Community GroupsMembersToolsPinns 3D CAD Catalogs PDF Catalogs 3D Share Contacns Support FAQsManuals ENManuals DE Search
Sodium chromate is the inorganic compound with the formula Na2CrO4. It exists as a yellow hygroscopic solid, which can form tetra-, hexa-, and decahydrates. It is an intermediate in the extraction of chromium from its ores. Sodium chromate, like other hexavalent chromium compounds, is toxic and carcinogenic. Go to Article
*

Na2CrO4 Molar mass 161.97 g/mol Appearance yellow crystals Odor odorless Density 2.698 g/cm3 Melting point 792°C (1,458°F; 1,065K) (anhydrous) 20 °C (decahydrate)
31.8 g/100 mL (0 °C) 84.5 g/100 mL (25 °C) 126.7 g/100 mL (100 °C) Solubility slightly soluble in ethanol Solubility in methanol 0.344 g/100 mL (25 °C)
Carc. Cat. 2Muta. Cat. 2Repr. Cat. 2Very toxic (T+)Harmful (Xn)Corrosive (C)Dangerous for the environment (N) R-phrases (outdated) R45, R46, R60, R61, R21, R25, R26, R34, R42/43, R48/23, R50/53 S-phrases (outdated) S53, S45, S60, S61 NFPA 704
Except where otherwise noted, data are given for materials in their standard state (at 25°C <77°F>, 100kPa).

You are watching: What is the formula for sodium chromate


Nverify(what isYN?) Infoboxreferences

Sodium chromate is the inorganic compound with the formula Na2CrO4. It exists as a yellow hygroscopic solid, which can form tetra-, hexa-, and decahydrates. It is an intermediate in the extraction of chromium from its ores. Sodium chromate, like other hexavalent chromium compounds, is toxic and carcinogenic.<1>


Production and reactivity

It is obtained on a vast scale by roasting chromium ores in air in the presence of sodium carbonate:

2Cr2O3 + 4 Na2CO3 + 3 O2 → 4 Na2CrO4 + 4 CO2

This process converts the chromium into a water-extractable form, leaving behind iron oxides. Typically calcium carbonate is included in the mixture to improve oxygen access and to keep silicon and aluminium impurities in an insoluble form. The process temperature is typically around 1100 C.<2> For lab and small scale preparations a mixture of chromite ore, sodium hydroxide and sodium nitrate reacting at lower temperatures may be used (even 350 C in the corresponding potassium chromate system).<3> Subsequent to its formation, the chromate salt is converted to sodium dichromate, the precursor to most chromium compounds and materials.<1> The industrial route to chromium(III) oxide involves reduction of sodium chromate with sulfur.

Acid-base behavior

It converts to sodium dichromate when treated with acids:

2 Na2CrO4 + 2HCl → Na2Cr2O7 + 2NaCl + H2O

Further acidification affords chromium trioxide:

Na2CrO4 + H2SO4 → CrO3 + Na2SO4 + H2O

Uses

Aside from its central role in the production of chromium from its ores, sodium chromate is used as a corrosion inhibitor in the petroleum industry.<1> It is also a dyeing auxiliary in the textile industry<1> and a wood preservative.<4> It is a diagnostic pharmaceutical in determining red blood cell volume.

See more: Super Smash Flash 2 Demo V0.8B, Super Smash Flash 2 Demo V0

<5>

In organic chemistry, sodium chromate is used as an oxidant, converting primary alcohols to carboxylic acids and secondary alcohols to ketones.<6>

See also


Substance of very high concernRestriction of Hazardous Substances DirectiveHydrogenHeliumBoronNitrogenOxygenFluorineMethaneMezzanineAtom

This article uses material from the Wikipedia article "Sodium chromate", which is released under the Creative Commons Attribution-Share-Alike License 3.0. There is a list of all authors in Wikipedia