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Iron III Sulfate Formula

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Iron(III) Sulfate is an inorganic compound that is also termed ferric sulfate. Its chemical formula is Fe2(SO4)3. In iron III sulfate, each iron atom has ionic bonds with the sulfate. A variety of hydrates of iron III sulfate are known, such as nonahydrate, anhydrous monohydrate, etc. In fact, they are the most commonly encountered form of “Iron III Sulfate”. It is slightly soluble in water and very hygroscopic. It is sparingly soluble in alcohol and negligibly soluble in acetone and ethyl acetate. It is not soluble in sulfuric acid and ammonia. As iron III sulfate is insoluble in sulfuric acid, it is used for producing iron III sulfate. It emits toxic fumes of iron and sulfur oxide when heated to decomposition. It is a threat to the environment and immediate steps should be taken to control its spread in the environment. It is used as a coagulant in water purification, as an astringent, and as a soil conditioner. It is corrosive to copper, copper alloys, mild steel, and galvanized steel.

Structure of Iron (III) Sulfate

The chemical formula of Iron(III) Sulfate is Fe2(SO4)3, which has Fe+3 cations and (SO4)-2 anions that form a crystalline salt with rhomboidal geometry. Its molecular formula is Fe2O12S3. The ratio of iron and sulfate ions in Iron III Sulfate is 3:2.

Iron III Sulphate structure

Iron III Sulphate structure

Preparation of Iron (III) Sulfate

Naturally, iron sulfates are found in a variety of rare and commercially unimportant minerals. However, iron III sulfate is mainly found in minerals like pyrite and marcasite. In general, iron III sulfates are used as a solution that is generated from iron wastes. Although the actual specification is vague, its applications do not require high-purity materials.

On a large scale, iron III sulfates are prepared by treating sulfuric acid with a hot solution of iron(II) sulfate and an oxidizing agent. Hydrogen peroxide, chlorine, and nitric acid are some of the typical oxidizing agents used in the preparation of iron III sulfate.

2FeSO4 + H2SO4 + H2O2 → Fe2(SO4)3 + 2H2O

It can also be prepared industrially by injecting chlorine gas into an iron(II) sulfate solution, resulting in a mixture of iron(III) sulfate and iron(III) chloride.

3Cl2 + 6FeSO4 → 2Fe2(SO4)3 + 2FeCl3

Properties of Iron (III) Sulfate

 Chemical Formula  Fe2(SO4)3
  IUPAC name   Iron(III) sulfate 
 Appearance   yellow crystalline solid or greyish-white crystals 
 Molar Mass/Molecular weight  399.88 g/mol (anhydrous)
489.96 g/mol (pentahydrate)
562 g/mol (nonahydrate)
 Density 3.097 g/cm3 (anhydrous)
1.898 g/cm3 (pentahydrate)
 Melting point  480 °C (anhydrous)
175 °C (nonahydrate)
 Solubility in Water   Slightly Soluble
 Refractive index   1.814 (anhydrous)
1.552 (nonahydrate)

Other Experimental Properties and Reactions

  • When iron(III) sulfate is heated to decomposition, it produces iron(III) oxide, sulfur dioxide, and oxygen. This reaction occurs at a temperature between 900 and 1000 °C.

2Fe2(SO4)3 → 2Fe2O3 + 6SO2 + 3O2

  • Barium carbonate (BaCO3) reacts with iron III sulfates to produce white precipitates of barium sulfate and ferric carbonate.

3BaCO3 + Fe2(SO4)3 → 3BaSO4 + Fe2(CO3)3

  • Iron III sulfate reacts with sodium sulfide (Na2S) to form ferrous sulfide, sodium sulfate, and sulfur.

Fe2(SO4)3 + 3Na2S → 2FeS + 3Na2SO4 + 2S 

  • The following reaction takes place when iron III sulfate is added to water.

Fe2(SO4)3 + 3Ca(HCO3)2 → 2Al(OH)3↓ + 3CaSO4↓ + 6CO2

Uses of Iron III Sulfate

  • Iron III Sulfate is mainly used as a coagulant in water purification and sewage treatment. 
  • The solution of ferric sulfate is used as a mordant in dyeing and calico printing. 
  • It is also used in the preparation of iron salts and pigments, in the ferric salt leaching process, in soil conditioners, and in the coal conversion process. 
  • It acts as a disinfectant, polymerization catalyst, and hemostatic agent for endodontic surgery. 
  • It is also used in etching aluminium and in pickling stainless steel and copper.
  • It is also used as a solids removal agent and oxidizing agent.

Hazards

  • Iron III sulfate is a threat to the environment and immediate steps should be taken to control its spread in the environment.
  • Though Iron III Sulfate is a stable, not flammable compound, it emits toxic fumes of iron and sulfur oxide when heated to decomposition. 
  • Prolonged exposure to Iron III Sulfate is toxic to the lungs and mucous membranes and may cause damage to them.
  • Contact with this causes skin irritation and may also cause an allergic skin reaction. 
  • Inhalation of its dust irritates the nose and throat, and its ingestion irritates the mouth and stomach. 
  • It is harmful to aquatic life with long-lasting effects.

FAQs on Iron Sulfate Formula

Question 1: What is Iron III Sulfate?

Answer:

Iron III Sulfate is an inorganic compound that is also termed ferric sulfate. Its chemical formula is Fe2(SO4)3. In iron III sulfate, each iron atom has ionic bonds with the sulfate. It emits toxic fumes of iron and sulfur oxide when heated to decomposition. Iron III Sulfate is mainly used as a coagulant in water purification and sewage treatment.

Question 2: How is Iron III Sulfate prepared?

Answer:

Iron III sulfate is prepared on a large scale by treating sulfuric acid with a hot solution of iron(II) sulfate and an oxidizing agent. Hydrogen peroxide, chlorine, and nitric acid are some of the typical oxidizing agents used in the preparation of iron III sulfate.

2FeSO4 + H2SO4 + H2O2 → Fe2(SO4)3 + 2H2O

It can also be prepared industrially by injecting chlorine gas into an iron(II) sulfate solution, resulting in a mixture of iron(III) sulfate and iron(III) chloride.

3Cl2 + 6FeSO4 → 2Fe2(SO4)3 + 2FeCl3

Question 3: Mention some properties of Iron III Sulfate.

Answer:

Iron III Sulfate is an inorganic salt with the chemical formula Fe2(SO4)3. In iron III sulfate, each iron atom has ionic bonds with the sulfate. It is slightly soluble in water and very hygroscopic. It appears as greyish-white crystals or a yellow odorless powder. It is sparingly soluble in alcohol and negligibly soluble in acetone and ethyl acetate. It is not soluble in sulfuric acid and ammonia.

Question 4: What are the uses of Iron III Sulfate?

Answer:

  • Iron III Sulfate is mainly used as a coagulant in water purification and sewage treatment. 
  • The solution of ferric sulfate is used as a mordant in dyeing and calico printing. 
  • It is also used in the preparation of iron salts and pigments, in the ferric salt leaching process, soil conditioners, and the coal conversion process. 
  • It acts as a disinfectant, polymerization catalyst, and hemostatic agent for endodontic surgery.

Question 5: Mention some hazards of Iron III Sulfate.

Answer:

  • Iron III sulfate is a threat to the environment and immediate steps should be taken to control its spread in the environment.
  • Though Iron III Sulfate is a stable, not flammable compound, it emits toxic fumes of iron and sulfur oxide when heated to decomposition. 
  • Prolonged exposure to Iron III Sulfate is toxic to the lungs and mucous membranes and may cause damage to them.

Question 6: Write the thermal decomposition reaction of iron(III) sulfate.

Answer:

When iron(III) sulfate is heated to decomposition, it produces iron(III) oxide, sulfur dioxide, and oxygen. This reaction occurs at a temperature between 900 and 1000 °C.

2Fe2(SO4)3 → 2Fe2O3 + 6SO2 + 3O2



Last Updated : 19 Dec, 2023
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