Sodium dichromate

Sodium dichromate
Names
	IUPAC name Sodium dichromate
	Other names Chromic acid disodium salt
Identifiers
CAS Number	10588-01-9 ; 7789-12-0 (dihydrate) ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:39483 ;
ChemSpider	23723 ;
ECHA InfoCard	100.031.070
EC Number	234-190-3;
Gmelin Reference	21597
PubChem CID	25408;
RTECS number	HX7750000; HX7750000 (dihydrate);
UNII	C9G6VY6ZZ4 ; 52125XYY2A (dihydrate) ;
UN number	3288
CompTox Dashboard (EPA)	DTXSID8021274 ;
	InChI InChI=1S/2Cr.2Na.7O/q;;2+1;;;;;;2-1 Key: KIEOKOFEPABQKJ-UHFFFAOYSA-N ; InChI=1/2Cr.2Na.7O/q;;2+1;;;;;;2-1/rCr2O7.2Na/c3-1(4,5)9-2(6,7)8;;/q-2;2*+1 Key: KIEOKOFEPABQKJ-RXLKZJBDAW;
	SMILES [Na+].[Na+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O;
Properties
Chemical formula	Na2Cr2O7
Molar mass	261.97 g/mol (anhydrous); 298.00 g/mol (dihydrate)
Appearance	bright orange
Odor	odorless
Density	2.52 g/cm3
Melting point	356.7 °C (674.1 °F; 629.8 K)
Boiling point	400 °C (752 °F; 673 K) decomposes
Solubility in water	73 g/100 mL at 25 °C
Solubility in other solvents	soluble in methanol, ethanol
Refractive index (nD)	1.661 (dihydrate)
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H272, H301, H312, H314, H317, H330, H334, H340, H350, H360, H372, H410
Precautionary statements	P201, P202, P210, P220, P221, P260, P261, P264, P270, P271, P272, P273, P280, P281, P284, P285, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P304+P341, P305+P351+P338, P308+P313, P310, P312, P314, P320, P321, P322, P330, P333+P313, P342+P311, P363, P370+P378, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	4 0 1 OX
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	50 mg/kg
Safety data sheet (SDS)	ICSC 1369
Related compounds
Other anions	Sodium chromate; Sodium molybdate; Sodium tungstate
Other cations	Potassium dichromate; Ammonium dichromate
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Sodium dichromate is the inorganic compound with the formula Na₂ Cr₂ O₇. However, the salt is usually handled as its dihydrate Na₂Cr₂O₇·2H₂O. Virtually all chromium ore is processed via conversion to sodium dichromate and virtually all compounds and materials based on chromium are prepared from this salt.^[1] In terms of reactivity and appearance, sodium dichromate and potassium dichromate are very similar. The sodium salt is, however, around twenty times more soluble in water than the potassium salt (49 g/L at 0 °C) and its equivalent weight is also lower, which is often desirable.^[2]

^ Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger, "Chromium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_067
^ Freeman, F. "Sodium Dichromate" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289X.

[Ullmann-1] Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger, "Chromium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_067

[eEROS-2] Freeman, F. "Sodium Dichromate" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289X.

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