Molybdenum oxide (VI)

Molybdenum trioxide
Molybdenum trioxide
	; __ Mo 6+ __ O 2−
Are common
Systematic ; name	Molybdenum oxide (VI)
Traditional names	trioxomolybdenum, molybdite
Chem. formula	Moo 3
Physical properties
condition	yellow powder
Molar mass	143.94 g / mol
Density	(TV, at 20 ° C) 4.69
Hardness	1 - 2 [1]
Thermal properties
T. melt.	801 ° C
T. bale.	1155 ° C
Like heat resistant.	75.02 J / (mol · K)
Enthalpy of Education	−745.17 kJ / mol
Steam pressure	(734 ° C) 1 ; (797 ° C) 10; (954 ° C) 100 mmHg Art.
Chemical properties
Solubility in water	(18 ° C) 0.1066 g / 100 ml; (70 ° C) 2.055 g / 100 ml
Structure
Crystal structure	orthorhombic
Classification
Reg. CAS number	1313-27-5
PubChem
Reg. EINECS number
Smiles
Inchi
Chebi
ChemSpider
Security
LD 50	(rat, oral) 125 mg / kg

Molybdenum (VI) oxide (molybdenum trioxide, trioxomolybdenum, molybdite ) is a binary inorganic chemical compound of oxygen with molybdenum . Chemical formula ${\mathsf {MoO_{3}}}$ ${\ displaystyle {\ mathsf {MoO_ {3}}}}$ ${\ displaystyle {\ mathsf {MoO_ {3}}}}$ . This compound is produced on a large scale from any molybdenum compound. This compound is used as a raw material for the production of molybdenum metal.
The oxidation state of molybdenum in this compound is +6.

Content

Structure

Section of the chain of exchange of octahedrons along the edges. Oxygen atoms are shown in red

In the gas phase, three oxygen atoms are together bonded to the central molybdenum atom. Solid state anhydrous ${\mathsf {MoO_{3}}}$ ${\ displaystyle {\ mathsf {MoO_ {3}}}}$ consists of layers of distorted octahedrons ${\mathsf {MoO_{6}}}$ ${\ displaystyle {\ mathsf {MoO_ {6}}}}$ in the rhombic form of crystals. The edges of the octahedra form chains that are connected to oxygen atoms, which form the layers. The octahedra have one short O – Mo bond with unconnected oxygen ^[2] .

Properties and

Weakly paramagnetic birefringent white orthorhombic crystals of a layered structure, yellowing upon heating ^[3] . Reacts with acids, alkalis, a solution of ammonia and sodium sulfide ^[1] . It is soluble in water, in excess of alkali solutions or alkali metal carbonates. Molybdenum trioxide is produced by the industrial method of roasting molybdenum disulfide - the main ore of molybdenum:

{\mathsf {2MoS_{2}+7O_{2}\rightarrow 2MoO_{3}+4SO_{2}}}

{\ displaystyle {\ mathsf {2MoS_ {2} + 7O_ {2} \ rightarrow 2MoO_ {3} + 4SO_ {2}}}}

It is obtained by calcining molybdenum in air at high temperature:

{\mathsf {2Mo+3O_{2}{\xrightarrow {570^{\circ }C}}2MoO_{3}}}

{\ displaystyle {\ mathsf {2Mo + 3O_ {2} {\ xrightarrow {570 ^ {\ circ} C}} 2MoO_ {3}}}}

Laboratory synthesis involves acidification of an aqueous solution of sodium molybdate with perchloric acid ^[4] . This produces molybdenum diaqua trioxide and sodium perchlorate :

{\mathsf {Na_{2}MoO_{4}+2HClO_{4}+H_{2}O\rightarrow MoO_{3}(H_{2}O)_{2}+2NaClO_{4}}}

{\ displaystyle {\ mathsf {Na_ {2} MoO_ {4} + 2HClO_ {4} + H_ {2} O \ rightarrow MoO_ {3} (H_ {2} O) _ {2} + 2NaClO_ {4}}} }

Molybdenum triacode easily loses water, giving a monohydrate. Both are bright yellow substances. Molybdenum anhydride is dissolved in water, forming "molybdenum acid" (MoO ₃ · (2) H ₂ O).

Application

Molybdenum anhydride is used in the manufacture of metallic molybdenum, which serves as an additive to steel and corrosion-resistant alloys.

It entails the corresponding conversion from MoO ₃ in reaction with hydrogen at elevated temperatures:

{\mathsf {MoO_{3}+3H_{2}{\xrightarrow {t^{\circ }}}Mo+3H_{2}O}}

{\ displaystyle {\ mathsf {MoO_ {3} + 3H_ {2} {\ xrightarrow {t ^ {\ circ}}} Mo + 3H_ {2} O}}}

In addition, it is a co-catalyst for use in the industrial production of acrylonitrile by oxidation of propylene and ammonia .
Due to its layered structure and due to the property of a pair of ^{Mo ^VI} / _{Mo ^V} ions, this oxide is of interest for use in electrochemical devices and displays ^[5] .

Notes

↑ ¹ ² ³ ⁴ Molybdenum (VI) oxide (Rus.) 1. Date of treatment May 14, 2010. Archived on April 25, 2012.
↑ Wells, AF Structural Inorganic Chemistry. - Oxford: Clarendon Press, 1984. - ISBN 0-19-855370-6 .
↑ The most important compounds of molybdenum (Russian) . Date of treatment May 14, 2010. Archived July 7, 2011.
↑ Heynes, JBB; Cruywagen, JJ Yellow Molybdenum (VI) Oxide Dihydrate. - 1986. - S. 191. - (Inorganic Syntheses). - ISBN 0-471-83441-6 .
↑ Ferreira, FF; Souza Cruz, TG; Fantini, MCA; Tabacniks, MH; de Castro, SC; Morais, J .; de Siervo, A .; Landers, R .; Gorenstein, A. Solid State Ionics. - 2000 .-- S. 136-137, 357.

[химик.ру-1] ¹ ² ³ ⁴ Molybdenum (VI) oxide (Rus.) 1. Date of treatment May 14, 2010. Archived on April 25, 2012.

[2] Wells, AF Structural Inorganic Chemistry. - Oxford: Clarendon Press, 1984. - ISBN 0-19-855370-6 .

[3] The most important compounds of molybdenum (Russian) . Date of treatment May 14, 2010. Archived July 7, 2011.

[4] Heynes, JBB; Cruywagen, JJ Yellow Molybdenum (VI) Oxide Dihydrate. - 1986. - S. 191. - (Inorganic Syntheses). - ISBN 0-471-83441-6 .

[5] Ferreira, FF; Souza Cruz, TG; Fantini, MCA; Tabacniks, MH; de Castro, SC; Morais, J .; de Siervo, A .; Landers, R .; Gorenstein, A. Solid State Ionics. - 2000 .-- S. 136-137, 357.