Chemical Bonding and Molecular Structure

Ferrous Sulphate

Iron(II) sulfate or ferrous sulfate signifies a variety of salts with the formula \({FeSO_4 \cdot xH_2O}\). These compounds are most commonly known as heptahydrate (x = 7) but are also known for several x values. Hydrated form is medically used for the treatment of iron deficiency, as well as for industrial applications. It is well known since ancient times as copperas and green vitriol (vitriol is an archaic term for the sulfate), blue-green heptahydrate (hydrate with “7” water molecules) is the most common type of this material. Learn ferrous sulphate in this article.

Ferrous Sulphate

                                                                                                      Ferrous Sulphate

What is Ferrous Sulphate?

Ferrous sulfate is an iron salt that is also known as green vitriol. Ferrous Sulfate signifies a variety of salts with the formula \({FeSO_4 \cdot xH_2O}\). The Other names of Iron(II) sulphate include; Ferrous sulfate, Green vitriol, Iron vitriol, Copperas, Melanterite, Szomolnokite. Blue-green heptahydrate (hydrate with “7” water molecules) is the most common type of this material. All Iron(II) sulfates dissolve in water to produce the same aquo complex \({[Fe(H_2O)_6]^{2+}}\), which is paramagnetic and has the octahedral molecular geometry.

The term copperas goes back to the time period when copper(II) sulfate was known as blue copperas, and perhaps, by contrast, iron(II) and zinc sulfate were known as green and white copperas. It forms when iron filings mix into a copper sulfate solution, iron pushes the copper because it is more reactive and takes its place leading to the formation of iron sulfate.

It is present on the World Health Organization’s list of essential medicines as the safest and effective drugs necessary in the health sector. In 2018, with more than 8 million prescriptions, it was the 94th most widely prescribed drug in the United States.

Properties of Ferrous Sulphate

  • The chemical formula of the ferrous sulphate is \(-{FeSO_4}\)
  • Its Molar mass is – 151.908 g/mol.
  • The density of ferrous sulphate is \({2.84 g/cm^3}\)
  • Colour/Appearance of ferrous sulphate –

Anhydrous – White crystals

Monohydrate – Yellowish white crystals

Heptahydrate – Bluish-green crystals.

  • Odour – It is odourless
  • The Melting point of ferrous sulphate is 56-64\degree C.
  • The Boiling point of the ferrous sulphate is >300\degree C.
  • Covalently-Bonded Unit – 2
  • Hydrogen Bond Acceptor – 4
  • It is soluble in water.

Hydrates of Ferrous Sulphate

Iron(II) sulfate is available in several states of hydrations, and some of these types occur in nature. Such as;

\({FeSO_4 \cdot H_2O}\) (Szomolnokite, relatively rare)

\({FeSO_4 \cdot 4H_2O}\) (Rozenite, white, relatively common, maybe dehydration product of melanterite)

\({FeSO_4 \cdot 5H_2O}\) (Siderotil, relatively rare)

\({FeSO_4 \cdot 6H_2O}\) (Ferrohexahydrite, relatively rare)

\({FeSO_4 \cdot 7H_2O}\) (Melanterite, blue-green, very common)

Tetrahydrate is stable when the temperature of the aqueous solution exceeds \({56.6 \degree C} {(133.9 \degree F)}\). The solution forms both tetrahydrate and monohydrate at \({64.8 \degree C} {(148.6 \degree F)}\).

All of the mineral types listed link with the oxidation zones of iron-bearing ore beds(marcasite) and related environment (like coal fire sites). Many undergo accelerated dehydration and occasionally oxidation. Numerous other, more complex (either simple, hydrated and with additional cations) Fe(II)-sulphate-bearing sulphates occur in these environments, with copiapite being a good and usual example.

Production of Ferrous Sulphate

When steel finishing before plating or coating, the steel sheet or rod passes through the sulphuric acid pickling baths. It generates a significant amount of iron(II) sulfate as a by-product.

\({Fe + H_2SO_4 \longrightarrow FeSO_4 + H_2}\)

Another source of production of large amounts is the production of titanium dioxide from ilmenite by the sulfate process.

Ferrous sulfate is also produced commercially by the oxidation process of pyrite:

\({2 FeS_2 + 7 O_2 + 2 H_2O  \longrightarrow 2 FeSO_4 + 2 H_2SO_4}\)

Displacing metals that are less reactive than iron from the solutions of their sulfate can also produce ferrous sulphate:

\({CuSO_4 + Fe  \longrightarrow FeSO_4 + Cu}\)


Industrially, ferrous sulfate is mostly useful as a precursor to other iron compounds. It is a reducing agent and is also for the reduction of chromate in cement to a less toxic Cr(III) substance. Historically, ferrous sulfate has been in use as a dye fixative in the textile industry for centuries. And for blackening the leather and as a source of ink. The processing of sulphuric acid by the distillation of green vitriol (Iron(II) sulfate) is a well-known method for more than 700 years.

Medical Use

Iron is an essential heavy metal that is useful in several over-the-counter multi-vitamin and mineral supplements. It is also in use therapeutically at higher doses to cure or avoid iron-deficiency anaemia. When consumed at the usual prescribed daily intake or at the replacement dosage, iron has little or no adverse effect on the liver. In high doses and intentional or unintentional overdosages, iron causes severe toxicity, one such factor of which is acute liver failure.

Impheron and iron dextran are injectable iron supplements. Ferrous fumarate, ferrous gluconate and ferrous sulphate are the most common oral iron supplements. Ferrous sulfate is by far the safest and cheapest supplement for iron.

Plants Growth

Iron (II) sulfate or ferrous sulfate, is a soil alteration to lower the pH of high alkaline soil so that plants can absorb soil’s nutrients. It is useful for treating iron chlorosis in horticulture. Though not as fast-acting as ferric EDTA, its effects are longer-lasting. It can be combined with compost and dug into the soil to create a store that can last for years.

Other Uses

  1. Ferrous sulfate introduction into the cooling water running through the turbine condenser tubes to create a corrosion-resistant protective layer.
  2. It is useful in gold refining for precipitating metallic gold from auric chloride solutions (gold dissolved in solution with aqua regia).
  3. It has been in use for the purification of water by flocculation and for the elimination of phosphates in municipal and industrial sewage treatment plants to avoid the eutrophication of water bodies.
  4. Useful as a traditional way of treating wood panelling on houses, either individually, dissolved in water or as an element of water-based paint.
  5. Green vitriol is also a useful reagent for the detection of mushrooms.
  6. It is useful as an iron catalyst element of the Fenton reagent.
  7. It’s one of the most necessary ingredients in the ink of iron gall.

FAQs about Ferrous Sulphate

Question.1. What are the benefits of ferrous sulfate?

Answer. Myoglobin allows storing oxygen in the muscle cells. Ferrous sulfate is a mineral that is essential to the body. Ferrous sulfate is useful in curing iron deficiency anaemia, which is the lack of red blood cells triggered by the less iron content in the body. It can also be useful for uses other than those listed here.

Question.2. Why is iron called ferrous?

Answer. Usually, “ferrous” means “containing iron” the expression comes from the Latin word Ferrum (‘iron’). Ferrous metals involve steel and pig iron (with a carbon content of a few per cent) and iron alloys with many other metals (such as stainless steel).

Question.3. What are the benefits of ferrous sulphate?

Answer. The primary benefit of using ferrous sulfate supplement is to maintain normal iron levels in the body.

  • It helps in maintaining normal iron levels in the blood.
  • It may even prevent symptoms of iron deficiency.
  • Also, it is useful in treating iron-deficiency anaemia.

Question.4. What are the side effects of overdosage of ferrous sulphate?

Answer. The most common side effects reported by people include different types of gastrointestinal distress, including nausea, diarrhoea, vomiting, stomach pain, constipation, and black or discoloured stools.

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