Ammonium dichromate

Ammonium dichromate
Names
	IUPAC name Ammonium dichromate
	Other names Ammonium bichromate; Ammonium pyrochromate
Identifiers
CAS Number	7789-09-5 ;
3D model (JSmol)	Interactive image;
ChemSpider	23002 ;
ECHA InfoCard	100.029.221
PubChem CID	24600;
RTECS number	HX7650000;
UNII	5J18BP595G ;
UN number	1439
CompTox Dashboard (EPA)	DTXSID70872953 ;
	InChI InChI=1S/2Cr.2H3N.7O/h;;21H3;;;;;;;/q;;;;;;;;;2-1/p+2 Key: JOSWYUNQBRPBDN-UHFFFAOYSA-P ; InChI=1/2Cr.2H3N.7O/h;;21H3;;;;;;;/q;;;;;;;;;2-1/p+2/rCr2O7.2H3N/c3-1(4,5)9-2(6,7)8;;/h;2*1H3/q-2;;/p+2 Key: JOSWYUNQBRPBDN-RFRSXZKWAS;
	SMILES [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O.[NH4+].[NH4+];
Properties
Chemical formula	(NH4)2Cr2O7
Molar mass	252.063 g·mol−1
Appearance	Orange-red crystals
Odor	odorless
Density	2.150 g/cm3 (20 °C (68 °F; 293 K))
Melting point	170 °C (338 °F; 443 K) decomposes
Solubility in water	18.2 g/100ml (0 °C (32 °F; 273 K)); 35.6 g/100ml (20 °C (68 °F; 293 K)); 40.0 g/100ml (25 °C (77 °F; 298 K)); 156.0 g/100ml (100 °C (212 °F; 373 K));
Solubility in ethanol	soluble
Structure
Crystal structure	monoclinic
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H272, H301, H312, H314, H317, H330, H334, H340, H350, H360, H372, H410
Precautionary statements	P201, P202, P210, P220, P221, P260, P264, P270, P271, P272, P273, P280, P284, P301+P310+P330, P301+P330+P331, P303+P361+P353, P304+P340+P310, P305+P351+P338+P310, P308+P313, P333+P313, P342+P311, P363, P370+P378, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	4 1 3 OX
Autoignition; temperature	218 °C (424 °F; 491 K)
Threshold limit value (TLV)	0.0002 mg/m3 (as Cr(VI)) (TWA), 0.0005 mg/m3 (as Cr(VI)) (STEL), 1 mg/10m3 (as CrO3) (C)
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	53 mg/kg (Rat, oral); 1860 mg/kg (Rabbit, dermal);
LC50 (median concentration)	0.2 mg/L (200 mg/m3) - 4h (Rat, inhalation, dust / mist)
	NIOSH (US health exposure limits):
PEL (Permissible)	0.005 mg/m3 (as Cr)
REL (Recommended)	8 hours, 0.0002 mg/m3 (as Cr)
IDLH (Immediate danger)	15 mg/m3 (as Cr(VI))
Related compounds
Other cations	Sodium dichromate; Potassium 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

Ammonium dichromate is an inorganic compound with the formula (NH₄)₂Cr₂O₇. In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. It is a salt consisting of ammonium ions and dichromate ions.

Ammonium dichromate is used in demonstrations of tabletop "volcanoes". However, this demonstration has become unpopular due to concerns about the compound's carcinogenic nature. It has been used in pyrotechnics and in the early days of photography. It is also used in holography.