CAS 7758-94-3 is ferrous chloride tetrahydrate, also called iron(II) chloride tetrahydrate. Its chemical formula is FeCl2·4H2O, and its molecular weight is approximately 198.81 g/mol. I supply this material as an inorganic iron salt for applications that require soluble ferrous iron, chloride chemistry, or a reducing environment. Buyers should distinguish it from ferric chloride, because ferrous chloride contains iron in the +2 oxidation state while ferric chloride contains iron in the +3 state.
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Ferrous chloride tetrahydrate is the hydrated form of iron(II) chloride. The “tetrahydrate” designation means that four water molecules are incorporated into the crystal structure for each FeCl2 unit. This bound water affects the product’s molecular weight, appearance, storage behavior, and calculation of active material during formulation.
On a theoretical molecular-weight basis, FeCl2·4H2O contains approximately 28.1% iron, 35.7% chloride, and 36.2% crystallization water. These values are useful for stoichiometric planning, but a commercial specification should still be used for purchasing and process calculations. Actual assay, moisture, insoluble matter, and trace-metal limits depend on the agreed grade and analytical method.
| Property | Typical identification or planning value |
|---|---|
| CAS number | 7758-94-3 |
| Common name | Ferrous chloride tetrahydrate |
| Chemical formula | FeCl2·4H2O |
| Molecular weight | Approximately 198.81 g/mol |
| Theoretical iron content | Approximately 28.1% |
The primary function of ferrous chloride tetrahydrate is to provide soluble Fe2+ ions. In water treatment and industrial chemistry, these ions can participate in precipitation, reduction, complexation, and other reactions selected by the process designer. The material is therefore more than a source of chloride; its useful performance is mainly associated with the behavior of ferrous iron.
Ferrous ions can be oxidized by oxygen to ferric ions under suitable conditions. This oxidation may change solution color, reaction performance, and the effective iron valence available to a process. For that reason, I recommend that buyers evaluate exposure to air, moisture, heat, residence time, and incompatible chemicals before selecting packaging or defining a storage procedure.
Ferrous chloride is an iron(II) compound, whereas ferric chloride is an iron(III) compound. They are not interchangeable simply because both contain iron and chloride. Their oxidation state, reactivity, solution behavior, dosing requirements, and suitability for a particular treatment step may differ.
When a process specifically requires a reducing iron salt or ferrous iron, CAS 7758-94-3 may be the appropriate starting material. If the process requires ferric coagulation or oxidation-state-specific chemistry, ferric chloride may be more suitable. I advise buyers to confirm the required oxidation state with their process engineer before comparing quotations.
Ferrous chloride tetrahydrate may be used as an iron source in water and wastewater treatment processes. Depending on the treatment design, ferrous iron can support precipitation or reaction pathways involving sulfide, phosphate, metals, and other dissolved species. The actual result depends on water chemistry, pH, dosage, mixing, oxidation conditions, and the target contaminant.
It should not be assumed that the same dosage works across different plants. Jar testing, laboratory screening, or controlled plant trials are appropriate where treatment performance is critical. Buyers should also consider the chloride load introduced by the product and the characteristics of the resulting sludge.
In chemical manufacturing, CAS 7758-94-3 can serve as a soluble ferrous salt or reducing reagent where the process requires Fe2+. It may also be used as an intermediate or feedstock in reactions that produce other iron-containing compounds. The right grade depends on impurity controls, concentration requirements, reaction conditions, and downstream product specifications.
Research laboratories may use ferrous chloride tetrahydrate when a measured source of ferrous ions is required. Because the compound is hydrated, laboratory calculations should use the molecular weight of the tetrahydrate rather than anhydrous FeCl2. I recommend recording the exact product form on internal methods, purchase orders, and batch documentation to avoid substitution errors.
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The main distinction is between the tetrahydrate and other iron chloride forms, including anhydrous ferrous chloride and ferric chloride products. A buyer should confirm the CAS number, chemical formula, hydration state, physical form, and assay basis before approval. A product labeled only “iron chloride” does not provide enough identity information for a controlled industrial purchase.
Ferrous chloride tetrahydrate is commonly handled as a crystalline or granular solid, with color and particle characteristics influenced by purity, hydration, and exposure conditions. I do not recommend specifying color as the only acceptance criterion. A stronger purchasing specification combines identity, assay, moisture or water content, insoluble matter, relevant trace impurities, packaging, and documentation requirements.
For B2B sourcing, the certificate of analysis should be aligned with the intended application. Core items may include ferrous chloride assay, total iron, ferrous iron content, moisture, insoluble matter, and selected heavy-metal limits. If the material will enter a regulated process, the buyer should define the applicable regulatory and quality requirements before requesting a quotation.
Packaging is also a technical consideration because hydrated iron salts can be affected by moisture exchange and oxidation during storage. I recommend confirming the inner liner, outer packaging, net weight, pallet configuration, labeling, and transport conditions. The supplier should provide a current safety data sheet and handling information appropriate to the supplied grade.
First, identify whether the material is intended for wastewater treatment, chemical synthesis, laboratory use, or another application. Treatment-grade purchasing may prioritize consistent iron content and economic dosing, while synthesis or laboratory use may require tighter impurity controls. The lowest quoted price is not necessarily the lowest process cost if variable assay or excess insoluble matter increases consumption.
Because the tetrahydrate contains approximately 36.2% crystallization water by theoretical composition, dosing calculations must use the correct molecular form. Buyers should clarify whether quotations and specifications are based on product mass, FeCl2 content, total iron, or ferrous iron. This prevents differences between supplier comparisons and actual plant performance.
Ferrous chloride tetrahydrate should be handled according to its current SDS and site risk assessment. Avoid unnecessary contact with moisture, incompatible materials, and prolonged air exposure where oxidation could affect the process. Personnel should use suitable protective equipment, ventilation, spill controls, and corrosion-resistant equipment as determined by the application and local requirements.
At Azeal Materials, I focus on helping industrial buyers verify whether CAS 7758-94-3 fits their formulation and process requirements before shipment. I can support discussions around chemical identity, tetrahydrate form, intended application, assay basis, packaging, documentation, and order planning. Final availability, specifications, packaging, and lead time should be confirmed against the current quotation and product documentation.
For repeat purchasing, I recommend establishing an agreed specification before the first commercial order. This may include the CAS number, formula, assay requirements, impurity limits, packaging format, batch documentation, and inspection expectations. Clear specifications make supplier comparisons more reliable and help reduce avoidable quality disputes.
CAS 7758-94-3 is ferrous chloride tetrahydrate, a hydrated iron(II) salt selected when a process requires soluble ferrous iron. Its identity, hydration state, oxidation behavior, theoretical composition, and application chemistry all affect purchasing and use. The best way to determine suitability is to compare the product specification with the process requirement rather than relying on the chemical name alone.
As a next step, prepare your target application, required quantity, assay or impurity limits, packaging preference, destination, and documentation needs. Contact Azeal Materials with these details so I can help review the appropriate supply option for your project. A clear technical specification at the inquiry stage supports more accurate quotations and a smoother B2B procurement process.
Contact us to discuss your requirements of CAS 7758-94-3. Our experienced sales team can help you identify the options that best suit your needs.