Molybdenum

CHEMICAL SUBSTANCE IDENTIFICATION

Chemical name                 

 Molybdenum

Synonyms                           

 Molybdenum metal

IUPAC name

 molybdenum

CAS No

 7439-98-7

REACH registration number

 pre-registered under REACH

EC No

Molecular formula              

 Mo

Substance group/chemical family

 mono-constituent /inorganic substance

Appearance

Physical state

Odour

Form

    Colour

 solid @  at 20°C and 1013 hPa [1]

 odourless [1]

 Powder (50%), Other (50%)

metallic, black to silvery

USES AND HANDLING ISSUES

Relevant identified uses

About 86% of molybdenum produced is used in metallurgy, with the rest used in chemical applications. The estimated global use is structural steel 35%, stainless steel 25%, chemicals 14%, tool & high-speed steels 9%, cast iron 6%, molybdenum elemental metal 6%, and superalloys 5%. Molybdenum powder is used as a fertilizer for some plants, such as cauliflower. Elemental molybdenum is used in NO, NO2, NOx analyzers in power plants for pollution controls. At 350 °C, the element acts as a catalyst for NO2/NOx to form NO molecules for detection by infrared light. Molybdenum anodes replace tungsten in certain low voltage X-ray sources for specialized uses such as mammography. The radioactive isotope molybdenum-99 is used to generate technetium-99m, used for medical imaging. The isotope is handled and stored as the molybdate [2].

Handling considerations

 Storage: Avoid formation of dust. Observe national and regional provisions in force. Store away from incompatible substances (Bromine Pentafluoride: violent reaction which may ignite, Chlorine Trifluoride: violent reaction that may ignite, Lithium: reacts, Magnesium: when heated a violent detonation may occur, Potassium: reacts with incandescence, Sodium: reacts violently). [1]

PHYSICO-CHEMICAL PROPERTIES

Molecular weight                                  

95.95 g/mol  [3]

Bulk density/Specific gravity

 10.18 g/cm3 @ 20°C [1]

pH

Particle size

EC

Melting point

 2 623 °C [1]

Boiling point

 4 639 °C @ 101 325 Pa [1]

Flash point

Flammability

non flammable [1]

Vapour density

Vapour pressure

Solubility in water

  5.5 - 12 mg/L @ 20 °C and pH 3.5 - 4.3  [1]

Solubility in organic solvents

Solubility in inorganic solvents

Hydrolysis

Ionicity in water

Surface tension

Dispersion properties

Specific surface

Stability and reactivity

Chemical stability

Reactivity hazards

Corrosivity

Polimerization

Incompatibility with various substances

 Bromine Pentafluoride: violent reaction which may ignite, Chlorine Trifluoride: violent reaction that may ignite, Lithium: reacts, Magnesium: when heated a violent detonation may occur, Potassium: reacts with incandescence, Sodium: reacts violently [1]

Special remarks on reactivity

Physical, chemical and biological coefficient

Koc

Kow

pKa

log Kp

water-sediment log Kd: 3.48 (3,020 L/kg) [1]

Henry-constant

ENVIRONMENTAL FATE AND BEHAVIOUR

Artificial pollution sources

General terrestrial fate

General aquatic fate

General atmospheric fate

General persistence and degradability

Abiotic degradation and metabolites

Biodegradation and metabolites

Bioconcentration

 molybdenum did not biomagnify in aquatic food chains [1]

Volatilization

Photolysis

Hydrolysis

Soil adsorption and mobility

ENVIRONMENTAL CONCENTRATIONS

Measured data

The regional (EU) ambient reasonable-worst-case concentration of dissolved molybdenum in european surface waters is 2.30 µg/L [1]

ECOTOXICOLOGICAL INFORMATION

General adverse effects on ecosystem

Acute toxicity (LC50, EC50)

Aquatic systems

 LC50 (4 days) 609.1 - 681.4 mg/L (fish) [1]

 LC50 (48 h) 1.006 - 2.729 g/L (aquatic inverterbrates) [1]

 EC50 (48 h) 130.9 - 2 847.5 mg/L (aquatic inverterbrates) [1

 EC50 (72 h) 218 - 2 453.6 mg/L (aquatic algae and cyanobacteria) [1]

 EC50 (7 days) 890.2 - 1 190 mg/L, (aquatic plants other than algae) [1]

EC50 (3 h) 820 mg/L, (microorganisms) [1]

EC50 (30 min) 1.1 g/L, (microorganisms) [1]

Terrestrial systems

Chronic toxicity (NOEC, LOEC)

Aquatic systems

 NOEC (84 days) 121 - 294.9 mg/L (fish) (Mo, as sodium molybdate) [1]

 NOEC (78 days) 48.9 - 152.7 mg/L (fish) [1]

 NOEC (37 days) 139 - 1 070 mg/L (fish) [1]

 NOEC (34 days) 27.7 - 203.5 mg/L (fish) [1]

 NOEC (28 days) 63 - 444.3 mg/L (fish) [1]

 NOEC (48 h) 1.653 g/L (aquatic inverterbrates) [1]

 NOEC (30 days) 79 mg/L, (aquatic inverterbrates) [1]

 NOEC (28 days) 116 mg/L, (aquatic inverterbrates) [1]

 NOEC (21 days) 49.9 - 377 mg/L, (aquatic inverterbrates) [1]

 NOEC (20 days) 26 mg/L, (aquatic inverterbrates) [1]

 NOEC (14 days) 393 - 1 564 mg/L, (aquatic inverterbrates) [1]

 NOEC (72 h) 27 - 938 mg/L (aquatic algae and cyanobacteria) [1]

 LOEC (72 h) 310 - 938 mg/L, (aquatic algae and cyanobacteria) [1]

 EC10 (72 h) 61.2 - 881 mg/L, (aquatic algae and cyanobacteria) [1]

 NOEC (7 days) 24.7 - 641 mg/L, (aquatic plants other than algae) [1]

 LOEC (7 days) 51.7 - 1 190 mg/L, (aquatic plants other than algae) [1]

 EC10 (7 days) 241.5 - 274 mg/L, (aquatic plants other than algae) [1]

 EC10 (3 h) 216.5 - 325 mg/L, (microorganisms) [1]

Terrestrial systems

 NOEC (56 days) 7.88 - 77.9 mg/kg soil dw, (terrestrial macroorganisms except arthropods) [1]

 EC10 (56 days) 8.21 - 6 307 mg/kg soil dw, (terrestrial macroorganisms except arthropods) [1]

 EC10 (28 days) 67.2 - 3 040 mg/kg soil dw, (terrestrial macroorganisms except arthropods) [1]

 EC10 (28 days) 37.9 - 7 285 mg/kg soil dw, (terrestrial arthropods) [1]

 EC10 (21 days) 0.4 - 3 476 mg/kg soil dw, (terrestrial plants) [1]

 EC10 (4 days) 3 - 869 mg/kg soil dw, (terrestrial plants) [1]

 EC10 (28 days) 35 - 10 000 mg/kg soil dw, (soil microorganisms) [1]

 EC10 (24 h) 1 - 10 000 mg/kg soil dw, (soil microorganisms) [1]

 NOEC (28 days) 400 mg/kg diet (birds) [1]

 LOEC (28 days) 500 mg/kg diet, (birds) [1]

HUMAN HEALTH EFFECTS and PROTECTION

Routes of human exposures

inhalation, oral

General effects

Endocrine disruption

Mutagenicity

Carcinogenicity

Reprotoxicity

Teratogenicity

Skin, eye and respiratory irritations

Metabolism:

absorption, distribution & excretion

Exposure limits

 (DNEL) 11.7 mg/m³ (repeated dose toxicity, inhalation, workers) [1]

 (DNEL) 3.33 mg/m³ (repeated dose toxicity, inhalation, general population) [1]

 (DNEL) 3.4 mg/kg bw/day (repeated dose toxicity, oral, general population) [1]

Drinking water MAC

Other information

Animal toxicity data

Acute toxicity (LD50)

 LD50 2 000 - 5 000 mg/kg bw (rat) (oral) [1]

 LC50 (4 h) 1.93 - 5.84 mg/L air (rat) (inhalation) [1]

 LD50 2 000 mg/kg bw (rat) (dermal) [1]

Chronic toxicity (NOEL, LOEL)

 NOAEL (rat): 17 - 60 mg/kg bw/day (oral) [1]

 NOAEC (rat): 100 mg/m³ air (inhalation) [1]

 NOAEC (mouse): 100 mg/m³ air (inhalation) [1]

 LOEC (mouse): 30 - 100 mg/m³ air (inhalation) [1]

ENVIRONMENTAL STANDARDS AND REGULATIONS

EINECS regulation

̵EINECS (European INventory of Existing Commercial chemical Substances) List

OSHA regulations etc.

OTHER INFORMATION, SPECIAL REMARKS

Classification and proposed labelling with regard to toxicological data

 No signal word

ECHA has no data from registration dossiers on the precautionary measures for using this substance. Additionally, the classification provided by companies to ECHA in CLP notifications identifies that this substance is a flammable solid, is suspected of damaging fertility or the unborn child and is a highly flammable liquid and vapour. [1]

CREATED, LAST UPDATE

Created

2018. 11. 06.

Last update

2018. 11. 07

REFERENCES

 [1] ECHA https://echa.europa.eu/registration-dossier/-/registered-dossier/15524/1, Accessed 06. November, 2018

 [2] Wikipedia, molybdenum: https://en.wikipedia.org/wiki/Molybdenum, Accessed 07. November, 2018

[3] Commission on Isotopic Abundances and Atomic Weights. http://www.ciaaw.org/molybdenum.htm, Accessed 07. November, 2018