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Sodium dichromate dihydrate

Sodium dichromate dihydrate
Sodium dichromate dihydrate structure
CAS No.
7789-12-0
Chemical Name:
Sodium dichromate dihydrate
Synonyms
SODIUM BICHROMATE;SODIUM DICHROMATE;SODIUM DICHROMATE GR;Sodium dichromate di;SODIUM DICHROMATE 2H2O;SODIUM DICHROMATE, ACS;Sodiumbichromateanhydrous;SODIUM DICHROMATE, HYDROUS;SODIUM DICHROMATE 2HYD XTL;SODIUM DICHROMATE DIHYDRATE
CBNumber:
CB2206099
Molecular Formula:
Cr2H4Na2O9
Formula Weight:
298
MOL File:
7789-12-0.mol

Sodium dichromate dihydrate Properties

Melting point:
91 °C(lit.)
Boiling point:
400°C
Density 
2,348 g/cm3
form 
Solid
Specific Gravity
2.348
color 
Red-orange
Water Solubility 
730 g/L (20 ºC)
Sensitive 
Hygroscopic
Merck 
14,8609
CAS DataBase Reference
7789-12-0(CAS DataBase Reference)
EPA Substance Registry System
Chromic acid (H2Cr2O7), disodium salt, dihydrate(7789-12-0)
SAFETY
  • Risk and Safety Statements
Symbol(GHS) 
GHS03,GHS05,GHS06,GHS08,GHS09
Hazard statements  H272-H301-H312-H314-H317-H330-H334-H340-H350-H360-H372-H400-H410
Precautionary statements  P221-P301+P310a-P303+P361+P353-P304+P340-P305+P351+P338-P320-P405-P501a
Hazard Codes  O,T+,N
Risk Statements  45-46-60-61-8-21-25-26-34-42/43-48/23-50/53
Safety Statements  53-45-60-61
RIDADR  UN 3086 6.1/PG 1
WGK Germany  3
RTECS  HX7750000
TSCA  Yes
HazardClass  5.1
PackingGroup  III
HS Code  28413000

Sodium dichromate dihydrate Chemical Properties,Uses,Production

Chemical Properties

Orange-yellow powder. Soluble in acids and hot water; insoluble in alcohol and ether.

Chemical Properties

Sodium chromate, including the hexahydrate, is yellow crystalline solids that can also be used in solution. Disodium dichromate (10588-01-9):

Uses

It is used in preparation of titrant in redox titrations.

Definition

A red crystallinesolid, Na2Cr2O7.2H2O, solublein water and insoluble in ethanol. Itis usually known as the dihydrate(r.d. 2.52), which starts to lose waterabove 100°C; the compound decomposesabove 400°C. It is made bymelting chrome iron ore with limeand soda ash and acidification of thechromate thus formed. Sodiumdichromate is cheaper than the correspondingpotassium compound buthas the disadvantage of being hygroscopic.It is used as a mordant in dyeing,as an oxidizing agent in organicchemistry, and in analytical chemistry.

General Description

Solid orange-yellow crystal or powder.

Air & Water Reactions

Water soluble (hot water).

Reactivity Profile

Sodium dichromate dihydrate can react with reducing agents to generate heat and products that may be gaseous (causing pressurization of closed containers). The products may themselves be capable of further reactions (such as combustion in the air). Reactions may be rapid but often requires initiation (heat, spark, catalyst, addition of a solvent). Can react violently with active metals, cyanides, esters, and thiocyanates.

Hazard

Toxic by ingestion and inhalation.

Health Hazard

INHALATION: Corrosive to mucous membranes continuous exposure may lead to perforation of nasal septum. EYES: Conjunctivitis and lacrimation. SKIN: Corrosive producing deep penetrating ulcers to exposed area. Slow to heal. INGESTION: Has a harsh metallic taste. May cause vertigo, thirst, abdominal pain, vomiting, shock, convulsions and coma.

Potential Exposure

Used to make dyes, inks, pigments, and other chromates; in leather tanning, a corrosion inhibitor in circulating water systems; metal treatment; a drilling mud additive; chemical intermediate for chromium catalysts; colorimetry, oxidizing agent; bleaching agent; an algicide, fungicide, insecticide; in wood preservation.

Shipping

UN3087 Oxidizing solid, toxic, n.o.s., Hazard Class: 5.1; Labels: 5.1-Oxidizer, 6.1-Poisonous materials, Technical Name Required. UN3085 Oxidizing solid, corrosive, n.o.s., Hazard Class: 5.1; Labels: 5.1-Oxidizer, 8-Corrosive material, Technical Name Required.

Purification Methods

Crystallise the dichromate from small volumes of H2O by evaporation to crystallisation. Its solubility in H2O is 238% at 0o and 508% at boiling. The red dihydrate is slowly dehydrated by heating at 100o for long periods. It is deliquescent and is a powerful oxidising agent—do not place it in contact with skin— wash immediately as it is caustic. (Possible carcinogen.) Sodium dihydrogen orthophosphate ( 2 H2O) [13472-35-0 (2H2O), 10049-21-5 (H2O), 7558-80-7 (anhydrous)] M 156.0, m 60o(dec), d 4 1.91. Crystallise it from warm water (0.5mL/g) by chilling.

Incompatibilities

Aqueous solution in a base. A strong oxidizer. Violent reaction with reducing agents; combustibles, strong acids; organic materials.

Sodium dichromate dihydrate Preparation Products And Raw materials

Raw materials

Preparation Products


Sodium dichromate dihydrate Spectrum


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