HuagongsheHuagongshe Chemistry Print Report · For research reference only
Rhodium
Rh · RHODIUM ON ALUMINA · RHODIUM ON CARBON · Rhodium powder · 5% Rhodium on carbon · Rh-103 · rhodium atom · RHODIUM BLACK
Identifiers & Physical Properties
| CAS No. | 7440-16-6 |
|---|---|
| Molecular formula | Rh |
| Average molar mass | 102.9055 g/mol |
| Monoisotopic mass | 102.90549 g/mol |
| SMILES | [Rh] |
| InChIKey | MHOVAHRLVXNVSD-UHFFFAOYSA-N |
| PubChem CID | 23948 |
| ChEBI | CHEBI:33359 |
| EC No. | 231-125-0 |
Chemical & Physical Properties
| Topological polar surface area | 0 |
|---|---|
| Hydrogen bond donors | 0 |
| Hydrogen bond acceptors | 0 |
| Rotatable bonds | 0 |
| Heavy atoms | 1 |
| Formal charge | 0 |
| Complexity | 0 |
| Density | 12.41 (metal) (NIOSH, 2024) - Denser than waterwill sink12.41 g/cu cm @ 20 °C12.4 g/cm³12.41 @25 °C12.41 g/cm3 (lit.) |
| Color/Form | Silvery-white, soft, ductile, malleable metalface-centered cubic structure...In air, it occurs in the form of gray fume or dust. |
| Solubility | Insoluble (NIOSH, 2024)Insoluble in acids and aqua regiasoluble in fused potassium bisulfate.Insoluble in hot or cold watersoluble in concentrations of sulfuric acid and in sulfuric acid + hydrochloric acid.Solubility in water: noneinsoluble in acid solutions, slightly soluble in aqua regia |
| Boiling point | 6741 °F at 760 mmHg (NIOSH, 2024)3695 °C3727 °C @760 [mm Hg]3727 °C (lit.) |
| Melting point | 3571 °F (NIOSH, 2024)1964 °C1965 °C1966 °C1966 °C (lit.) |
| Vapor pressure | 0 mmHg (approx) (NIOSH, 2024)1 Pa @ 2015 °C10 Pa @ 2223 °C100 Pa @ 2476 °C1 kPa @ 2790 °C10 kPa @ 3132 °C100 kPa @ 3724 °Cdepends upon the specific compound |
| Physical Description | Rhodium metal fume is a reddish-gray to black dust-like powder. mp: 1966 °C, bp: 3727 °C. Insoluble in water. Bulk rhodium is a white or blueish-white, hard, ductile, malleable metal. The appearance and other properties of insoluble Rh compounds varies depending upon the specific compound.Dry PowderOther SolidMetal: White, hard, ductile, malleable solid with a bluish-gray luster[NIOSH]GREY-TO-BLACK POWDER.White, hard, ductile, malleable solid with a bluish-gray luster. Metal fume is a reddish-gray to black dust-like powder.Appearance and odor vary depending upon the specific soluble rhodium compound. |
| Stability/Shelf Life | Absorbs oxygen when meltedat a red heat is slowly oxidized to the sesquioxide.Converted to trihalide by chlorine or bromine at a red heatnot attacked by fluorine. |
| Other Experimental Properties | Atomic number 45valences 1-6most common states 1, 3One naturally occurring isotope:103artificial radioactive isotopes: 97-102104-110Electrical resistivity 4.51 microohm-cm @ 0 °CBrinell hardness: 100Not attacked by acids even aqua regia when in compact formthe finely divided metal reacts with aqua regiaAbsorbs oxygen when meltedat a read heat is slowly oxidized to the sesquioxideConverted to the trihalide by chlorine or bromine at a red heatnot attacked by fluorine.Enthalpy of formation: 556.9 kJ/mol (gas)Heat capacity: 25.0 J/mol K (crystal)21.0 J/mol K (gas)Enthalpy of fusion: 26.59 kJ/molFor more Other Experimental Properties (Complete) data for RHODIUM (9 total), please visit the HSDB record page. |
| Storage conditions | Inert atmosphere,Room Temperature |
| Physical state | wire |
| Color | Red |
| Specific gravity | 12.41 |
| pH | 0.5 (20°C in H2O) |
| Resistivity | 4.33 μΩ-cm, 20°C |
| Electrical Conductivity | 2.3× 107S/m |
| Thermal conductivity | 150 W/(m·K) |
| Specific heat capacity | Cp(crystal): 0.24 J/(g·K)Cp(gas): 0.2 J/(g·K), at 25℃ |
| Merck | 14,8186 |
| Exposure limits | ACGIH:TLV-TWA 1.0 mg/m3 —Metal 1.0 mg/m3,as Rh — Insoluble compounds 0.01 mg/m3,as Rh — Soluble compoundsOSHA:PEL-TWA 0.1 mg/m3NIOSH:REL-TWA 0.1 mg/m3 |
| InChI | 1S/Rh |
| InChIKey | MHOVAHRLVXNVSD-UHFFFAOYSA-N |
| SMILES | [Rh] |
| Hardness, Brinell | 722, Converted from Vickers for 3000 kg load/10 mm ball Brinell test. |
| Hardness, Rockwell A | 83, Converted from Vickers. |
| Hardness, Rockwell C | 63, Converted from Vickers. |
| Hardness, Vickers | 800 |
| Modulus of Elasticity | 359 GPa |
| Hardness, Rockwell B | 51, Converted from Vickers. |
| CAS DataBase Reference | 7440-16-6(CAS DataBase Reference) |
| EWG's Food Scores | 2 |
| FDA UNII | DMK383DSAC |
| NIST Chemistry Reference | Rhodium(7440-16-6) |
| EPA Substance Registry System | Rhodium (7440-16-6) |
| UNSPSC Code | 41116107 |
| NACRES | NA.24 |
| GHS pictogram | GHS07,GHS08,GHS02 |
| Signal word | Danger |
| GHS hazard statements | H315-H319-H228-H413-H332-H335-H373 |
| GHS precautionary statements | P210-P240-P241-P280-P370+P378a-P261-P305+P351+P338-P405-P501a-P260-P314-P304+P340-P312a-P403+P233 |
| Hazard symbols | C,Xi,F |
| Risk statements (R) | 36/38-11-36/37/38-36-34-23 |
| Safety statements (S) | 26-24/25-16-22-36-17-45-36/37/39 |
| UN transport number | UN 3089 4.1/PG 2 |
| Occupational exposure band (OEB) | D |
| Occupational exposure limit (OEL) | TWA: 0.1 mg/m3 |
| Water hazard class (WGK) | 3 |
| RTECS number | VI9069000 |
| TSCA inventory status | TSCA listed |
| Hazard class | 4.1 |
| Packing group | III |
| Customs code | 7110390000 |
| Storage class | 13 - Non Combustible Solids |
| Hazardous substances data | 7440-16-6(Hazardous Substances Data) |
| Immediately dangerous to life or health concentration | 100 mg Rh/m3 |
| REACH registrations | Active |
| Limited quantities | 1.0 Kg (2.2 lbs) |
| Excepted quantities | Max Inner Pack (30g or 30ml) and Max Outer Pack (500g or 500ml) |
Safety & Regulations
| GHS classification | This chemical does not meet GHS hazard criteria for 81.3% (239 of 294) of all reports.DangerH228 (15.3%): Flammable solid [Danger Flammable solids]P210, P240, P241, P280, and P370+P378 (click each P-code to see the statement)Aggregated GHS information provided per 294 reports by companies from 11 notifications to the ECHA C&L Inventory.Reported as not meeting GHS hazard criteria per 239 of 294 reports by companies.There are 9 notifications provided by 55 of 294 reports by companies with hazard statement code(s).Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. |
|---|---|
| Regulatory information | Chemical: RhodiumRhodium is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Rhodium are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)Status: Active Update: 21-06-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/21075Rhodium: Does not have an individual approval but may be used under an appropriate group standard |
| Other safety information | IMAP assessments - Rhodium: Environment tier I assessmentIMAP assessments - Rhodium: Human health tier I assessment |
| DOT label | Flammable Solid |
| Fire hazards | Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:May react violently or explosively on contact with water. Some are transported in flammable liquids. May be ignited by friction, heat, sparks or flames. Some of these materials will burn with intense heat. Dusts or fumes may form explosive mixtures in air. Containers may explode when heated. May re-ignite after fire is extinguished. (ERG, 2024)Many reactions may cause fire or explosion. |
| Fire potential | Moderate when exposed to heat or flame.Flammable in powder form. |
| Health hazards | Excerpt from NIOSH Pocket Guide for Rhodium (metal fume and insoluble compounds, as Rh):Exposure Routes: InhalationSymptoms: Possible respiratory sensitizationTarget Organs: Respiratory system (NIOSH, 2024) |
| Hazards summary | Can cause occupational contact urticaria[Kanerva, p. 219] The metals in this group [platinum, palladium, iridium, osmium, rhodium, and ruthenium] generally are nontoxic in the metallic state, but the soluble halide salts (particularly of Pt) and osmium tetroxide are highly reactive. Exposure to these elements results in hypersensitivity allergic reactions in susceptible individuals. [Sullivan, p. 911] Tram drivers in Rome were exposed to Pt, Rh and Pd from catalytic converters at levels about 10 times lower than those known to cause adverse effects in workers. [PMID 18849761] Occupational asthma in a electroplating worker confirmed by bronchoprovocation testing[Malo] |
| Reactive group | Metals, Less Reactive |
| Reactivity Alerts | Highly FlammableStrong Reducing AgentKnown Catalytic Activity |
| OSHA Standards | Permissible Exposure Limit: Table Z-1 8-Hour Time Weighted Avg: 0.1 mg/cu m. /Rhodium (as Rh), metal fume and insoluble compounds/ |
| Reactivity Profile | RHODIUM (METAL FUME) is flammable. Acts as a reducing agent. Reacts violently with BrF5, ClF3 and OF2. Reacts with fluorine, with chlorine (when heated), hydrogen peroxide, sulfur dioxide (when heated), and nitrogen dioxide. Also incompatible with Zn. May catalyze reactions between other materials.Reactivity may be altered by the presence of insoluble rhodium compounds depending on the specific compounds and their proportions in the mixture. |
| Chemical Dangers | Reacts violently with halogens. This generates fire hazard. Rhodium is a catalytic substance and may cause reaction in contact with many organic and inorganic substances, causing fire and explosion hazard. |
| Fire fighting | Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:DO NOT USE WATER, FOAM OR CO2. Dousing metallic fires with water will generate hydrogen gas, an extremely dangerous explosion hazard, particularly if fire is in a confined environment (i.e., building, cargo hold, etc.). Use DRY sand, graphite powder, dry sodium chloride-based extinguishers, or class D extinguishers. Confining and smothering metal fires is preferable rather than applying water. If it can be done safely, move undamaged containers away from the area around the fire.FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: If impossible to extinguish, protect surroundings and allow fire to burn itself out. (ERG, 2024)In case of fire in the surroundings, use appropriate extinguishing media. |
| First aid measures | Fresh air, rest.Rinse and then wash skin with water and soap.First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.Rinse mouth. |
| First aid | Excerpt from NIOSH Pocket Guide for Rhodium (metal fume and insoluble compounds, as Rh):Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.Swallow: MEDICAL ATTENTION IMMEDIATELY - If this chemical has been swallowed, get medical attention immediately. (NIOSH, 2024)(General first aid procedures)Breathing: Respiratory supportSwallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately. |
| Safe storage | See Chemical Dangers. |
| Nonfire spill response | Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. (ERG, 2024) |
| Disposal methods | SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices. |
| Spillage disposal | Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Sweep spilled substance into covered containers. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations. |
| Isolation and Evacuation | Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.LARGE SPILL: Consider initial downwind evacuation for at least 50 meters (160 feet).FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directionsalso, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024) |
| Eye Prevention | Wear safety goggles. |
| Inhalation Risk | A harmful concentration of airborne particles can be reached quickly when dispersed. |
| Skin Prevention | Protective gloves. |
| Exposure Prevention | PREVENT DISPERSION OF DUST! |
| Target organs | respiratory system |
| Adverse effects | Asthma - Reversible bronchoconstriction (narrowing of bronchioles) initiated by the inhalation of irritating or allergenic agents.ACGIH Carcinogen - Not Classifiable. |
| Exposure routes | inhalation |
| Signs and Symptoms | Cough.Redness.Possible resp sensitization |
| Natural Pollution Sources | Belongs to the platinum group of metals. One of rarest elementsconstitutes about 1x10-7% of the crust of the earthfound in small quantities associated with all native platinum: in minerals rhodite, sperrylite and iridosmine... Discovered in 1803 by Wollaston......Obtained from South America. ...In river sands of the Urals and in North America and South America. ...With other platinum metals in copper-nickel sulfide ores of the Sudbury, Ontario, region. |
| Human Toxicity Excerpts | /HUMAN EXPOSURE STUDIES/ No toxic effects of rhodium have been reported from...observations of human beings./HUMAN EXPOSURE STUDIES/ Workers wearing rings coated with rhodium showed negative rhodium patch tests though all other metals of which rings were constituted gave positive results./HUMAN EXPOSURE STUDIES/ Potential symptom of overexposure to metal fumes and insoluble compounds is respiratory sensitization. |
| Evidence for Carcinogenicity | A4Not classifiable as a human carcinogen. /Rhodium metal & insol and sol cmpd, as Rh/ |
| Antidote and Emergency Treatment | Basic treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with normal saline during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poison A and B/Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in respiratory arrest. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. Watch for signs of fluid overload. Consider drug therapy for pulmonary edema ... . For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poison A and B/ |
| Occupational exposure band (OEB) | D |
| Occupational exposure limit (OEL) | TWA: 0.1 mg/m3 |
| Water hazard class (WGK) | 3 |
| Immediately dangerous to life or health concentration | 100 mg Rh/m3 |
| TSCA inventory status | TSCA listed |
| RTECS number | VI9069000 |
| UN transport number | UN 3089 4.1/PG 2 |
| Customs code | 7110390000 |
| Risk statements (R) | 36/38-11-36/37/38-36-34-23 |
| Signal word | Danger |
| GHS pictogram | GHS07,GHS08,GHS02 |
| Hazard symbols | C,Xi,F |
| Safety statements (S) | 26-24/25-16-22-36-17-45-36/37/39 |
| Hazard class | 4.1 |
| Storage class | 13 - Non Combustible Solids |
| Packing group | III |
| GHS hazard statements | H315-H319-H228-H413-H332-H335-H373 |
| Limited quantities | 1.0 Kg (2.2 lbs) |
| Excepted quantities | Max Inner Pack (30g or 30ml) and Max Outer Pack (500g or 500ml) |
| REACH registrations | Active |
| GHS precautionary statements | P210-P240-P241-P280-P370+P378a-P261-P305+P351+P338-P405-P501a-P260-P314-P304+P340-P312a-P403+P233 |
| Hazardous substances data | 7440-16-6(Hazardous Substances Data) |
Applications & Uses
Description
Rhodium is one of the platinum group elements, and is found at very low concentrations in the Earths crust. Rhodium was discovered by William Hyde Wollaston (England) in 1804. The origin of the name comes from the Greek word rhodon, meaning rose. The plated solid is very corrosion resistant and exceptionally hard. While inert in air and acids, it can produce a violent reaction to chlorine, bromine pentafluoride, bromine trifluoride, and fluorine monoxide.
Occurrence
Rhodium is rare, but not as rare as ruthenium. It makes up only 1 part in 20 million of theelements found in the Earth’s crust. Even so, it is considered the 79th most abundant elementand is found mixed with platinum ore, and to a lesser extent, it is found with copper andnickel ores. It is found in Siberia, South Africa, and Ontario, Canada.Rhodium is recovered from platinum and other ores by refining and purification processesthat start by dissolving the other platinum group metals and related impurities with strongacids that do not affect the rhodium itself. Any remaining platinum group elements areremoved by oxidation and bathing the mixture in chlorine and ammonia.Rhodium is usually produced as a powder and can be formed by either casting or powdermetallurgy.
History
Wollaston discovered rhodium in 1803-4 in crude platinum ore he presumably obtained from South America. Rhodium occurs native with other platinum metals in river sands of the Urals and in North and South America. It is also found with other platinum metals in the copper-nickel sulfide ores of the Sudbury, Ontario region. Although the quantity occurring here is very small, the large tonnages of nickel processed make the recovery commercially feasible. The annual world production of rhodium in 1999 was only about 9000 kg. The metal is silvery white and at red heat slowly changes in air to the sesquioxide. At higher temperatures it converts back to the element. Rhodium has a higher melting point and lower density than platinum. Its major use is as an alloying agent to harden platinum and palladium. Such alloys are used for furnace windings, thermocouple elements, bushings for glass fiber production, electrodes for aircraft spark plugs, and laboratory crucibles. It is useful as an electrical contact material as it has a low electrical resistance, a low and stable contact resistance, and is highly resistant to corrosion. Plated rhodium, produced by electroplating or evaporation, is exceptionally hard and is used for optical instruments. It has a high reflectance and is hard and durable. Rhodium is also used for jewelry, for decoration, and as a catalyst. Fifty-two and isomers are now known. Rhodium metal (powder) costs about $180/g (99.9%).isotopes
Uses
As an alloy with platinum; as a corrosion-resistant electroplate for protecting silverware from tarnishing; for making high-reflectivity mirrors for cinema projectors, searchlights. Spongy or black rhodium is used as a catalyst in various organic hydrogenation and oxidation reactions.
Uses
Rhodium is commercially used as an alloy metal with other metals to form durable hightemperatureelectrical equipment, thermocouples, electrical contacts and switches, and laboratorycrucibles.Because of its high reflectivity, it is used to electroplate jewelry, silverware, optical instruments,mirrors, and reflectors in lighting devices.When rhodium is combined with platinum and palladium, the elements together form theinternal metals of automobile catalytic converters, which convert hot unburned hydrocarbonexhaust gases to less harmful CO2 and H2O. Similar alloys are used to manufacture hightemperatureproducts such as electric coils for metal refining furnaces and high-temperaturespark plugs.
Uses
Rhodium is a transition metal catalyst used in a multitude of inorganic synthesis.
General Description
This product has been enhanced for energy efficiency.