Ammonium dichromate

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).

The Uses of Ammonium dichromate

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.

The Uses of Ammonium dichromate

It is used in oxidimetric standard.

The Uses of Ammonium dichromate

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.

The Uses of Ammonium dichromate

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.

What are the applications of Application

Ammonium dichromate is a dichromate salt oxidant for reactions with reducing agents

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.