Product Overview
Sodium dichromate dihydrate (CAS 7789-12-0) is a powerful inorganic oxidizer supplied as a reddish to bright orange crystalline solid. It serves as a reliable source of hexavalent chromium ions for electroplating, metal finishing, chemical synthesis, and analytical work. This is a Class 5.1 oxidizer with subsidiary Class 6.1 toxicity — a product with serious regulatory and handling obligations at every stage of the supply chain.
Alliance Chemical offers sodium dichromate dihydrate in pack sizes from 2 lbs for bench-scale and analytical use up to 55 lbs for production-volume operations. Every shipment includes full DOT-compliant hazmat documentation.
Why This Product
Sodium dichromate dihydrate is the workhorse chromium compound in industrial oxidation chemistry. The dihydrate form is hygroscopic and highly water-soluble, which means it dissolves readily into plating baths, treatment solutions, and reaction media without extended mixing. That same hygroscopicity demands dry storage and sealed containers — once exposed to ambient moisture, the crystals absorb water and can cake or form concentrated surface solutions.
For buyers choosing between sodium dichromate and other chromium sources: dichromate delivers a strong oxidizing potential that few alternatives match in metal finishing and synthesis applications. The trade-off is a demanding hazard profile — this material carries GHS classifications for carcinogenicity, mutagenicity, reproductive toxicity, and acute toxicity (per the product's GHS classification). Facilities using it must maintain rigorous exposure controls, waste handling, and regulatory compliance programs.
Chemical Profile
Sodium dichromate dihydrate has the molecular formula Cr₂H₄Na₂O₉ and a molecular weight of 298.00 g/mol. It presents as reddish to bright orange, odorless crystals that are hygroscopic and highly soluble in water, with moderate solubility in some organic solvents. The solid form is somewhat deliquescent — it will attract and absorb moisture from the air under typical warehouse conditions. CAS number 7789-12-0 identifies the dihydrate specifically.
Industrial Applications
Sodium dichromate dihydrate is established across several industrial sectors where its oxidizing strength and chromium content are essential:
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Electroplating and Metal Finishing — Dichromate ions supply the chromium source in hard chrome and decorative chrome plating baths. The compound also serves in chromate conversion coatings and passivation treatments that protect metal surfaces against corrosion.
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Chemical Synthesis — Functions as a powerful oxidizing agent in organic and inorganic reactions, converting alcohols to aldehydes and ketones, and participating in various industrial synthesis pathways where controlled oxidation is required.
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Analytical Chemistry — Used as a primary standard and titrant in quantitative analysis, particularly in dichromate titrations (dichrometry) for determining iron content, COD measurements, and other redox assays.
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Water Treatment — Applied in certain industrial water treatment processes to address specific contaminants through oxidation. Facilities using dichromate in water treatment must manage the resulting chromium-bearing waste streams under applicable environmental regulations.
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Dye and Pigment Manufacturing — Acts as a mordant in textile dyeing and as a precursor in the production of chromium-based pigments such as chrome yellow and chrome green.
Handling & Storage
Sodium dichromate dihydrate carries a Danger signal word (per the product's GHS classification) with an extensive hazard profile that demands strict controls:
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H272 — May intensify fire; oxidizer
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H301 — Toxic if swallowed
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H312 — Harmful in contact with skin
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H314 — Causes severe skin burns and eye damage
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H317 — May cause an allergic skin reaction
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H330 — Fatal if inhaled
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H334 — May cause allergy or asthma symptoms or breathing difficulties if inhaled
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H340 — May cause genetic defects
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H350 — May cause cancer
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H360FD — May damage fertility; may damage the unborn child
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H372 — Causes damage to organs through prolonged or repeated exposure
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H400 — Very toxic to aquatic life
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H410 — Very toxic to aquatic life with long lasting effects
PPE requirements: Chemical-resistant gloves, splash-proof safety goggles, and respiratory protection rated for chromium(VI) compounds are the minimum. Work in well-ventilated areas or under local exhaust ventilation. Full-face respirator or supplied air may be required depending on the operation and airborne concentration.
Storage: Keep in tightly sealed HDPE or glass containers in a cool, dry, well-ventilated area. This material is an oxidizer — store away from reducing agents, organic materials, combustibles, and strong acids. The hygroscopic nature of the dihydrate means containers must remain sealed when not in use to prevent caking and surface moisture accumulation. Avoid exposure to light for long-term storage integrity.
Incompatibilities: Reducing agents, organic solvents, combustible materials, strong acids, and finely divided metals. As a strong oxidizer, contact with incompatible materials can cause fire or violent reaction.
Hazmat & Shipping
Sodium dichromate dihydrate is a fully regulated hazardous material for transport. Every shipment from Alliance Chemical ships with proper DOT hazmat documentation, markings, and packaging.
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UN Number: UN3087 (per 49 CFR 172.101)
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Hazard Class: 5.1 — Oxidizer, with subsidiary hazard 6.1 — Toxic (per 49 CFR 172.101)
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Packing Group: II (per 49 CFR 172.101)
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Proper Shipping Name: Oxidizing solid, toxic, n.o.s. (Sodium dichromate dihydrate) (per 49 CFR 172.101)
The dual-hazard classification (oxidizer + toxic) affects carrier routing, packaging requirements, and quantity limits per vehicle. Plan accordingly when ordering production volumes.
Documentation
A Safety Data Sheet (SDS) ships with every order, available in English, Spanish, French, and Japanese. A Technical Data Sheet (TDS) and lot-specific Certificate of Analysis (COA) are also available — request the COA at the time of order to receive analytical data matched to your specific lot.
Why Buy from Alliance Chemical
This product ships as a Class 5.1/6.1 dual-hazard material — every order leaves our Taylor, TX facility with correct UN3087 packaging, marking, labeling, and shipping papers prepared under DOT Hazmat Specialist review. Alliance Chemical has been shipping industrial chemicals since 1998, serving over 50,000 customers across sectors that rely on regulated materials handled right the first time. Shipping and handling guidance on this page has been reviewed by Andre Taki, DOT Hazmat Specialist.
