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Sodium dichromate dihydrate

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Sodium dichromate dihydrate Basic information
Sodium dichromate dihydrate Chemical Properties
  • Melting point:91 °C(lit.)
  • Boiling point:400°C
  • Density 2,348 g/cm3
  • vapor density 10 (vs air)
  • form Solid
  • color Red-orange
  • Specific Gravity2.348
  • OdorOdorless
  • PH Range3.5-4.0
  • Water Solubility 730 g/L (20 ºC)
  • Sensitive Hygroscopic
  • Merck 14,8609
  • CAS DataBase Reference7789-12-0(CAS DataBase Reference)
  • EPA Substance Registry SystemDisodium dichromate dihydrate (7789-12-0)
Safety Information
MSDS
Sodium dichromate dihydrate Usage And Synthesis
  • Chemical PropertiesOrange-yellow powder. Soluble in acids and hot water; insoluble in alcohol and ether.
  • Chemical PropertiesSodium chromate, including the hexahydrate, is yellow crystalline solids that can also be used in solution. Disodium dichromate (10588-01-9):
  • UsesIt is used in preparation of titrant in redox titrations.
  • DefinitionA 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 DescriptionSolid orange-yellow crystal or powder.
  • Air & Water ReactionsWater soluble (hot water).
  • Reactivity ProfileSodium 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.
  • HazardToxic by ingestion and inhalation.
  • Health HazardINHALATION: 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 ExposureUsed 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.
  • ShippingUN3087 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 MethodsCrystallise 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.
  • IncompatibilitiesAqueous 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
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