element has many bright colors, he named this new element "Iridium" according to the rainbow goddess Iris of Greek mythology ". |
Source | Iridium is one of the rarest elements in the earth's crust, with an average mass ratio of only 0.001 parts per million. The content of iridium in meteorites is much higher, generally more than 0.5 parts per million. Scientists believe that the content of iridium in the entire earth is much higher than that in the earth's crust, but because of its high density and irophilicity, it has sunk to the core of the earth when the earth is still in a molten state. Iridium appears in nature in the form of pure metals or alloys, especially iridium-osmium alloys in various proportions. Nickel and copper deposits contain platinum-based metal sulfides (such as (Pt,Pd)S), tellurides (such as PtBiTe), antimonides (PdSb) and arsenides (such as PtAs2). The platinum in these compounds will be replaced by a small amount of iridium and osmium. Like other platinum elements, iridium can form natural nickel alloys and copper alloys. |
Application | The earliest application of iridium was as a nib material, and later applied to injection needles, balance blades, compass brackets, electrical contacts, etc. Iridium crucible can be used to grow refractory oxide crystals. The crucible can work for thousands of hours at 2100~2200 ℃ and is an important precious metal vessel material. The high temperature oxidation resistance and thermoelectric properties of iridium make the iridium/iridium rhodium thermocouple the only precious metal temperature measuring material that can measure the high temperature of 2100 ℃ in the atmosphere. It can be used as a container material for radioactive heat source. Anodic iridium oxide film is a promising electrochromic material. Ir192 is a γ-ray source for nondestructive testing and radiochemotherapy. At the same time, iridium is a very important alloying element. Some iridium alloys are used in some key sectors; iridium compounds also have their own unique uses. |
Preparation | Iridium is a by-product of the nickel and copper mining and refining process. In the electrolytic refining process of nickel and copper, precious metals such as gold and silver, platinum elements, and non-metallic elements such as selenium and tellurium will accumulate on the positive electrode. This muddy substance must enter the solution to separate the metal from it. The specific method depends on the composition of the mixture, but there are mainly two kinds: sodium peroxide is added and dissolved in aqua regia, or directly dissolved in a mixed solution of chlorine and hydrochloric acid. |
Safety | The block of iridium metal has no biological use and is harmless because it does not react with biological tissues. Like most metals, fine metal powder of iridium is dangerous. Such powder irritates tissue and burns easily in the air. Since the treatment capacity of iridium compounds is generally very low, little is known about their toxicity. However, soluble salts of iridium, such as various iridium halides, are toxic. Most iridium compounds are insoluble, so they are difficult to be absorbed by the human body. Ir isotopes are as dangerous as other radioactive isotopes. The only related accident is accidental exposure to the isotope radiation during brachytherapy. The high-energy gamma rays emitted by Ir will increase the possibility of cancer. External exposure can cause burns, radiation poisoning and even death. Ingestion of Ir can lead to gastrointestinal intimal burns. Ir, Ir and Ir entering the body will mainly accumulate in the liver, and the gamma rays and beta radiation emitted will cause damage to the body. |
use | iridium's high melting point and high stability make it have important uses in many special occasions, but the brittleness and high temperature loss of iridium limit its application to a certain extent. The earliest application of iridium was as a nib material, and later the use of injection needles, balance blades, compass brackets, and electrical contacts was proposed. Iridium crucible can be used to grow refractory oxide crystals. The crucible can work for thousands of hours at 2100~2200 ℃ and is an important precious metal vessel material. The high temperature oxidation resistance and thermoelectric properties of iridium make the iridium/iridium rhodium thermocouple the only precious metal temperature measuring material that can measure the high temperature of 2100 ℃ in the atmosphere. It can be used as a container material for radioactive heat source. Anodic iridium oxide film is a promising electrochromic material. Ir192 is a γ-ray source for nondestructive testing and radiochemotherapy. At the same time, iridium is a very important alloying element. Some iridium alloys are used in some key sectors; iridium compounds also have their own unique uses. |
production method | industrial production can be made from ore by dry method; it can also be made from copper and nickel sulfide ore. By-products produced in the production process of copper and nickel can be used as raw materials and produced by wet smelting. The wet method uses the residual components after the extraction of nickel and copper as raw materials, adds aqua regia for extraction, extracts platinum and palladium, and then extracts rhodium, ruthenium, and osmium from the residue after treatment. Finally, the residue is added to the Wang water treatment, and the obtained solution is added to ammonium chloride for reaction to generate ammonium chloroiridium acid precipitation. After recrystallization, ammonium chloroiridium is reduced with hydrogen to produce about 99.9% iridium products. |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |