Chemical Properties
Sodium molybdate is the sodium salt of molybdic acid. It forms white, rhombic crystals that are sparingly soluble in water and insoluble in acetone. Crystallization from an alkaline aqueous solution (pH above 8) yields the dihydrate, which appears as white rhombohedral crystals with a relative density of 3.28. In this structure, the molybdate anion (MoO₄²⁻) exhibits a regular tetrahedral coordination. Upon heating to 100°C, the dihydrate loses two water molecules to form the anhydrous compound. The anhydrous form is readily soluble in water but insoluble in ethyl acetate.
Gradually acidifying a sodium molybdate solution to lower its pH induces the polymerization of molybdate ions, forming various polymolybdates such as sodium dimolybdate, trimolybdate, tetramolybdate, octamolybdate, and decamolybdate.
Although molybdenum can form compounds in oxidation states from zero to +6, only the hexavalent molybdate compounds are stable. The primary ore for producing molybdate raw materials is molybdenite (MoS₂).
Uses
Sodium Molybdate is used in method for preparing fermentation medium with reduced color and viscosity.
Uses
Sodium molybdate (Na
2MO
4) may be used as an electrolyte additive, for use in electrochemical capacitors. Addition of Na
2MO
4 as an electrolyte additive may result in enhanced capacitance, corrosion prevention and stabilized performance.
It may also be used as a catalyst during the manufacture of paints and dyes.
Uses
Reagent in analytical chemistry, paint pigment,
production of molybdated toners and lakes, metal
finishing, brightening agent for zinc plating, corro-
sion inhibitor, catalyst in dye and pigment produc-
tion, additive for fertilizers and feeds, micronutri-
ent.
Preparation
Sodium molybdate dihydrate, which is obtained by evaporating an aqueous solution of molybdenum trioxide and sodium hydroxide, can be converted to the anhydrous form by heating at 100 °C.
Definition
ChEBI: Sodium molybdate (anhydrous) is an inorganic sodium salt having molybdate as the counterion. It has a role as a poison and a NMR chemical shift reference compound. It contains a molybdate.
General Description
Sodium molybdate has corrosion resistant properties. On heating, it undergoes degradation and releases Na
2O fumes.
Flammability and Explosibility
Non flammable
reaction suitability
reagent type: catalyst
core: molybdenum
Agricultural Uses
Sodium molybdate (NazMoO4-2H2O), which is an
important molybdenum source, is applied along with
other fertilizers or as a foliar spray (with 39%
molybdenum). Sodium molybdate is the sodium salt of
molybdic acid. Fusing molybdenum oxide with sodium
carbonate or hydroxide makes sodium molybdate.
Molybdenum is an essential component of the enzyme
nitrate reductase which catalyzes the conversion of
nitrate (NO
3-) to nitrite (NO
2-). It is also a component of
the nitrogenase enzyme involved in nitrogen fixation by
root nodule bacteria of leguminous crops. Soaking seeds
in sodium molybdate solution (made with slurry or dust)
before sowing is an effective seed treatment. Sodium
molybdate, the most commonly used fertilizer supplying
molybdenum, is used as foliar spray, or in mixed
fertilizers. It is also used in seed treatment.
Biological Activity
sodium molybdate is an acid phosphatase inhibitor. the osteoclastic acid phosphatase isoenzyme, secreted by osteoclasts, is a member of a widely-distributed class of iron-containing proteins with acid phosphatase activity. elevated plasma isoenzyme levels are associated with increased bone turnover in metabolic disease. by inhibiting this class of acid phosphatases, sodium molybdate is capable of abolishing bone resorption. in addition, sodium molybdate has been shown to stabilize the nonactivated glucocorticoid-receptor complex.1. zaidi m, moonga b, moss dw, et al. inhibition of osteoclastic acid phosphatase abolishes bone resorption. biochemical and biophysical research communications, 1989, 159(1): 68-71.2. denis m, wikström ac, gustafsson ja. the molybdate-stabilized nonactivated glucocorticoid receptor contains a dimer of mr 90,000 non-hormone-binding protein. journal of biological chemistry, 1987, 262(24): 11803-11806.
Safety Profile
Poison by
intraperitoneal route. Moderately toxic by
subcutaneous and intravenous routes.
Experimental reproductive effects. Mutation
data reported. When heated to
decomposition it emits toxic fumes of
Na2O. See also MOLYBDENUM
COMPOUNDS.
Toxics Screening Level
The screening level for the elemental molybdenum and insoluble molybdenum compounds is 30 μg/m3, while the screening level for soluble molybdenum compounds is 5 μg/m3 based on an 8 hour averaging time.
