Sodium molybdate

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Sodium molybdate
Sodium molybdate
Systematic name Sodium molybdate(VI)
Other names Disodium molybdate.
Molecular formula Na2MoO4
Molar mass Anhydrous 206 g/mol

Dihydrate 241.95 g/mol

Appearance White powder.
CAS number [7631-95-0]
Density and phase 3.78 g/cm3, solid
Solubility in water 65.5 g/100 g Water
Melting point 687°C
Boiling point ?°C
Basicity (pKb) N/A
MSDS External MSDS
EU classification Irritant (I)
R-phrases R36, R37, R38.
S-phrases None listed.
NFPA 704 N/A
Flash point Non-flammable.
Lethal doses (anhydrous)
3/4 hours inhalation-rat LC50 >2080 mg/m
ORAL-RAT LD50 4000 mg/kg
subcutaneous-mouse LD50 570 mg/kg
intravenous-cat LD50 917 mg/kg
intraperitoneal-mouse LD50 303 mg/kg
intraperitoneal-rat LD50 576 mg/kg
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions None listed.
Other cations None listed.
Related bases None listed.
Related compounds None listed.
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

Sodium molybdate, Na2MoO4, is useful as a source of molybdenum.

It is often found as the dihydrate, Na2MoO4 . 2H2O.

The structure of the Molybdate (IV) anion is tetrahedral. Two sodium cations coordinate with every one anion.[2]

File:Sodium molybdate structure.jpg


Sodium Molybdate was first synthesized by the method of hydration[1]; however, a more convenient synthesis is done by dissolving MoO3 in sodium hydroxide at 50-70 ºC and crystallizing the filtered product.[2] The anhydrous salt is prepared by heating to 100 ºC.

MoO3 + 2NaOH → Na2MoO4 ∙ 2H2O


Sodium molybdate is used in biochemistry and medicinal chemistry to track various organic chemicals that are colorless after a chromatographical procedure, which it always stains it blue. The blue color is also called molybdenum blue.

The agriculture industry uses 1 million pounds per year as a fertilizer. However, care must be taken because at a level of 0.3 ppm sodium molybdate can cause copper deficiencies in animals, particularly cattle.[2]

It is used for water treatment.

It is used in industry for corrosion inhibition, as it is a non-oxidizing anodic inhibitor.[2] The addition of sodium molybdate significantly reduces the nitrite requirement of fluids inhibited with nitrite-amine, and improves the corrosion protection of carboxylate salt fluids.[3]

According to an article from 1950 that was published in Nature, sodium molybdate is useful for curing a broccoli disease known as ‘whiptail’.


When reacted with sodium borohydride, molybdenum is reduced to a lower valent oxide:

Na2MoO4 + NaBH4 + 2H2O→ NaBO2 + MoO2+2NaOH+ 3 H2 [4]

Sodium molybdate reacts with the acids of dithiophosphates:

Na2MoO4 + (RO)2PS2H (R = Me, Et) → [MoO2(S2P(OR)2)2] which further reacts to form [MoO3(S2P(OR)2)4].[2]


Sodium Molybdate is incompatible with alkali metals, most common metals and oxidizing agents. It will explode on contact with molten magnesium. It will violently react with interhalogens (e.g., bromine pentafluoride; chlorine trifluoride). Its reaction with hot sodium, potassium or lithium is incandescent. (From the MSDS)


1. Spitsyn, Vikt. I.; Kuleshov, I. M. Zhurnal Obshchei Khimii 1951. 21. 1701-15.

2. Braithwaite, E.R.; Haber, J. Molybdenum: An outline of its Chemistry and Uses. 1994. Elsevier Science B.V. Amsterdam, The Netherlands.

3. Vukasovich, Mark S. Lubrication Engineering 1980. 36(12). 708-12.

4. Chi Fo Tsang and Arumugam Manthiram. Journal of Materials Chemistry 1997. 7(6). 1003–1006.

See also

External links