What is ferric chloride?

Ferric chloride (FeCl₃, iron(III) chloride) is an iron salt supplied for water treatment as a dark brown liquid at about 40% w/w. Dosed into raw water or wastewater it hydrolyses to iron(III) hydroxide flocs that bind suspended solids, colour and phosphorus so they settle out. Our ferric chloride is listed under NSF/ANSI/CAN 60 (listing C0237336), the drinking-water treatment chemical standard, and is REACH-registered. The grade is CHIMIFLOC FR 4014.

What is FeCl3 and what is its chemical name?

FeCl3 is ferric chloride. Its chemical name is iron(III) chloride, and it is also called iron trichloride. The formula, normally written FeCl₃, means one iron atom in the +3 oxidation state combined with three chlorine atoms. It is an iron salt, best known as a coagulant for treating drinking water and wastewater.

What is the formula of ferric chloride?

Ferric chloride is FeCl₃ — one iron atom in the +3 oxidation state bonded to three chlorine atoms. It is also written as iron(III) chloride. Ferrous chloride is FeCl₂, iron in the +2 state. The molar mass of FeCl₃ is 162.20 g/mol.

What is the name of FeCl2 and FeCl3?

FeCl₂ is iron(II) chloride, also called ferrous chloride; FeCl₃ is iron(III) chloride, also called ferric chloride. The Roman numeral gives the oxidation state of the iron. In the older naming, still common in industry, the ending -ous marks the lower state (+2) and the ending -ic the higher state (+3).

Is ferric chloride an acid or a salt?

Ferric chloride, or iron(III) chloride, is a salt and not an acid: it is the iron(III) salt of hydrochloric acid. Its solution in water is nevertheless strongly acidic, because the dissolved iron(III) ion reacts with water and releases hydrogen ions. Chemists also class anhydrous FeCl₃ as a Lewis acid, which is why it serves as a catalyst.

What colour is ferric chloride (FeCl3)?

Ferric chloride solutions can range from yellow-brown to dark brown. Colour alone does not establish concentration, purity or treatment performance. Check the agreed specification and batch analysis, and refer an unexpected appearance to the supplier before use. As a solid, anhydrous ferric chloride is dark brown to black and the hexahydrate crystals are brownish-yellow to orange.

What colour is ferrous chloride (FeCl2)?

Ferrous chloride (FeCl₂) is white to pale green as a dry solid, and its hydrated crystals and solutions are pale green. That sets it apart from ferric chloride (FeCl₃), which is dark brown to black as a solid and yellow-brown to dark brown in solution. In air ferrous chloride slowly oxidises towards the ferric form, so colour alone is not a reliable identity test.

Is ferric chloride (FeCl3) soluble in water?

Yes, highly soluble. It dissolves readily and the resulting solution is strongly acidic because FeCl₃ hydrolyses in water. A typical handbook value is about 92 g per 100 mL of water at 20 °C. It also dissolves in alcohols and acetone.

Does ferric chloride form a precipitate?

FeCl₃ itself dissolves rather than precipitating. What precipitates is iron(III) hydroxide, Fe(OH)₃ — the brown floc formed when FeCl₃ hydrolyses. That precipitate is precisely the mechanism that makes it useful as a coagulant. It appears once the acidity of the solution is taken up, for example by the alkalinity of the water being treated.

What does iron form when it reacts with chlorine?

Iron reacts with chlorine gas to form iron(III) chloride, FeCl₃: 2Fe + 3Cl₂ → 2FeCl₃. Chlorine is a strong enough oxidising agent to take iron to the +3 state, so the product is ferric chloride, not ferrous chloride. Ferrous chloride (FeCl₂) forms instead when iron dissolves in hydrochloric acid.

What is iron(III) hydroxide and why does it form?

Iron(III) hydroxide, Fe(OH)₃, also called ferric hydroxide, is the brown solid, barely soluble in water, that appears when an iron(III) salt meets water or an alkali. It forms because the iron(III) ion binds hydroxide so strongly that it takes it from the water itself. In water treatment this precipitate is the floc that traps suspended particles.

What is ferric chloride used for?

Mainly as a coagulant in drinking water and wastewater treatment, removing suspended solids, phosphorus and turbidity, and conditioning sludge. It is also used in etching and metal surface treatment. Smaller uses include catalysis in chemical manufacturing and the dyeing of textiles.

Is iron chloride FeCl2 or FeCl3?

Both exist. FeCl₃ is ferric chloride, iron in the +3 state, and is the grade used for water treatment coagulation. FeCl₂ is ferrous chloride, +2. Different products, different applications, not interchangeable. Textbooks and suppliers may call either one iron chloride, so check the formula.

Why use FeCl3 in water treatment?

It hydrolyses to iron hydroxide flocs that bind fine particles into settleable aggregates, works across a wide pH range, removes phosphorus, and improves sludge dewatering. It is also effective in cold water, and the right dose is found by jar testing.

What is the difference between ferric chloride and ferrous chloride?

The difference is the oxidation state of the iron: +3 in ferric chloride (FeCl₃) and +2 in ferrous chloride (FeCl₂). Ferric chloride is one of the most widely used coagulants for water and wastewater treatment. Ferrous chloride is used mainly for sulphide and odour control and for specific refinery and oilfield duties; the two products are not interchangeable.

What is ferric chloride 40%?

Ferric chloride 40% is the usual commercial liquid grade: a solution of about 40% FeCl₃ by weight in water. It is the form in which ferric chloride is most often supplied for water treatment, a dark brown liquid ready for dosing. Our 40% ± 1% grade is CHIMIFLOC FR 4014.

Is ferric chloride toxic to humans?

Ferric chloride 40% solution, the grade used in water treatment, is classified as harmful if swallowed. It causes serious eye damage and skin irritation, and it may be corrosive to metals; its signal word is "Danger" under the GHS classification. It is not classified for carcinogenicity, germ cell mutagenicity, reproductive toxicity or sensitisation; the safety data sheet records no data for these. Wear protective gloves, protective clothing and eye or face protection. In the eyes: rinse at once with plenty of water for at least 15 minutes and get medical attention immediately. If swallowed: rinse the mouth, do not induce vomiting and get medical attention immediately. Full first-aid, handling and storage measures are in the safety data sheet.

Ferric Chloride (FeCl₃)

Ferric chloride (FeCl₃, also written FeCl3), also called iron(III) chloride, is one of the most widely used coagulants in municipal and industrial water treatment. It is supplied most often as a dark brown aqueous solution, and it works by destabilising the fine suspended particles that will not settle out of water on their own.

This page explains what ferric chloride is, how it behaves in treatment, the grades it is supplied in, and what to consider when buying it. For our own product specification, see CHIMIFLOC FR 4014.

FeCl₃ properties: name, formula, appearance, solubility

Ferric chloride is the iron(III) salt of hydrochloric acid, formula FeCl₃. It is sold as a dark anhydrous solid, as yellow-brown hexahydrate crystals and, most often, as a brown aqueous solution of about 40% by weight. The table lists its identifiers and typical handbook values. The source of each value is given under References.

Key facts about ferric chloride (FeCl3)
Property	Value
Chemical name of FeCl₃	Iron(III) chloride. Common name: ferric chloride. Also called iron trichloride.
Formula	FeCl₃ (also written FeCl3)
CAS number	7705-08-0 (anhydrous)10025-77-1 (hexahydrate)
Molecular weight (molar mass)	162.20 g/mol (anhydrous FeCl₃)270.29 g/mol (hexahydrate, FeCl₃·6H₂O)
Commercial forms	Anhydrous solidHexahydrate crystals (FeCl₃·6H₂O)Aqueous solution, commonly about 40% w/w
Appearance	Anhydrous: dark brown to black crystals, green by reflected lightHexahydrate: brownish-yellow to orange crystalsAqueous solution: yellow-brown to dark brown liquid
Solubility in water	Very soluble: about 92 g per 100 mL of water at 20 °C (typical handbook value). It hydrolyses as it dissolves.
pH of FeCl₃ solution	Strongly acidic; the value depends on concentration and grade. Our 40% grade is specified at pH below 1.0 (1% solution).

Looking for the commercial product? See ferric chloride 40% (CHIMIFLOC FR 4014).

What ferric chloride is

Ferric chloride is an iron salt in which iron carries a +3 charge. It is distinct from ferrous chloride (FeCl₂), where iron carries a +2 charge — the two are different products with different uses and are not interchangeable. Ferric chloride is strongly acidic in solution and highly soluble in water.

The name describes the chemistry. “Ferric” is the older word for iron in the +3 oxidation state, so ferric chloride and iron(III) chloride are the same compound. Because each iron atom is combined with three chlorides, it is also called iron trichloride. Textbooks and suppliers often shorten the name to iron chloride, which is why the formula is stated when ordering, to avoid confusion with iron(II) chloride.

Ferric chloride vs ferrous chloride (FeCl₃ vs FeCl₂)

Ferric chloride (FeCl₃) and ferrous chloride (FeCl₂) are two different iron chlorides. Iron is in the +3 oxidation state in the first and +2 in the second. That difference changes the formula, the colour and the main use. The colour of iron chloride depends on which it is: iron(III) chloride is yellow-brown to dark brown, iron(II) chloride is pale green.

Ferric chloride and ferrous chloride compared
Property	Ferric chloride	Ferrous chloride
Systematic name	Iron(III) chloride	Iron(II) chloride
Formula	FeCl₃	FeCl₂ (also written FeCl2)
Iron oxidation state	+3	+2
Molar mass	162.20 g/mol	126.75 g/mol
CAS number	7705-08-0	7758-94-3
Typical colour	Dark brown to black solid; yellow-brown to dark brown in solution	White to pale green solid; greenish in solution
Main use	Coagulant for drinking water and wastewater; phosphorus removal; etching	Hydrogen sulphide (H₂S) and odour control; wastewater treatment; reducing agent

For the iron(II) product, see ferrous chloride (FeCl₂) solution.

Ferric vs ferrous chloride: the full comparison

How ferric chloride is made and what it does in water

Ferric chloride forms when iron reacts with chlorine: the chlorine oxidises the iron to the +3 state. In water the iron(III) ion reacts with the water itself (hydrolysis). Iron(III) hydroxide, Fe(OH)₃, forms and acid is released, which is why solutions of ferric chloride are strongly acidic.

Iron with chlorine
2Fe + 3Cl₂ → 2FeCl₃
Hot iron reacts with chlorine gas to give iron(III) chloride. This is the textbook equation. Industrial routes vary: producers may chlorinate scrap iron directly or chlorinate a ferrous chloride solution.
Hydrolysis in water
FeCl₃ + 3H₂O ⇌ Fe(OH)₃ + 3HCl
A simplified overall equation. In practice the iron passes through several intermediate hydroxide species before iron(III) hydroxide precipitates.
In natural water that holds alkalinity
FeCl₃ + 3HCO₃^- → Fe(OH)₃ + 3CO₂ + 3Cl^-
In treatment the acid is taken up by the bicarbonate alkalinity of the water. This is why ferric chloride consumes alkalinity and lowers the pH.

Iron(III) hydroxide, also called ferric hydroxide, is a brown to reddish-brown solid that barely dissolves in water. It is the material of the brown floc seen in a treatment plant.

How it works as a coagulant

When ferric chloride is dosed into water, it hydrolyses and forms iron hydroxide. Three things follow:

Charge neutralisation. Most suspended particles carry a negative surface charge that keeps them apart. The positively charged iron species neutralise it so particles can approach each other.
Floc formation. Iron hydroxide precipitates and sweeps fine particles into larger aggregates (flocs) heavy enough to settle or be filtered.
Phosphorus removal. Iron binds phosphate into an insoluble form, removing it from the water.

Ferric chloride works across a relatively wide pH band and is effective in cold water, which is why it is often chosen over alternatives. It consumes alkalinity, so pH correction is a normal part of dosing design.

For the general mechanism, read how coagulation and flocculation work in water treatment.

Uses of ferric chloride: where it is used

Ferric chloride is used mainly as a coagulant in drinking water and wastewater treatment, where it removes suspended solids, colour and phosphorus and conditions sludge. Outside water treatment it is an etchant for copper and other metals and a reagent in chemical manufacturing. The main uses are listed below.

Drinking water treatment — turbidity, colour and organic-matter removal. Added at the rapid mix, it forms flocs that carry fine particles out in clarification and filtration.Coagulants for municipal water treatment
Municipal wastewater — primary treatment, phosphorus removal, sludge conditioning ahead of dewatering. It can be dosed ahead of primary settling or into the biological stage.Water treatment solutions
Phosphorus removal — iron binds dissolved phosphate into an insoluble iron phosphate that leaves with the sludge. The dose is worked out from the phosphorus load, not from a fixed figure.Phosphorus removal with ferric chloride: dosing guide
Sludge conditioning and dewatering — improves the water release of sludge on belt presses and centrifuges.
Industrial effluent — solids and metals removal across food, textile and process industries.Coagulants for industrial wastewater
Odour and sulphide control — iron binds dissolved sulphide, which suppresses hydrogen sulphide (H₂S) odour in wastewater. Ferrous chloride is also used for this duty.Ferrous chloride (FeCl₂) solution
Industrial etching and metal surface treatment — a separate, non-water-treatment use. Ferric chloride solution is a well-known etchant for copper on printed circuit boards and for engraving and photo-etching metals.Surface treatment chemicals
Other chemical uses — a catalyst in organic synthesis (Friedel-Crafts reactions), a mordant in textile dyeing, and a starting material for pigments and other iron salts.

Ferric chloride vs alum and PAC

No coagulant is best for every water. Ferric chloride tends to lead on phosphorus removal, on water high in colour or organic matter, and in cold water, and it works across a wide pH band. Polyaluminium chloride (PAC) is partly neutralised when it is made, so it consumes less alkalinity and typically makes less sludge, which suits low-alkalinity water. Alum (aluminium sulfate) is the classical aluminium coagulant and performs well on easy, well-buffered surface water, within a narrower pH window. Iron flocs are typically denser than aluminium flocs. The sound way to choose is a jar test on the actual water.

Full comparison: ferric chloride vs PAC vs alum

Ferric chloride dosing in brief

There is no single correct dose of ferric chloride. The dose depends on the water: its turbidity, pH, alkalinity, temperature and the removal target. It is set by jar tests on the actual water and then trimmed in the plant. For phosphorus removal the dose is worked out from the phosphorus load, as a ratio of iron to phosphorus. Because ferric chloride consumes alkalinity, pH correction is part of the dosing design.

Grades, concentration and supply

When comparing ferric chloride offers, confirm the concentration basis, agreed limits and delivered quantity. Price per litre alone does not establish which offer supplies the required amount of product.

Buyer's checklist for ferric chloride 40% solution: concentration basis, COA, listing, packaging and RFQ

ferric chloride export supplier

Required application and agreed product specification.
Concentration basis and batch certificate of analysis.
Required documentation and any application-specific approvals.
Quantity, delivery destination, packaging and unloading arrangements.

For CHIMIFLOC FR 4014, compare the product technical sheet with your required specification. Include the application and documentation requirements when requesting a quotation.

Ferric chloride: formula, colour and solubility

What is ferric chloride?: Ferric chloride (FeCl₃, iron(III) chloride) is an iron salt supplied for water treatment as a dark brown liquid at about 40% w/w. Dosed into raw water or wastewater it hydrolyses to iron(III) hydroxide flocs that bind suspended solids, colour and phosphorus so they settle out. Our ferric chloride is listed under NSF/ANSI/CAN 60 (listing C0237336), the drinking-water treatment chemical standard, and is REACH-registered. The grade is CHIMIFLOC FR 4014.
What is FeCl3 and what is its chemical name?: FeCl3 is ferric chloride. Its chemical name is iron(III) chloride, and it is also called iron trichloride. The formula, normally written FeCl₃, means one iron atom in the +3 oxidation state combined with three chlorine atoms. It is an iron salt, best known as a coagulant for treating drinking water and wastewater.
What is the formula of ferric chloride?: Ferric chloride is FeCl₃ — one iron atom in the +3 oxidation state bonded to three chlorine atoms. It is also written as iron(III) chloride. Ferrous chloride is FeCl₂, iron in the +2 state. The molar mass of FeCl₃ is 162.20 g/mol.
What is the name of FeCl2 and FeCl3?: FeCl₂ is iron(II) chloride, also called ferrous chloride; FeCl₃ is iron(III) chloride, also called ferric chloride. The Roman numeral gives the oxidation state of the iron. In the older naming, still common in industry, the ending -ous marks the lower state (+2) and the ending -ic the higher state (+3).
Is ferric chloride an acid or a salt?: Ferric chloride, or iron(III) chloride, is a salt and not an acid: it is the iron(III) salt of hydrochloric acid. Its solution in water is nevertheless strongly acidic, because the dissolved iron(III) ion reacts with water and releases hydrogen ions. Chemists also class anhydrous FeCl₃ as a Lewis acid, which is why it serves as a catalyst.
What colour is ferric chloride (FeCl3)?: Ferric chloride solutions can range from yellow-brown to dark brown. Colour alone does not establish concentration, purity or treatment performance. Check the agreed specification and batch analysis, and refer an unexpected appearance to the supplier before use. As a solid, anhydrous ferric chloride is dark brown to black and the hexahydrate crystals are brownish-yellow to orange.
What colour is ferrous chloride (FeCl2)?: Ferrous chloride (FeCl₂) is white to pale green as a dry solid, and its hydrated crystals and solutions are pale green. That sets it apart from ferric chloride (FeCl₃), which is dark brown to black as a solid and yellow-brown to dark brown in solution. In air ferrous chloride slowly oxidises towards the ferric form, so colour alone is not a reliable identity test.
Is ferric chloride (FeCl3) soluble in water?: Yes, highly soluble. It dissolves readily and the resulting solution is strongly acidic because FeCl₃ hydrolyses in water. A typical handbook value is about 92 g per 100 mL of water at 20 °C. It also dissolves in alcohols and acetone.
Does ferric chloride form a precipitate?: FeCl₃ itself dissolves rather than precipitating. What precipitates is iron(III) hydroxide, Fe(OH)₃ — the brown floc formed when FeCl₃ hydrolyses. That precipitate is precisely the mechanism that makes it useful as a coagulant. It appears once the acidity of the solution is taken up, for example by the alkalinity of the water being treated.
What does iron form when it reacts with chlorine?: Iron reacts with chlorine gas to form iron(III) chloride, FeCl₃: 2Fe + 3Cl₂ → 2FeCl₃. Chlorine is a strong enough oxidising agent to take iron to the +3 state, so the product is ferric chloride, not ferrous chloride. Ferrous chloride (FeCl₂) forms instead when iron dissolves in hydrochloric acid.
What is iron(III) hydroxide and why does it form?: Iron(III) hydroxide, Fe(OH)₃, also called ferric hydroxide, is the brown solid, barely soluble in water, that appears when an iron(III) salt meets water or an alkali. It forms because the iron(III) ion binds hydroxide so strongly that it takes it from the water itself. In water treatment this precipitate is the floc that traps suspended particles.

Frequently asked questions

What is ferric chloride used for?: Mainly as a coagulant in drinking water and wastewater treatment, removing suspended solids, phosphorus and turbidity, and conditioning sludge. It is also used in etching and metal surface treatment. Smaller uses include catalysis in chemical manufacturing and the dyeing of textiles.
Is iron chloride FeCl2 or FeCl3?: Both exist. FeCl₃ is ferric chloride, iron in the +3 state, and is the grade used for water treatment coagulation. FeCl₂ is ferrous chloride, +2. Different products, different applications, not interchangeable. Textbooks and suppliers may call either one iron chloride, so check the formula.
Why use FeCl3 in water treatment?: It hydrolyses to iron hydroxide flocs that bind fine particles into settleable aggregates, works across a wide pH range, removes phosphorus, and improves sludge dewatering. It is also effective in cold water, and the right dose is found by jar testing.
What is the difference between ferric chloride and ferrous chloride?: The difference is the oxidation state of the iron: +3 in ferric chloride (FeCl₃) and +2 in ferrous chloride (FeCl₂). Ferric chloride is one of the most widely used coagulants for water and wastewater treatment. Ferrous chloride is used mainly for sulphide and odour control and for specific refinery and oilfield duties; the two products are not interchangeable.
What is ferric chloride 40%?: Ferric chloride 40% is the usual commercial liquid grade: a solution of about 40% FeCl₃ by weight in water. It is the form in which ferric chloride is most often supplied for water treatment, a dark brown liquid ready for dosing. Our 40% ± 1% grade is CHIMIFLOC FR 4014.
Is ferric chloride toxic to humans?: Ferric chloride 40% solution, the grade used in water treatment, is classified as harmful if swallowed. It causes serious eye damage and skin irritation, and it may be corrosive to metals; its signal word is "Danger" under the GHS classification. It is not classified for carcinogenicity, germ cell mutagenicity, reproductive toxicity or sensitisation; the safety data sheet records no data for these. Wear protective gloves, protective clothing and eye or face protection. In the eyes: rinse at once with plenty of water for at least 15 minutes and get medical attention immediately. If swallowed: rinse the mouth, do not induce vomiting and get medical attention immediately. Full first-aid, handling and storage measures are in the safety data sheet.

Our ferric chloride

CHIMI ART has been an Egyptian chemical manufacturer since 1977. Our liquid grade is CHIMIFLOC FR 4014, a 40% ± 1% solution.

Send the application, quantity, destination and required specification with your enquiry. Use the product page to obtain the technical sheet and request safety documentation.

The safety data sheet (SDS, also called MSDS) for ferric chloride (FeCl3) is available on request from the product page.

Ferric chloride 40% (CHIMIFLOC FR 4014): specification and quote

References

PubChem CID 24380Iron chloride (FeCl3): names, formula, CAS number, molecular weight, appearance, solubility, pH, manufacture and uses (U.S. National Library of Medicine)
PubChem CID 6093258Ferric chloride hexahydrate: CAS number, molecular weight and appearance
PubChem CID 24458Ferrous chloride (FeCl2): formula, CAS number, molecular weight, colour, manufacture and uses
PubChem CID 16211588Ferrous chloride tetrahydrate: colour of the hydrated crystals
NIST Chemistry WebBookIron trichloride: formula, molecular weight and CAS registry number (U.S. National Institute of Standards and Technology)
OpenStax Chemistry 2e, 2.7Chemical nomenclature: iron(II) chloride and iron(III) chloride, ferrous and ferric (Rice University)
OpenStax Chemistry 2e, 11.5Colloids: iron(III) hydroxide from iron(III) chloride and water
OpenStax Chemistry 2e, 14.4Hydrolysis of salts: why the hydrated iron(III) ion makes a solution acidic
LibreTexts ChemistryMore reactions of halogens: iron with chlorine gives iron(III) chloride
TU Delft OpenCourseWareDrinking water treatment, coagulation and flocculation: iron chloride, iron hydroxide flocs, pH and the jar test
NPTEL, Lecture 9Coagulation and flocculation: reaction of ferric chloride with alkalinity, and the jar test (Indian Institutes of Technology)

The identifiers, values and equations on this page were checked against these sources on 6 October 2026.

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Ferric Chloride (FeCl3)

FeCl3 properties: name, formula, appearance, solubility