What Is Cobalt Chloride? CoCl2 Formula, Uses and Safety
Cobalt chloride usually refers to cobalt(II) chloride, an inorganic cobalt salt with the formula CoCl2. NIST identifies the anhydrous compound as CAS 7646-79-9 with molecular weight 129.839 g/mol. The frequently searched hexahydrate is a different material form—CoCl2·6H2O, CAS 7791-13-1 and 237.931 g/mol. A buyer should therefore specify the required hydrate state, CAS, formula, tests and intended process rather than using “cobalt chloride” alone.
Cobalt chloride identity at a glance
| Controlled name | Cobalt(II) chloride; cobalt dichloride |
|---|---|
| CAS Registry Number | 7646-79-9 (anhydrous identity) |
| Molecular formula | CoCl2 (source display may use Hill order Cl2Co) |
| Molecular weight | 129.839 g/mol (commonly rounded to 129.84) |
| Oxidation state | Cobalt(II), Co2+ |
| EC number | 231-589-4 |
| PubChem CID | 24288 |
| InChIKey | GVPFVAHMJGGAJG-UHFFFAOYSA-L |
| Distinct common hydrate | Cobalt chloride hexahydrate, CAS 7791-13-1, CoCl2·6H2O |
Identity references: NIST Chemistry WebBook, PubChem CID 24288 and the ECHA cobalt dichloride record. These records support public identity fields; they do not establish a current Longchang form, specification, assay, impurity profile, grade, lot result, availability or suitability.
What does CoCl2 mean?
CoCl2 represents one cobalt atom and two chlorine atoms in the formula unit, with cobalt in the +2 oxidation state. “Cobaltous chloride,” “cobalt(II) chloride” and “cobalt dichloride” are names associated with this identity. “Cobaltic chloride” or CoCl3 describes a different oxidation state and must not be used as a synonym in purchasing documents.
Is CAS 7646-79-9 the hexahydrate?
No. CAS 7646-79-9 identifies the anhydrous cobalt dichloride record. PubChem identifies cobalt chloride hexahydrate as CAS 7791-13-1 with formula CoCl2·6H2O and molecular weight 237.93 g/mol. Commercial descriptions sometimes mix the anhydrous CAS with a hydrate color or cobalt-content table, so the current supplier specification and lot COA must state the exact form and calculation basis.
For the full comparison, see Cobalt chloride anhydrous vs hexahydrate: formula, color and hydration.
Why can cobalt chloride change color?
Reference descriptions commonly associate less-hydrated cobalt chloride with blue tones and hydrated material with pink or magenta tones. The observed color can also depend on coordination, water activity, solvent, concentration, temperature and matrix. Color alone is therefore not a reliable CAS, hydrate, purity or release test. Use controlled identity methods, water or loss-on-drying controls, assay basis and an applicable lot COA.
What is cobalt chloride used for?
ECHA records industrial contexts involving metal surface treatment, inorganic pigments and frits, glass and ceramic ware, varistors, magnets and professional handling of humidity-indicator articles. These are evidence that the substance appears in reported use contexts—not permission, performance proof or a statement that a current Longchang lot is suitable for every process.
| Reported context | Qualification questions before use |
|---|---|
| Surface treatment or plating | Required cobalt source, hydrate state, solution chemistry, impurity limits, bath/process controls and regulatory obligations |
| Pigments, frits, glass or ceramics | Material form, thermal process, color target, contaminant limits, worker/environmental controls and end-market rules |
| Varistors or magnets | Particle/form requirements, metal impurities, process compatibility and finished-component qualification |
| Humidity-indicator articles | Exact formulation, article design, exposure scenario, safer-alternative review and market-specific restrictions |
| Catalyst, battery, reagent or synthesis input | Exact reaction/process evidence, form, methods, acceptance criteria and applicable quality/regulatory review |
ECHA use information is available in its cobalt dichloride use-context record. A use mention does not establish grade, legal authorization, safe conditions, output performance or product compatibility.
Safety and regulatory boundary
ECHA lists cobalt dichloride on the REACH Candidate List for carcinogenicity and reproductive toxicity and states that Candidate List entries cover anhydrous and hydrated forms. ECHA’s substance information also records harmonized health and environmental hazard classifications. This webpage is not an SDS and does not provide handling or first-aid instructions. Request the current supplier SDS and use it with the buyer’s site, process, exposure scenario, destination rules and risk assessment.
Review the current ECHA Candidate List and substance information for the exact regulatory context. A CAS match does not replace buyer legal, EHS or product-stewardship review.
Claims removed from the earlier pages
| Earlier statement | Why it is not retained | Evidence required before reuse |
|---|---|---|
| High purity, precise international specifications or multiple grades | No current controlled specification, methods or applicable lot evidence was shown | Approved current specification, methods, grade definition and lot COA |
| Reliable supply, consistent availability, competitive price or bulk delivery | No current inventory, capacity or dated quotation supported the promise | Current availability check and destination-specific quotation |
| Benefits in batteries, catalysts, electroplating, medical research, food packaging or Vitamin B12 production | Broad use lists omit material form, process, performance, exposure and market boundaries | Exact use dossier, current material evidence, process validation and jurisdiction review |
| Generic PPE, storage, first aid and disposal instructions | Controls depend on the current product SDS, exposure scenario and local procedure | Current supplier SDS and buyer site/process risk assessment |
Choose the next page by intent
- Use this page for “what is cobalt chloride,” CoCl2 naming, formula, CAS 7646-79-9, reported uses and the regulatory boundary.
- Use the anhydrous-versus-hexahydrate guide for CAS, formula, molecular-weight, color and hydration comparisons.
- Use the product page for current form, specification, method, lot, document, sample and quotation requests.
Request current Cobalt Chloride information
Open the Cobalt Chloride CAS 7646-79-9 product page to request exact form/hydrate confirmation, the current specification, analytical methods, applicable lot COA, SDS status, sample availability, packaging and commercial information.
Email info@longchangchemical.com with the required form, intended process, tests and limits, quantity, packaging, destination and document requirements.
Frequently asked questions
What is the chemical formula for cobalt chloride?
CoCl2 for anhydrous cobalt(II) chloride. The hexahydrate is CoCl2·6H2O.
What is the molar mass of CoCl2?
NIST reports 129.839 g/mol for anhydrous cobalt dichloride. The hexahydrate is 237.931 g/mol.
Is cobalt chloride safe?
Do not infer safety from a generic article. ECHA identifies serious health and environmental hazard classifications and Candidate List status. Use the current SDS and an applicable site/process risk assessment.
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