CAS 7758-94-3 identifies iron(II) chloride, also called ferrous chloride, with the chemical formula FeCl2. The anhydrous compound has a relative molecular mass of approximately 126.75 g/mol and contains iron in the +2 oxidation state. In industrial purchasing, the CAS number should be checked together with the physical form, assay, moisture content, packaging, and intended application because anhydrous ferrous chloride is different from hydrated ferrous chloride products.
I use CAS 7758-94-3 as the starting point for product identification, not as a complete specification. Buyers should confirm whether they require dry anhydrous FeCl2, a hydrated grade, or an aqueous ferrous chloride solution. These forms can differ in concentration, handling behavior, transport classification, and suitability for water treatment, chemical processing, or manufacturing.
CAS 7758-94-3 is the Chemical Abstracts Service registry number associated with iron(II) chloride. Its formula is FeCl2, meaning that each formula unit contains one iron atom and two chlorine atoms. The theoretical iron content of anhydrous FeCl2 is approximately 44.1% by mass, calculated from an iron atomic mass of 55.845 and a formula mass of 126.75 g/mol.
Ferrous chloride is generally described as a pale green, yellow-green, or gray-green solid, although its appearance can change with purity, hydration, oxidation, and storage conditions. It is an inorganic chloride salt that is moisture-sensitive and can oxidize from iron(II) to iron(III) when exposed to air or other oxidizing conditions. For this reason, appearance alone should not be used to release a batch; buyers should rely on the certificate of analysis and agreed testing methods.
In water, ferrous chloride dissociates into iron(II) ions and chloride ions. The Fe2+ ion can participate in redox reactions and may be further oxidized to Fe3+. This chemical behavior explains why ferrous chloride is useful as an iron source and reducing or reactive intermediate in selected industrial processes, while also creating a need for controlled storage.
The material is not the same as ferric chloride, which contains iron in the +3 oxidation state and has the CAS number 7705-08-0. Ferrous chloride should also not be confused with ferrous chloride tetrahydrate, which is a hydrated form commonly identified by a different CAS number. When I prepare a quotation, I recommend confirming the exact CAS number, formula, hydration state, and concentration before commercial terms are finalized.
| Item | Reference information | Buying relevance |
|---|---|---|
| CAS number | 7758-94-3 | Confirms the chemical identity requested |
| Formula | FeCl2 | Distinguishes ferrous chloride from ferric chloride and hydrates |
| Relative molecular mass | Approximately 126.75 g/mol | Useful for stoichiometric calculations and formulation work |
| Theoretical iron content | Approximately 44.1 wt% in anhydrous FeCl2 | Helps evaluate material balance and dosing calculations |
These figures describe the chemical substance rather than a guaranteed commercial grade. Actual assay, water content, insoluble matter, oxidation state, and trace-metal levels must be confirmed against the supplier’s specification. If a process depends on iron concentration, I advise buyers to calculate dosage from the actual assay and supplied form instead of using the theoretical value alone.
Ferrous salts can be used as iron sources in water and wastewater treatment processes, particularly where iron-based coagulation, precipitation, or chemical reduction is part of the treatment design. The appropriate product form depends on the dosing equipment, required iron concentration, water chemistry, and site safety procedures. A buyer should not select ferrous chloride solely because the CAS number appears in a treatment formula; jar testing or process validation may be necessary.
Ferrous chloride can serve as a reagent, catalyst component, or intermediate in chemical manufacturing. Its suitability depends on the reaction pathway, tolerance for chloride ions, sensitivity to oxidation, and required impurity profile. For synthesis customers, I recommend requesting information about assay, insoluble residue, free acid or alkalinity where relevant, and trace elements that could affect downstream reactions.
Some industrial formulations use ferrous chloride as a soluble iron source or as a precursor for further conversion into other iron compounds. The material may also be selected when the process specifically requires iron in the +2 oxidation state. In these applications, controlling exposure to oxygen, moisture, and incompatible oxidizing materials is important because unwanted oxidation can change performance.
The first distinction is between anhydrous ferrous chloride and hydrated ferrous chloride. Anhydrous FeCl2 corresponds to CAS 7758-94-3, while hydrated materials contain a defined or variable amount of water and may be sold under another CAS number. Hydration changes the molecular mass, theoretical iron percentage, appearance, flow properties, and the amount of product required to achieve a target iron dose.
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The second distinction is physical form. Depending on the supply route, buyers may evaluate solid material, hydrated crystals, or an aqueous solution. A solution can simplify metering but introduces concentration, freezing, corrosion, packaging, and transport considerations. A solid can offer more concentrated active material by weight, but it may require controlled handling and suitable dissolution equipment.
A commercial inquiry should identify more than “CAS 7758-94-3.” At minimum, I suggest specifying the required assay, hydration state, iron(II) content, moisture or water content, insoluble matter, chloride content if relevant, appearance, packaging, and applicable test methods. If the product will enter a regulated or sensitive process, the buyer should also define limits for heavy metals and other trace impurities.
I recommend starting with the end-use specification and working backward to the product form. A water-treatment buyer may prioritize solution concentration, reliable delivery, and dosing compatibility, while a synthesis customer may prioritize low impurities, reproducible assay, and oxidation-state control. The same CAS number can therefore lead to different purchasing decisions for different industries.
Next, compare the supplier’s technical documents with your internal requirements. Check whether the stated specification identifies test methods, batch information, net weight, storage guidance, and shelf-life or retest information where applicable. If the supplier only provides a generic product name without clearly identifying the form and assay, I would treat that as a reason to request clarification before placing an order.
Price should be evaluated per unit of active FeCl2 or elemental iron, not only per kilogram of packaged material. Moisture, hydration, solution concentration, packaging, minimum order quantity, and destination logistics can materially change the delivered cost. Lead time can also vary according to production scheduling, export documentation, packaging availability, and the destination’s chemical import requirements.
Azeal Materials can support industrial inquiries by reviewing the requested CAS number, confirming the required product form, preparing a specification-based quotation, and discussing packaging and shipment arrangements. We can also provide product documentation such as a certificate of analysis and safety data sheet when applicable to the order. Final availability, specification, minimum order quantity, and lead time should be confirmed for each project rather than assumed from a general product description.
Ferrous chloride should be handled according to the current safety data sheet and the buyer’s site procedures. Because the material may be affected by moisture and oxidation, storage conditions should be selected to limit unnecessary exposure to air, water, heat, and incompatible chemicals. Containers should remain properly closed, clearly labeled, and suitable for the product’s corrosive or reactive characteristics.
Personnel should use a documented risk assessment to select protective equipment, ventilation, spill controls, and emergency measures. The correct transport classification and packaging requirements depend on the product form, concentration, jurisdiction, and current regulatory rules. I recommend that buyers verify these details with their compliance and logistics teams before shipment.
CAS 7758-94-3 is anhydrous ferrous chloride, an iron(II) chloride compound used as an industrial iron source, reagent, and process chemical. Its value depends on the application and on maintaining the required chemical form, assay, oxidation state, and impurity profile. The most reliable purchasing approach is to match the product specification to the process rather than buying by CAS number alone.
As a next step, send Azeal Materials your required quantity, application, target assay, physical form, packaging preference, destination, and documentation requirements. We can then help confirm whether anhydrous FeCl2 is appropriate or whether a hydrated or solution form should be evaluated. This specification-first approach helps reduce substitution risk and supports a more accurate technical and commercial quotation.
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