Dhristi JEE 2022-24

What is Ferrous Sulfate?

Ferrous sulfate, also known as Iron(II) sulfate represents a spectrum of salts having the formula of FeSO4.xH2O. Earlier, it was also known as the green vitriol of copperas. It was formerly used as a fixative for dyes in textile industries, blackening hide and as a component in ink. Approximately 7 centuries ago, the process of preparing sulfuric acid included the distillation of ferrous sulfate. 

Iron(II) sulfate is a bluish-green chemical that is employed in several applications like manufacturing ink, dye, and medicines. Some popularly known mineral forms of ferrous sulfate are Melanterite FeSO4·7H2O (blue-green), Rozenite FeSO4·4H2O (white, maybe a dehydrated version of melanterite).

Some of its mineral forms that are moderately rare are Ferrohexahydrite (FeSO4·6H2O), Siderotil (FeSO4·5H2O), Szomolnokite (FeSO4·H2O).

You should know about ferrous sulfate in detail because this chemical compound has a lot of importance in our day to day life. To know the concepts related to ferrous sulfate, you can simply give a read to this article. In this article, you will study the meaning of ferrous sulfate, its chemical name, its other names and how it is defined in chemistry. This chemical compound has a lot of properties and all those properties have been discussed in this article. In your daily life, you might be using ferrous sulfate in different ways so to know various other uses of this chemical, you can go through this article. Not only this, if you are preparing for any exam and want to have a stronghold on this topic, this article will help you with that. You will easily be able to answer all the questions asked in any competitive exam, in case these questions are related to ferrous sulfate. 

Ferrous Sulfate Structure – FeSO4

Iron(II) Sulfate or Ferrous sulfate denotes a range of salt. The formula for salt is FeSO4.xH2O. Heptahydrates are the most common form of salt. Hydrated salt is used medically for treating iron deficiency. It can also be used for various industrial applications as well. The Iron(II) sulfates dissolve in water to give the same aqua complex. This aqua complex has octahedral geometry. The formula of the aqua complex is [Fe(H2O)6]2+. It is paramagnetic. 

Physical Properties of Ferrous Sulfate- FeSO4

Chemical formula- FeSO4

Molar Mass

  • Anhydrous ferrous sulfate- 151.91 g/mol

  • Monohydrate ferrous sulfate- 169.93 g/mol

  • Pentahydrate ferrous sulfate- 241.99 g/mol

  • Hexahydrate ferrous sulfate- 260.00 g/mol

  • Heptahydrate ferrous sulfate- 278.02 g/mol


  • Anhydrous- White crystals

  • Monohydrate- Yellowish white crystals

  • Heptahydrate- Bluish-green crystals.

  • Melting point- 56-64°C

  • Boiling point- >300°C

  • Solubility in alcohol- Negligible

Solubility in Water

  • Monohydrate- 44.69 g/100mol at 77°C

  • Heptahydrate- 15.65 g/100mol at 0°C, 20.5 g/100mol at 10°C.

Refractive Index

  • Monohydrate- 1.591

  • Tetra hydrates 1.526-1.528

  • Pentahydrate- 1.513-1.515

  • Hexahydrate- 1.468

  • Heptahydrate- 1.471

Ferrous Sulfate Production

Sulphuric acid pickling baths are used to polish steel sheets or rods before plating or coating. As a by-product, it produces a substantial amount of iron(II) sulfate.


The sulfate process, which produces titanium dioxide from ilmenite, is another source of huge quantities.

The oxidation of pyrite produces ferrous sulfate, which is also economically produced: 2FeS2+7O2+2H2O⟶2FeSO4+2H2SO4

Ferrous sulfate can be made by removing metals that are less reactive than iron from their sulfate solutions: CuSO4+Fe⟶FeSO4+Cu


If ferrous sulfate is dissolved in water, it forms the metal aquo complex [Fe(H2O)6]2+ It is a nearly colorless and paramagnetic ion.

On heating, ferrous sulfate initially loses its water of crystallization, then the actual green crystals are transformed into an anhydrous solid of white-color. If it is further heated, then the anhydrous solid discharges white fumes of sulfur trioxide and sulfur dioxide leaving behind reddish-brown coloured ferric oxide. Ferrous sulfate begins to decompose at nearly 680 °C (1,256 °F).

2 FeSO4 → Fe2O3 + SO2 + SO3

Like all other ferrous salts, ferrous sulfate is a reducing agent. For instance, it reduces nitric acid to nitrogen monoxide and chlorine to chloride:

FeSO4 +  HNO3   H2SO4 →  Fe2(SO4)3 +  H2O +  NO

FeSO4 +  Cl2 →  Fe2(SO4)3 +  FeCl3


Ferrous sulfate is mostly used in industry as a precursor to other iron compounds. It's a reducing agent that's also used to turn chromate in cement into a less harmful Cr(III) compound. For centuries, ferrous sulfate has been used as a color fixative in the textile industry. Also used to blacken the leather and as an ink source. For more than 700 years, the distillation of green vitriol (Iron(II) sulfate) has been used to produce sulphuric acid.

Uses in Medicine

Iron is a required heavy element present in many multivitamin and mineral supplements. It's also used medically to treat or prevent iron deficiency anemia at greater doses. Iron will not affect your liver if you take it on recommended level or as a replacement dosage. Large doses of iron produce severe toxicity and incidental or intentional overdosages, one of which is abrupt liver failure.


Inks were made with ferrous sulfate, the most famous of which was iron gall ink, which was used from the Middle Ages until the end of the eighteenth century. The Lachish letters (c.588–586 BCE) were subjected to chemical analyses, which revealed the presence of iron. Furthermore, oak galls and copperas are likely to have been employed in the ink on those letters. Ferrous sulfate is also used as a mordant in wool dyeing. Furthermore, ferrous sulfate is used to make harewood, a material utilized in marquetry and parquetry since the 17th century.

Plant Development

Iron (II) sulfate, often known as ferrous sulfate, is a soil amendment that lowers the pH of high alkaline soils, allowing plants to absorb nutrients. To treat diseases in horticulture like Iron chlorosis, you can use iron. It doesn't work as quickly as ferric EDTA, but its effects last longer. It can be mixed with compost and buried in the ground to create a long-term storage container.

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FAQs (Frequently Asked Questions)

1.  What are the different properties of ferrous sulfate?

Ferrous sulfate is also known as Iron (II) sulfate or green vitriol is odorless and appears in blue-green crystals or powder. It has a density of 2.84 g/cm3 and a molecular weight of 151.908 g/mol. Its melting point and boiling points are 300 °C and 56-64 °C respectively. It is highly soluble in water and reacts with a lot of other chemicals. It reacts with aluminum to form aluminum sulfate and metallic iron and reacts with potassium permanganate to form ferric sulfate, manganese sulfate, potassium sulfate, and water. 

2.  How useful is ferrous sulfate and where can it be used?

Ferrous sulfate turns out to be a very useful chemical as it is used in a lot of ways such as it is used as Iron supplements for iron-deficient patients. It is also used in the treatment of anemia which is caused due to the deficiency of iron. Ferrous sulfate can also be used in the treatment with chlorine which is known as chlorinated copperas treatment. 

3.  Are questions related to ferrous sulfate asked in NEET exams?

Ferrous sulfate is an important chemical, therefore students need to be aware of it. A lot of questions related to this topic have been asked in many competitive exams including NEET. There's a high chance that in upcoming exams, questions can be asked related to the ferrous sulfate. So, you should prepare this topic thoroughly so that you can answer those questions easily. 

4. What are the benefits of ferrous sulfate? How are ferrous metals advantageous?

Ferrous sulfate has a major role to play in the biological world. This mineral plays a vital role in our body. It is used to treat and prevent anaemia that is caused due to iron deficiency, meaning a shortage of RBCs (red blood corpuscles) that is, lack of iron in the body.

Ferrous sulfate is lighter yet has powerful tensile strength. Some of the benefits of ferrous sulfate are high current conductivity (found in copper), zinc that is resistant to corrosion, and tolerance to magnetic force. These ferrous metals are modified into either intermediate metals or finished products.

5. What is the main difference between ferrous and ferric?

Iron can have numerous valencies. It is determined as ferric or ferrous depending on the number of electrons it loses. When an iron atom loses 3 electrons, it obtains a +3 charge and serves as a ferric ion (Fe+3). When an iron atom loses 2 electrons, it obtains a +2 charge and serves as a ferrous ion (Fe+2). The electronic configuration ferrous ion is 3s2 3p6 3d6 and the electronic configuration of ferric ion is 3s2 3p6 3d5. According to Hund's rule of multiplicity, ferric ions are more stable than ferrous ions because it is half-filled. Example of ferrous compounds: FeO. Example of ferric compounds: FeCl3.