Sodium molybdate
Overview
 
Sodium molybdate, Na2MoO4, is useful as a source of molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

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

The molybdate(VI) anion is tetrahedral. Two sodium cations coordinate with every one anion.
Sodium molybdate was first synthesized by the method of hydration. A more convenient synthesis is done by dissolving MoO3
Molybdenum(VI) oxide
Molybdenum trioxide is chemical compound with the formula MoO3. This compound is produced on the largest scale of any molybdenum compound. It occurs as the rare mineral molybdite...

 in sodium hydroxide at 50–70 °C and crystallizing the filtered product.
Encyclopedia
Sodium molybdate, Na2MoO4, is useful as a source of molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

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

The molybdate(VI) anion is tetrahedral. Two sodium cations coordinate with every one anion.

History

Sodium molybdate was first synthesized by the method of hydration. A more convenient synthesis is done by dissolving MoO3
Molybdenum(VI) oxide
Molybdenum trioxide is chemical compound with the formula MoO3. This compound is produced on the largest scale of any molybdenum compound. It occurs as the rare mineral molybdite...

 in sodium hydroxide at 50–70 °C and crystallizing the filtered product. The anhydrous salt is prepared by heating to 100 °C.
MoO3 + 2NaOH → Na2MoO4·2H2O

Uses

The agriculture industry uses 1 million pounds per year as a fertilizer. In particular, its use has been suggested for treatment of whiptail
Whiptail
Whiptail can refer to the following:* A common name for Blue grenadier, a species of fish of the genus Macruronus* A common name for lizards of the genus Cnemidophorus* Whiptail...

 in broccoli
Broccoli
Broccoli is a plant in the cabbage family, whose large flower head is used as a vegetable.-General:The word broccoli, from the Italian plural of , refers to "the flowering top of a cabbage"....

 and cauliflower
Cauliflower
Cauliflower is one of several vegetables in the species Brassica oleracea, in the family Brassicaceae. It is an annual plant that reproduces by seed...

 in molybdenum-deficient soils. However, care must be taken because at a level of 0.3 ppm sodium molybdate can cause copper deficiencies in animals, particularly cattle.

It is used in industry for corrosion inhibition, as it is a non-oxidizing anodic inhibitor. 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.

In industrial water treatment applications where galvanic corrosion is a potential due to bimetallic construction, the application of sodium molybdate is preferred over sodium nitrite. Sodium molybdate has the advantage in that the dosing of lower ppm's of molybdate allow for lower conductivity of the circulating water. Sodium molybdate at levels of 50-100 ppm offer the same levels of corrosion inhibition that sodium nitrite at levels of 800+ offer. By utilizing lower concentrations of sodium molybdate, conductivity is kept at a minimum and thus galvanic corrosion potentials are decreased.

Reactions

When reacted with sodium borohydride
Sodium borohydride
Sodium borohydride, also known as sodium tetrahydridoborate, is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are...

, molybdenum is reduced to a lower valent oxide:
Na2MoO4 + NaBH4 + 2H2O→ NaBO2 + MoO2 + 2NaOH+ 3 H2


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].

Safety

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
Bromine pentafluoride
Bromine pentafluoride, BrF5, is an interhalogen compound and a fluoride of bromine. It is a strong fluorination reagent.It melts at −61.30 °C and boils at 40.25 °C. BrF5 finds use in oxygen isotope analysis. Laser ablation of solid silicates in the presence of bromine pentafluoride releases O2 for...

; chlorine trifluoride
Chlorine trifluoride
Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colourless, poisonous, corrosive and very reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold...

). Its reaction with hot sodium, potassium or lithium is incandescent.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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