Ammonium dichromate Property

Melting point:

170 °C (dec.)(lit.)

Density 

2.150

vapor density 

8.7 (vs air)

solubility 

H₂O: 1 M at 20 °C, clear, colorless

form 

Solid

color 

Orange to red

Odor

Odorless

PH Range

3 - 4

Water Solubility 

360 g/L (20 ºC)

Decomposition 

170 °C

Merck 

14,515

Exposure limits

ACGIH: TWA 0.0002 mg/m3; STEL 0.0005 mg/m3 (Skin)
OSHA: Ceiling 0.1 mg/m3
NIOSH: IDLH 15 mg/m3; TWA 0.0002 mg/m3

Stability:

Stability Strong oxidizer - contact with flammable materials may cause fire. Reactions carried out in closed vessels may lead to explosion. Incompatible with organic materials, strong reducing agents.

CAS DataBase Reference

7789-09-5(CAS DataBase Reference)

EPA Substance Registry System

Ammonium dichromate(VI) (7789-09-5)

Safety

Hazard Codes 

E,T+,N

Risk Statements 

45-46-60-61-2-8-21-25-26-34-42/43-48/23-50/53

Safety Statements 

53-45-60-61

RIDADR 

UN 1439 5.1/PG 2

WGK Germany 

3

RTECS 

HX7650000

Autoignition Temperature

218°C

TSCA 

Yes

HazardClass 

5.1

PackingGroup 

II

HS Code 

28415000

Hazardous Substances Data

7789-09-5(Hazardous Substances Data)

Toxicity

LDLo scu-gpg: 25 mg/kg EQSSDX 1,1,75

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H272May intensify fire; oxidizer

H301Toxic if swalloed

H312Harmful in contact with skin

H314Causes severe skin burns and eye damage

H317May cause an allergic skin reaction

H330Fatal if inhaled

H334May cause allergy or asthma symptoms or breathing difficulties if inhaled

H340May cause genetic defects

H350May cause cancer

H360May damage fertility or the unborn child

H372Causes damage to organs through prolonged or repeated exposure

H410Very toxic to aquatic life with long lasting effects

Precautionary statements

P210Keep away from heat/sparks/open flames/hot surfaces. — No smoking.

P260Do not breathe dust/fume/gas/mist/vapours/spray.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P303+P361+P353IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

Ammonium dichromate Chemical Properties,Usage,Production

Description

Ammonium dichromate is a salt consisting of ammonium ions and dichromate ions. It can be used as in pyrotechinics, photography as well as lithography. It can be used as a catalyst and a source of pure nitrogen in the laboratory. It can also be used as the mordant of dyeing pigment. It has application in the manufacturing of alizarin, chrome alum, leather tanning and oil purification. Moreover, it can be used for the production of phosphor raster of television screen through acting as the photoactive site. Finally, there are also reports using it for combustion synthesis of perovskite LnCrO3 powder and oxidation of hydroquinones, catechols and phenols.

References

Havard, Jennifer M., et al. "Design of Photoresists with Reduced Environmental Impact. 1. Water-Soluble Resists Based on Photo- Cross-Linking of Poly(vinyl alcohol)." Plos One 8.4(1999):-.
Kingsley, J. J., and L. R. Pederson. "Combustion synthesis of perovskite LnCrO3 powders using ammonium dichromate." Materials Letters 18.1-2 (1993): 89-96.
Fischer, Alfred, and George N. Henderson. "Oxidation of hydroquinones, catechols, and phenols using ceric ammonium nitrate and ammonium dichromate coated on silica: an efficient and convenient preparation of quinones." Synthesis 1985.6/7 (1985): 641 -643.
Suzuki, S. "Determination of Chromium Atom Density on Deep UV Exposed Ammonium-Dichromated Gelatin Films with Ultraviolet Absorption Spectra." Journal of the Electrochemical Society135.10 (1988):2615-2620.

Chemical Properties

bright orange-red crystals

Chemical Properties

Ammonium dichromate is a combustible, orange-red crystalline solid which is used in solution.

Occurrence

Bright orange-red monoclinic crystals; odorless; hygroscopic; decomposes at 180°C; density 2.115 g/cm³ at 25°C; readily dissolves in water (26.67 g/100 g at 20°C).

Uses

Ammonium dichromate is used in photo engraving, dye mordant, pigments, pickling, photography, process engraving, lithography, pyrotechnics, glazes for porcelain and china wares. It acts as a catalyst and a source of nitrogen in the laboratory and as the photoactive site. It is also used in the preparation of alizarin and chrome alum. Further, it is used in leather and oil industry for tanning and purification respectively. It is involved in the production of the phosphor raster television screens and other devices.

Uses

Yellow needles made by chromic acid acting on ammonium hydroxide. The product is produced by crystallization. Ammonium dichromate was used interchangeably with potassium dichromate for sensitizing gelatin, albumen, gums, and other colloids that were used for pigment processes. Ammonium dichromate is more sensitive than the potassium alternative.

Uses

It is used in oxidimetric standard.

Uses

Source of pure nitrogen (esp in the laboratory); in pyrotechnics (Vesuvius fire); in lithography and photo engraving; in special mordant, catalysts, and porcelain finishes; intermediate in the manufacture of pigments; of magnetic recording materials.

General Description

Ammonium dichromate is a bright orange red crystalline solid. Ammonium dichromate is readily ignited and burns producing a voluminous green residue. If heated in a closed container, the container may rupture due to the decomposition of the material. Ammonium dichromate may also act as a strong oxidizing agent if mixed with or contaminated with combustible material. Ammonium dichromate is soluble in water.

Air & Water Reactions

Water soluble.

Reactivity Profile

Ammonium dichromate is an oxidizing reagent, Ammonium dichromate readily reacts with reducing materials, in large quantity Ammonium dichromate may produce a violent reaction. Direct exposure to heat or shock will explode it. When heated to decomposition Ammonium dichromate emits toxic fumes of ammonia and nitrogen oxides [Sax, 9th ed., 1996, p. 205].

Hazard

Dusts and solutions are toxic, irritating to eyes and skin; dangerous fire risk. Strong oxidizing agent may explode in contact with organic materi- als. TLV: 0.05 mg(Cr)/m 3 ; Confirmed human car- cinogen.

Health Hazard

Inhalation causes irritation or ulceration of the mucous membranes of the nose, throat or respiratory tract. Respiratory irritation can produce symptoms resembling those of asthma. Continuing irritation of the nose may lead to perforation of the nasal septum. External contact can cause eye irritation and conjunctivitis, irritation and ulceration of skin wounds, and rash or external ulcers. If ingested, irritates mucous membrane and causes vomiting.

Safety Profile

Confirmed human carcinogen. Poison by inhalation, ingestion, skin contact, and subcutaneous routes. See also CHROMIUM COMPOUNDS. An unstable oxidizer. Moderately flammable; reacts with reducing agents.

Potential Exposure

It is used in dyeing, leather tanning and to make fireworks and chromic oxide; in lithography and photoengraving; in manufacture of special mordants and catalysts.

Shipping

UN1439 Ammonium dichromate, Hazard Class: 5.1; Labels: 5.1-Oxidizer.

Purification Methods

It crystallises from weak aqueous HCl (ca 1mL/g). It decomposes rapidly on heating. (Possible carcinogen and is POISONOUS)

Incompatibilities

An unstable oxidizer; freezing/melting point5(decomposes below MP) 180 C; decomposition becomes self-sustaining and violent at about 225 C. Contact with combustible, organic or other easily oxidized materials, strong acids; hydrazine and other reducing agents; alcohols, sodium nitrite may cause fire and explosions.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Add a large volume of a reductant solution (hypo, bisulfite or ferrous salt and acidify with sulfuric acid). Neutralize when reduction is complete and flush to sewer with large volume of water.