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Ferrous Sulfate (FeSO4)- Structure, Properties, Uses

Aug 9, 2022

Ferrous Sulfate (FeSO4)

Iron(II) sulfate, sometimes referred to as ferrous sulfate, is a group of salts with the chemical formula FeSO4.xH2O. It was once known as copperas’ green vitriol. It was first employed in the textile industry as a fixative for dyes, darkening hide, and ink ingredients.

A bluish-green compound called iron(II) sulfate is used to make ink, dye, and medications, among other things. Melanterite FeSO4.7H2O (blue-green) and Rozenite FeSO4.4H2O are some of the most well-known types. However, these substances are frequently found as heptahydrate (x = 7).


Since this compound plays a significant role in our daily lives, it is important to understand what ferrous sulfate is in depth.

What is Ferrous Sulfate?

An iron salt with the chemical formula FeSO4 is ferrous sulfate. Green vitriol is the common name for the iron salt ferrous sulfate. Oral iron is known by the generic names ferrous gluconate, ferrous fumarate, and ferrous sulfate. The finest and least expensive form of iron supplementation is ferrous sulfate. 


It is created when the iron is added to a solution of copper sulfate; because iron is much more chemically reactive, it pushes the copper out and forms iron sulfate in its stead. An inorganic salt called ferrous sulfate is utilized to cure iron deficiency and iron insufficiency-induced anemia. After oral ingestion, ferrous (Fe+2) sulfate is more quickly taken up than ferric (+3) iron.

Structure of Ferrous Sulfate 

Various salts contain iron(II) sulfate or ferrous sulfate. The sulfate’s chemical composition is FeSO4.xH2O. The most prevalent salt form is hexahydrate. Iron deficiency is treated medically with hydrated salt. It may also be applied in a variety of industrial settings. A similar aqua complex results from the dissolution of the Iron(II) sulfates in water. The architecture of this aqua complex is octahedral.[Fe(H2O)6]2+ is the formula for the aqua complex. A magnetic field and a mild external magnetic field can weakly draw some substances; a phenomenon known as paramagnetism.


Ferron Sulfate Structure

Physical Properties of Ferrous Sulfate

The following are some noteworthy properties of ferrous sulfate:

  • The chemical formula of ferrous sulfate is FeSO4.
  • The molar mass of anhydrous ferrous sulfate is 151.91 g/mol, whereas the molar mass of heptahydrate ferrous sulfate is 278.02 g/mol.
  • The appearance or color of ferrous sulfate crystals varies depending on the salt form they are found in. :
    • Anhydrous – White crystals
    • Heptahydrate – Bluish-green crystals.
    • Monohydrate – Yellowish white crystals
  • Ferrous sulfate’s melting point lies between 56-64°C, and its boiling point is >300°C. 
  • It is soluble in water, while its solubility in alcohol is negligible. 

Chemical Properties of Ferrous Sulfate 

  • When ferrous sulfate dissolves in water, [Fe(H2O)6]2+, a metallic complex, is created. It is paramagnetic, almost colorless.
  • When heated, ferrous sulfate sheds its crystallization water before the green crystals change into a white dehydrated material. When heated more, the anhydrous solid emits white fumes of SO3 and SO2, leaving ferric oxide residue, which is reddish-brown in color. At over 680 °C (1,256 °F), ferrous sulfate starts to break down.

2 FeSO4 → Fe2O3 + SO2 + SO3

  • As a reducing reagent, ferrous sulfate functions similarly to many other ferrous salts. For example, it converts chlorine to chloride. 

FeSO4 +  Cl2 →  Fe2(SO4)3 +  FeCl3

Production of Ferrous Sulfate (FeSO4)

  • Metal sheets or bars are polished in sulphuric acid tanks prior to coating or glazing. It generates a sizable quantity of iron(II) sulfate as a result.


  • Another key contribution is the sulfate process that turns ilmenite into titanium dioxide.
  • Ferrous sulfate, which may also be manufactured commercially, is created when pyrite is oxidized.


  • By the displacement of metals that are less reactive than Fe from their salt solution, ferrous sulfate can be produced. 



Ferrous Sulfate Uses 

In most cases, ferrous sulfate is used in commerce as a base for other iron compounds. It serves as a reducing agent to convert chromate into the less dangerous Cr(III) product. In the textile business, ferrous sulfate is used for color fixation. Additionally, it is used as an ink supplier to darken the suede. 

Used in Medicine

A medication often used to treat and prevent iron deficiency anemia is ferrous sulfate 325 mg. Red blood cells, which carry oxygen throughout the body, are made better by the body with the aid of iron. Anemia can result from the iron supply becoming too low due to factors including loss of blood, childbirth, or consuming too little iron.


An initial dose of 60 mg of elemental iron, or 325 mg of ferrous sulfate, is often administered once or twice a day. Larger dosages are not absorbed and cause more side effects, particularly vomiting, constipation, and black stools. Each pill contains ferrous sulfate 325 mg or 65 milligrams of elemental iron. 

Taking iron at the prescribed amount or as a substitute won’t harm your liver. Severe toxicity and accidental or purposeful overdoses from large amounts of iron include rapid liver failure.

Used as a Dye

Iron gall ink, used from the Middle Ages until the late 18th century, was the most well-known ink created using ferrous sulfate. As a color modifier, ferrous sulfate darkens or “saddens” natural colors on protein or cellulose fibers. As a natural colorant for dark colors, it also improves lightfastness. The well-known black dye formulations from the 17th and 18th centuries heavily use tannin and iron. Based on the pigment it is coupled with, iron interacts with the tannin in several dyestuffs to produce hues varying from lime green to black. 

Ferrous sulfate may be another choice for the reducing agent in a conventional indigo fermentation vat, often known as the “Copperas” vat. This vat is especially suited for cellulose fibers, and copperas is an ancient name for iron. It can occasionally be used to deepen a solution to draw black lines on the printed cloth.

Used in Agriculture

A soil additive termed ferrous sulfate reduces the pH of very alkaline soils so crops can absorb nutrients. Iron is utilized to cure illnesses in agriculture like Iron chlorosis. It does not operate as rapidly as ferric EDTA but has a longer duration of action. It may be used to make a permanent storage container by combining it with compost and burying it in the earth.

Other Uses

  • Adding ferrous sulfate to the cooling water passing through the turbines will generate a layer of protection that is non-corrosive.
  • Ferrous sulfate precipitate metallic gold from auric chloride during the gold refining process (gold dissolved in solution with aqua regia).
  • Ferrous sulfate has been used for flocculation-based water purification to prevent the algal blooms of water bodies and the phosphate removal process in municipal and industrial sewage treatment facilities.
  • Useful for treating wood paneling on buildings in a conventional manner, either separately, after dissolving it in water, or as a component of water-based paint.
  • A helpful reagent for detecting mushrooms is green vitriol.
  • It functions well as the Fenton reagent’s iron catalyst ingredient. 


Ferrous sulfate is an iron salt with the chemical formula FeSO4. One of the various forms of the element iron is ferrous sulfate. The solid material looks like tiny crystals in its native condition. Because of the usual color of the crystals—yellow, brown, or bluish-green—ferrous sulfate is commonly referred to as “green vitriol.”

The majority of iron supplements come in either ferric or ferrous form. This is dependent on the iron atoms’ chemical composition. The body more easily absorbs iron in ferrous forms than in ferric forms. As a result, medical professionals frequently believe that ferrous forms, such as ferrous sulfate, are the best option for iron supplementation.

Frequently Asked Questions 

1. What is ferrous sulfate used for? 

Ferrous sulphate is a mineral that is required by the body. Ferrous sulphate is used to treat iron deficiency anaemia (a lack of red blood cells caused by having too little iron in the body). 

2. What are ferrous sulfate side effects?

Like all medications, ferrous sulfate has side effects as well. The following are the common ferrous sulfate side effects:  

  • Constipation
  • Stomach pain
  • Nausea
  • Loss of appetite
  • Black-colored stools

Severe ferrous sulfate side effects include: 

  • Severe stomach pain
  • Bloody stools
  • Vomiting
  • Fever
  • Cough with bloody mucus

3. What is ferrous sulfate, and what are its advantages?

Myoglobin permits oxygen to be stored in muscle cells. Ferrous sulfate is a mineral that the body requires. Iron deficiency anemia, caused by a shortage of red blood cells in the body, can be treated with ferrous sulfate. It can also be used for purposes other than those stated above.

4. What distinguishes ferrous from ferric primarily?

There are several valencies for iron. It can either be ferric or ferrous, depending on how many electrons it loses. An iron atom acquires a +3 charge and becomes a ferric ion (Fe+3) when it loses three electrons. An iron atom gains a +2 charge and becomes a ferrous ion (Fe+2) when it loses two electrons. Ferrous ions have the electrical structure 3s2 3p6 3d6, while ferric ions have 3s2 3p6 3d5. Ferric ions are much more stable than ferrous ions as they are half-filled. FeO is an occurrence of a ferrous ion. FeCl3 is an example of a ferric ion.

Ferrous Sulfate


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