Ammonium chromate

Ammonium chromate is a salt with the formula (NH₄)₂CrO₄. It forms yellow, monoclinic crystals; made from ammonium hydroxide and ammonium dichromate; used in photography as a sensitizer for gelatin coatings. It is often used in photography, textile printing, and fixing chromate dyes on wool. It is also used as an analytical reagent, catalyst, and corrosion inhibitor. It is soluble in water, and, when applied, can cause irritation in the mucous membrane, eyes, respiratory tract, skin, etc. It may cause skin sensitization after prolonged contact. It is also known to be carcinogenic (cancer-causing), and it can cause tissue ulceration and injury to the liver and kidneys.^[4]

Ammonium chromate

Names
Other names Ammonium chromate(IV)
Identifiers
CAS Number	7788-98-9
3D model (JSmol)	Interactive image
ChemSpider	22997
ECHA InfoCard	100.029.217
EC Number	232-138-4
PubChem CID	24595
UNII	X7I33TTT6D
UN number	3085,3077
CompTox Dashboard (EPA)	DTXSID3064857
InChI InChI=1S/Cr.2H3N.4O/h;2*1H3;;;;/q;;;;;2*-1/p+2 Key: MFFLHUNPSHBKRG-UHFFFAOYSA-P
SMILES [NH4+].[NH4+].[O-][Cr](=O)(=O)[O-]
Properties
Chemical formula	(NH4)2CrO4
Molar mass	152.07 g/mol
Appearance	yellow crystals
Density	1.90 g/ml
Melting point	185 °C (365 °F; 458 K) decomposes[1]
Solubility in water	24.8 g/100ml (0 °C) 37.36 g/100ml (25 °C)[1] 45.3 g/100ml (40 °C) 70.06 g/100ml (75 °C)[1][2]
Thermochemistry
Std molar entropy (S⦵298)	657 J/K·mol
Std enthalpy of formation (ΔfH⦵298)	−1163 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Toxic
GHS labelling:
Pictograms	[3]
Signal word	Danger
Hazard statements	H272, H314, H317, H334, H350, H400[3]
Precautionary statements	P201, P220, P261, P273, P280, P305+P351+P338[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

See also

• Ammonium dichromate