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Send EmailSodium Bichromate, Sodium Dichromate, 10588-01-9, 7789-12-0
SODIUM DICHROMATE (Na₂Cr₂O₇)
Sodium Bichromate / Disodium Dichromate / Chromic Acid Disodium Salt
CAS Numbers: 10588-01-9 (Anhydrous), 7789-12-0 (Dihydrate)
EC Number: 234-190-3
1. IDENTIFICATION
| Property | Information |
|---|---|
| Chemical Name | Sodium Dichromate |
| Synonyms | Sodium bichromate, Disodium dichromate, Chromic acid disodium salt, Dichromic acid disodium salt, Sodium dichromate(VI) |
| Chemical Formula | Na₂Cr₂O₇ |
| Molecular Weight (Anhydrous) | 261.97 g/mol |
| Molecular Weight (Dihydrate) | 298.00 g/mol |
| CAS Numbers | 10588-01-9 (Anhydrous) 7789-12-0 (Dihydrate) |
| EC Number (EINECS) | 234-190-3 |
| Appearance | Orange-red to red crystalline solid |
| Odor | Odorless |
2. PHYSICAL PROPERTIES
| Property | Anhydrous | Dihydrate |
|---|---|---|
| Physical State (20°C) | Solid (crystalline) | Solid (crystalline) |
| Appearance | Orange-red to red crystals | Orange-red to red crystals |
| Odor | Odorless | Odorless |
| Molecular Weight | 261.97 g/mol | 298.00 g/mol |
| Density (20°C) | 2.35 g/cm³ | 2.52 g/cm³ |
| Bulk Density | 1.0 – 1.3 g/cm³ | 1.0 – 1.3 g/cm³ |
| Melting Point | 356.5 °C (674 °F) | 100 °C (loses water) |
| Boiling Point | 400 °C (752 °F) – decomposes | Decomposes on heating |
| Solubility in Water (25°C) | Very high – 185 g/100 mL | Very high |
| Solubility in Methanol | Soluble | Soluble |
| Solubility in Ethanol | Soluble | Soluble |
| pH (1% solution) | 3.5 – 4.5 (acidic) | 3.5 – 4.5 (acidic) |
| Hygroscopicity | Hygroscopic (absorbs moisture) | Slightly efflorescent |
| Vapor Pressure | Negligible | Negligible |
3. CHEMICAL PROPERTIES
| Property | Information |
|---|---|
| Chemical Formula | Na₂Cr₂O₇ |
| Molecular Weight | 261.97 g/mol |
| Chromium (Cr) Content | ~39.7% |
| Oxidation State | Cr(VI) (hexavalent chromium) – highly toxic |
| pH (1% solution) | 3.5 – 4.5 (acidic) |
| Stability | Stable under normal conditions |
| Oxidizing Properties | Very strong oxidizer |
| Reaction with Organics | Violent reactions, may cause fire or explosion |
| Reaction with Acids | Forms chromic acid (H₂Cr₂O₇) |
| Reaction with Reducing Agents | Reduced to Cr(III) compounds |
| Incompatible Materials | Organic materials, reducing agents, combustible materials, strong acids, metals |
Reaction with Organics (Oxidation):
Na₂Cr₂O₇ + Organic compounds + H₂SO₄ → Cr³⁺ + CO₂ + H₂O + Na₂SO₄
Dichromate – Chromate Equilibrium in Water:
Cr₂O₇²⁻ + H₂O ⇌ 2 CrO₄²⁻ + 2 H⁺ (orange) (yellow)
4. TYPES & GRADES
| Grade | Form | Purity | Applications |
|---|---|---|---|
| Technical Grade | Anhydrous or Dihydrate | ≥ 99.0% | Industrial applications (pigments, tanning, wood preservation) |
| Reagent Grade | Anhydrous | ≥ 99.5% | Laboratory, analytical chemistry |
| High Purity Grade | Anhydrous | ≥ 99.9% | Specialty applications, research |
5. PRODUCTION PROCESS
| Stage | Description |
|---|---|
| 1. Raw Material | Chromite ore (FeCr₂O₄) or sodium chromate (Na₂CrO₄) |
| 2. Roasting | Chromite ore is roasted with sodium carbonate (Na₂CO₃) and lime at high temperatures |
| 3. Leaching | Roasted product is leached with water to extract sodium chromate |
| 4. Acidification | Sodium chromate solution is acidified with sulfuric acid (H₂SO₄) |
| 5. Reaction | 2 Na₂CrO₄ + H₂SO₄ → Na₂Cr₂O₇ + Na₂SO₄ + H₂O |
| 6. Crystallization | Sodium dichromate crystallizes (sodium sulfate remains in solution) |
| 7. Centrifugation | Crystals are separated |
| 8. Drying | For anhydrous form, dihydrate is dried at elevated temperatures |
| 9. Packaging | Product is packaged |
Reaction Equations:
Roasting: 2 FeCr₂O₄ + 4 Na₂CO₃ + 7 O₂ → 4 Na₂CrO₄ + Fe₂O₃ + 4 CO₂↑
Acidification: 2 Na₂CrO₄ + H₂SO₄ → Na₂Cr₂O₇ + Na₂SO₄ + H₂O
6. APPLICATIONS
6.1. Production of Chromium Compounds (Largest Use – ~60%)
| Application | Function |
|---|---|
| Chromic Acid (H₂Cr₂O₇) Production | Raw material for chromic acid (electroplating, metal finishing) |
| Potassium Dichromate (K₂Cr₂O₇) Production | Raw material for potassium dichromate |
| Chromium Pigments | Chrome yellow (PbCrO₄), chrome orange, chrome green |
| Chromium Oxide Green (Cr₂O₃) | Pigment for ceramics, glass, paints |
| Basic Chromium Sulfate | For leather tanning |
6.2. Leather Tanning
| Application | Function |
|---|---|
| Chrome Tanning | Converted to basic chromium sulfate for leather tanning |
| Hide Processing | Provides softness, durability, and heat resistance to leather |
6.3. Wood Preservation
| Application | Function |
|---|---|
| Fungicide | Prevents wood rot and fungal decay |
| Insecticide | Protects against wood-boring insects (termites, beetles) |
| Wood Treatment | Pressure-impregnation of lumber for outdoor use |
| CCA Alternative | Component in some wood preservative formulations |
6.4. Textile Industry
| Application | Function |
|---|---|
| Dyeing Mordant | Fixes dyes to fabrics |
| Oxidation in Dyeing | Oxidizing agent in dyeing processes |
| Printing Pastes | Component in textile printing |
6.5. Corrosion Inhibition
| Application | Function |
|---|---|
| Cooling Water Systems | Corrosion inhibitor in recirculating cooling systems |
| Metal Treatment | Passivation of metal surfaces |
| Oil & Gas Pipelines | Corrosion protection |
6.6. Oil & Gas Drilling
| Application | Function |
|---|---|
| Drilling Fluids | Biocide to control bacteria and yeast (slime control) |
| Workover Fluids | Corrosion inhibitor |
6.7. Pigments & Paints
| Application | Function |
|---|---|
| Chrome Yellow Pigment | PbCrO₄ – yellow pigment for paints, plastics, inks |
| Chrome Orange Pigment | Orange pigment |
| Chrome Green Pigment | Mixed pigment |
| Glass Coloring | Green colorant for glass bottles and containers |
6.8. Match Manufacturing
| Application | Function |
|---|---|
| Match Head Composition | Oxidizing agent in match heads |
| Strike Surface | Component in striking surfaces |
6.9. Laboratory & Analytical Chemistry
| Application | Function |
|---|---|
| Oxidizing Agent | Laboratory oxidant for organic synthesis |
| Analytical Reagent | Titration (dichromatometry) – determination of iron |
| Cleaning Solution | Chromic acid cleaning solution for laboratory glassware |
6.10. Other Applications
| Application | Function |
|---|---|
| Fireworks | Oxidizing agent in pyrotechnics |
| Battery Manufacturing | Component in some battery types |
| Photography | Oxidizing agent in photographic processes |
| Ceramics | Colorant and flux |
| Ink Manufacturing | Component in some ink formulations |
| Wastewater Treatment | Reducing agent for chromium removal (as Cr(III) after reduction) |
7. QUALITY SPECIFICATIONS (TYPICAL – TECHNICAL GRADE)
| Parameter | Anhydrous | Dihydrate |
|---|---|---|
| Purity (Na₂Cr₂O₇) | ≥ 99.0% | ≥ 99.0% (as anhydrous equivalent) |
| Cr(VI) Content | ~39.7% | ~35.0% |
| Chlorides (Cl) | ≤ 0.01% | ≤ 0.01% |
| Sulfates (SO₄) | ≤ 0.10% | ≤ 0.10% |
| Iron (Fe) | ≤ 0.005% | ≤ 0.005% |
| Water Insolubles | ≤ 0.05% | ≤ 0.05% |
| pH (1% solution) | 3.5 – 4.5 | 3.5 – 4.5 |
| Moisture | ≤ 0.5% | – |
| Loss on Drying | – | 13 – 15% |
8. STORAGE & HANDLING
| Parameter | Information |
|---|---|
| Storage Conditions | Cool, dry, well-ventilated area |
| Container Requirements | Tightly closed, corrosion-resistant containers (HDPE, lined drums, stainless steel) |
| Protect From | Moisture (hygroscopic), organic materials, reducing agents, heat |
| Shelf Life | 12-24 months (when stored properly in unopened packaging) |
| Hygroscopicity | Hygroscopic – absorbs moisture from air |
| Incompatible Materials | Organic materials, reducing agents, combustible materials, strong acids, powdered metals |
| Packaging Options | 25 kg bags (lined), 50 kg drums (HDPE), 500 kg/1000 kg FIBC (big bags) |
9. SAFETY & HEALTH INFORMATION
GHS Classification
| Hazard Class | Category |
|---|---|
| Oxidizing Solids | Category 1 (H271) |
| Acute Toxicity (Oral) | Category 3 (H301) |
| Acute Toxicity (Inhalation) | Category 2 (H330) |
| Acute Toxicity (Dermal) | Category 3 (H311) |
| Skin Corrosion/Irritation | Category 1B (H314) |
| Serious Eye Damage | Category 1 (H318) |
| Respiratory Sensitization | Category 1 (H334) |
| Skin Sensitization | Category 1 (H317) |
| Germ Cell Mutagenicity | Category 1B (H340) |
| Carcinogenicity | Category 1A (H350) |
| Reproductive Toxicity | Category 2 (H361) |
| Specific Target Organ Toxicity (Repeated exposure) | Category 1 (H372) |
| Acute Aquatic Toxicity | Category 1 (H400) |
| Chronic Aquatic Toxicity | Category 1 (H410) |
Hazard Statements (H-Codes)
| Code | Statement |
|---|---|
| H271 | May cause fire or explosion; strong oxidizer |
| H301 | Toxic if swallowed |
| H311 | Toxic in contact with skin |
| H314 | Causes severe skin burns and eye damage |
| H317 | May cause an allergic skin reaction |
| H318 | Causes serious eye damage |
| H330 | Fatal if inhaled |
| H334 | May cause allergy or asthma symptoms if inhaled |
| H340 | May cause genetic defects |
| H350 | May cause cancer |
| H361 | Suspected of damaging fertility or the unborn child |
| H372 | Causes damage to organs through prolonged or repeated exposure |
| H400 | Very toxic to aquatic life |
| H410 | Very toxic to aquatic life with long-lasting effects |
Precautionary Statements (P-Codes)
| Code | Statement |
|---|---|
| P201 | Obtain special instructions before use |
| P202 | Do not handle until all safety precautions have been read and understood |
| P210 | Keep away from heat, sparks, open flames |
| P220 | Keep away from combustible materials |
| P260 | Do not breathe dust |
| P280 | Wear protective gloves, protective clothing, eye protection, face protection |
| P301+P310 | IF SWALLOWED: Immediately call a POISON CENTER |
| P302+P352 | IF ON SKIN: Wash with plenty of water |
| P304+P340 | IF INHALED: Remove person to fresh air |
| P305+P351+P338 | IF IN EYES: Rinse cautiously with water for several minutes |
| P308+P313 | IF exposed or concerned: Get medical advice |
| P501 | Dispose of contents/container in accordance with local regulations |
10. TOXICOLOGICAL INFORMATION
| Parameter | Value |
|---|---|
| Oral LD50 (rat) | ~50 mg/kg (highly toxic) |
| Dermal LD50 (rabbit) | ~100 mg/kg |
| Inhalation LC50 (rat) | ~0.1 mg/L (4 hours) |
| Carcinogenicity | IARC Group 1 (Carcinogenic to humans) |
| Mutagenicity | Positive – causes genetic mutations |
| Reproductive Toxicity | Suspected reproductive toxicant |
| Target Organs | Respiratory system, skin, eyes, kidneys, liver |
| Chronic Effects | Lung cancer, nasal septum perforation, dermatitis, kidney damage |
Health Effects:
-
Acute (Ingestion): Nausea, vomiting, diarrhea, abdominal pain, gastrointestinal bleeding, circulatory collapse, acute renal failure
-
Acute (Inhalation): Respiratory tract irritation, coughing, wheezing, pulmonary edema
-
Acute (Skin Contact): Severe burns, dermatitis, sensitization
-
Acute (Eye Contact): Severe burns, potential blindness
-
Chronic: Lung cancer, nasal ulcers and perforation, chronic dermatitis, kidney damage
11. FIRST AID MEASURES
| Exposure Route | Action |
|---|---|
| Inhalation | Remove to fresh air. Administer oxygen if breathing difficulty. Seek immediate medical attention. |
| Skin Contact | Remove contaminated clothing. Wash with plenty of water for at least 15 minutes. Seek medical attention. |
| Eye Contact | Rinse immediately with plenty of water for at least 15 minutes. Seek immediate medical attention. |
| Ingestion | Do NOT induce vomiting. Rinse mouth. Drink water. Seek immediate medical attention. |
12. FIRE FIGHTING MEASURES
| Parameter | Information |
|---|---|
| Fire Hazard | Strong oxidizer – may cause fire or explosion when in contact with combustible materials |
| Extinguishing Media | Water spray (large quantities), dry sand, CO₂ (for small fires) |
| Special Hazards | Decomposes when heated, releasing toxic chromium fumes and oxygen |
| Protective Equipment | Self-contained breathing apparatus (SCBA), full protective clothing |
13. ENVIRONMENTAL INFORMATION
| Parameter | Information |
|---|---|
| Aquatic Toxicity | Very toxic to aquatic life (fish, algae, invertebrates) |
| Persistence | Persistent in environment (Cr(VI) does not degrade) |
| Bioaccumulation | Moderate potential |
| Mobility in Soil | High (soluble in water) |
| Waste Disposal | Dispose as hazardous waste according to local regulations. Do not discharge into natural water bodies. |
14. TRANSPORT INFORMATION
| Parameter | Information |
|---|---|
| UN Number | 3087 |
| Hazard Class | 5.1 (Oxidizing substance) |
| Subsidiary Hazard | 6.1 (Toxic substance) |
| Packing Group | II |
| Proper Shipping Name | OXIDIZING SOLID, TOXIC, N.O.S. (Sodium dichromate) |
| Marine Pollutant | Yes |
| ADR/RID Label | 5.1 + 6.1 |
| EMS | F-A, S-Q |
15. REGULATORY INFORMATION
| Region | Status |
|---|---|
| EU | REACH registered; restricted under Annex XVII (SVHC – Substance of Very High Concern) |
| Turkey (KKDIK) | Mandatory compliance; requires registration |
| USA (TSCA) | Listed; subject to reporting under EPCRA Section 313 |
| Canada (DSL) | Listed |
| Australia (AICS) | Listed |
| Japan (ENCS) | Listed |
| Korea (KECL) | Listed |
| China (IECSC) | Listed |
| RoHS | Restricted in electrical and electronic equipment |
16. SYNONYMS & OTHER NAMES
| Turkish Name | English Name |
|---|---|
| Sodyum Bikromat | Sodium Dichromate |
| Sodyum Dikromat | Sodium Bichromate |
| Dikromik Asit Disodyum Tuzu | Dichromic Acid Disodium Salt |
| Soda Bikromat | Soda Bichromate |
| Ahşap Koruyucu | Wood Preservative |
| Kromik Asit Sodyum Tuzu | Chromic Acid Sodium Salt |
| Sodyum Dikromat Dihidrat | Sodium Dichromate Dihydrate |
Database Identifiers:
-
CAS (Anhydrous): 10588-01-9
-
CAS (Dihydrate): 7789-12-0
-
EC: 234-190-3
-
MDL: MFCD00003705
-
PubChem CID: 25408
-
RTECS: HX7700000
-
UN: 3087
17. COMPARISON: SODIUM DICHROMATE vs POTASSIUM DICHROMATE
| Property | Sodium Dichromate | Potassium Dichromate |
|---|---|---|
| Formula | Na₂Cr₂O₇ | K₂Cr₂O₇ |
| Molecular Weight | 261.97 | 294.18 |
| Cr(VI) Content | ~39.7% | ~35.4% |
| Solubility in Water (20°C) | 185 g/100 mL | 12 g/100 mL |
| Hygroscopicity | Hygroscopic | Not hygroscopic |
| Cost | Lower | Higher |
| Primary Use | Chrome chemicals, tanning | Analytical reagent, pyrotechnics |
18. SECTORAL COMPATIBILITY
| Sector | Suitability | Notes |
|---|---|---|
| Leather Tanning | High | Chrome tanning (via basic chromium sulfate) |
| Wood Preservation | High | Fungicide, insecticide |
| Pigments & Paints | High | Chrome yellow, chrome orange pigments |
| Textile | High | Mordant, dyeing oxidizer |
| Oil & Gas | High | Biocide in drilling fluids |
| Corrosion Inhibition | High | Cooling water systems |
| Match Manufacturing | High | Oxidizing agent |
| Laboratory | High | Analytical reagent, oxidizing agent |
| Glass & Ceramics | High | Colorant |
| Cosmetics | Banned | Not permitted due to toxicity |
| Food | Banned | Not permitted |
| Pharmaceutical | Banned | Not permitted |
19. SUMMARY
Sodium Dichromate (Na₂Cr₂O₇, CAS 10588-01-9) is an orange-red, crystalline, highly toxic, and strong oxidizing agent containing hexavalent chromium (Cr(VI)). It is classified as a Group 1 carcinogen and is extremely hazardous to human health and the environment.
Key Features:
| Feature | Value |
|---|---|
| Appearance | Orange-red crystalline solid |
| Molecular Weight | 261.97 g/mol |
| Density | 2.35 g/cm³ |
| Melting Point | 356.5°C |
| Solubility | Very high in water (185 g/100 mL at 25°C) |
| Oxidizing Class | Strong oxidizer (UN 3087, Class 5.1 + 6.1) |
Main Application Areas:
| Sector | Applications |
|---|---|
| Leather Tanning | Chrome tanning (via basic chromium sulfate) |
| Wood Preservation | Fungicide, insecticide |
| Pigments | Chrome yellow, chrome orange, chrome green |
| Textile | Mordant, dyeing oxidizer |
| Oil & Gas | Biocide in drilling fluids |
| Corrosion Inhibition | Cooling water systems |
| Match Manufacturing | Oxidizing agent |
| Laboratory | Analytical reagent |
Key Safety Points:
-
CARCINOGEN (Category 1A) – May cause cancer (lung cancer)
-
MUTAGEN – May cause genetic defects
-
TOXIC – Fatal if swallowed, inhaled, or in contact with skin
-
CORROSIVE – Causes severe skin burns and eye damage
-
ENVIRONMENTAL HAZARD – Very toxic to aquatic life
-
HANDLE WITH EXTREME CAUTION – Use full PPE, adequate ventilation
20. IMPORTANT NOTES & DISCLAIMER
-
Hexavalent Chromium (Cr(VI)) Hazard: Sodium dichromate contains hexavalent chromium, which is classified as a Group 1 carcinogen (carcinogenic to humans) by IARC. It is associated with lung cancer, nasal septum perforation, and skin ulcers.
-
Strong Oxidizer: Sodium dichromate is a very strong oxidizer. Keep away from organic materials, reducing agents, and combustible materials – may cause fire or explosion.
-
Environmental Persistence: Cr(VI) does not degrade in the environment. It is highly mobile in water and toxic to aquatic life. Spills must be contained and treated immediately.
-
Regulatory Restrictions: Sodium dichromate is restricted under REACH (EU), RoHS, and many national regulations. It is listed as a Substance of Very High Concern (SVHC). Its use is banned in cosmetics, food, and pharmaceuticals.
-
Alternatives: Due to toxicity concerns, many applications are moving to alternative chemicals:
-
Leather tanning: Alternative tanning agents (synthetic tannins, aluminum, zirconium, titanium salts)
-
Corrosion inhibition: Molybdate-based inhibitors
-
Wood preservation: Copper-based preservatives (e.g., copper azole)
-
-
Leather Tanning: In the leather industry, sodium dichromate is not used directly. It is first reduced to basic chromium sulfate (Cr(III)), which is used for chrome tanning. Cr(III) is significantly less toxic than Cr(VI).
-
Chromic Acid Cleaning Solution: "Chromic acid" cleaning solution (sodium dichromate + sulfuric acid) is used for cleaning laboratory glassware. This solution is highly corrosive, toxic, and carcinogenic. Alternative cleaning solutions (detergents, NOCHROMIX) are preferred.
-
Personal Protective Equipment: When handling sodium dichromate, always use:
-
Nitrile or neoprene gloves (not latex)
-
Chemical safety goggles + face shield
-
Full protective clothing
-
Respiratory protection (N100 or P100 respirator)
-
-
Decontamination: Spills should be treated with reducing agents (sodium bisulfite, sodium metabisulfite, ferrous sulfate) to reduce Cr(VI) to Cr(III) before cleanup.
-
Medical Surveillance: Workers handling chromium(VI) compounds should undergo regular medical surveillance, including lung function tests, skin examinations, and nasal septum inspections.
Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS) provided by the manufacturer/supplier. Sodium dichromate is a highly hazardous substance. Extreme care must be taken during handling, storage, and disposal.
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