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Cobalt (II) Sulfate Formula

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  • Last Updated : 08 Sep, 2022
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Cobalt(II) sulfate also termed cobaltous sulfate or cobalt sulfate is a toxic and metallic salt. It is an inorganic compound whose chemical formula is CoSO4 or CoO4S. It is a sulfate compound that consists of cobalt (+2 oxidation state) and sulfate in the ratio of 1:1. It is an odourless, and rose-pink solid. It sinks and mixes with water while it slowly dissolves in boiling water. Its hydrates are heptahydrate, hexahydrate, and monohydrate. Heptahydrate of cobalt (II) sulfate is the most commonly available cobalt salt. This is insoluble in ammonia and soluble in methanol. On heating to 735 °C, it decomposes and produces toxic fumes of sulfur oxides. It is used in the manufacture of pigments, as a catalyst, as a paint and ink drier, and as a soil additive. It is also used as a supplement for Vitamin B12 deficiency and in storage batteries. Exposure to cobalt(II) sulfate may irritate the eyes, skin, and respiratory tract, and also it may affect the lungs, heart, and kidneys.

Structure of Cobalt (II) Sulfate

Cobalt (II) Sulfate formula

Cobalt (II) Sulfate formula

Preparation of Cobalt (II) Sulfate

  • Cobalt (II) Sulfate can be prepared by the action of aqueous sulfuric acid on cobaltous oxide.

CoO + H2SO4 + 6H2O → CoSO4(H2O)7

  • It can also be prepared by the interaction of metallic cobalt, its hydroxide, or carbonate with aqueous sulfuric acid.

Co + H2SO4 + 7H2O → CoSO4(H2O)7 + H2

  • The heptahydrate transforms into hexahydrate if the humidity is below 70% at room temperature. Whereas the hexahydrate transforms into the monohydrate and anhydrous forms at 100 and 250 °C, respectively.

CoSO4(H2O)7 → CoSO4(H2O)6 + H2O
CoSO4(H2O)6 → CoSO4(H2O) + 5H2O
CoSO4(H2O) → CoSO4 + H2O

Properties of Cobalt (II) Sulfate

Chemical formula   CoSO4·(H2O)n (n=0,1,6,7)
IUPAC Name Cobalt(II) sulfate
Molar mass  154.996 g/mol (anhydrous)
173.01 g/mol (monohydrate)
263.08 g/mol (hexahydrate)
281.103 g/mol (heptahydrate)
Density  3.71 g/cm3 (anhydrous)
3.075 g/cm3 (monohydrate)
2.019 g/cm3 (hexahydrate)
1.948 g/cm3 (heptahydrate)
Appearance  Reddish crystalline (anhydrous, monohydrate) 
pink salt (hexahydrate) 
Odour  Odourless
Melting point 735 °C

Chemical Properties of Cobalt (II) Sulfate

  • At a temperature of 600–700 °C, cobalt (II) sulfate decomposes to produce oxygen, sulfur dioxide, and cobaltous oxide, or cobalt (II) oxide.

2CoSO4 → O2 + 2SO2 + 2CoO

  • Cobalt (II) sulfate reacts with sodium hydroxide to produce sodium sulfate and cobalt (II) hydroxide.

2NaOH + CoSO4 → Na2SO4 + Co(OH)2

  • Cobalt (II) sulfate reacts with the aluminium hydroxide to produce cobalt(II) aluminium oxide, sulfur dioxide, oxygen, and water.

4Al(OH)3 + 2CoSO4 → 2CoAl2O4 + 2SO2 + O2 + 6H2O

  • When cobalt(II) sulfate is treated with a concentrated solution of ammonium hydroxide, hexaamminecobalt(II) sulfate and water are formed.

6NH4OH + CoSO4 → 6H2O + [Co(NH3)6]SO4

  • When cobalt(II) sulfate interacts with lead nitrate, lead sulfate and cobalt(II) nitrate are formed.

CoSO4 + Pb(NO3)2 → PbSO4 + Co(NO3)2

Uses of Cobalt (II) Sulfate

  • Hydrated cobalt(II) sulfate is used in the manufacture of pigments (ceramics, glazes, and enamels).
  • It is also used in the preparation of various cobalt salts.
  • It is used in electroplating and storage batteries.
  • It is also used as a catalyst, a paint, and ink drier, and as a soil additive.
  • It can also be used as veterinary medicine to prevent and treat cobalt deficiency in ruminants.

For all the above purposes, cobalt (II) sulfate is produced by treating cobaltous oxide with sulfuric acid.

Health Hazards

  • Although cobalt is an essential mineral for mammals, more than a few micrograms per day can be harmful.
  • It irritates the eyes or skin as it comes into contact with them.
  • Breathing difficulties, coughing, and respiratory tract may result from inhalation.
  • Ingestion may cause pain and vomiting. It may also harm the kidneys, lungs, and heart.

FAQs on Cobalt (II) Sulfate Formula

Question 1: What is cobalt (II) sulfate?

Answer:

Cobalt (II) sulfate also termed cobaltous sulfate or cobalt sulfate is a toxic and metallic salt. It is an inorganic compound whose chemical formula is CoSO4 or CoO4S. It is a colorless, odorless, and rose-pink solid. It sinks and mixes with water while it slowly dissolves in boiling water. Its hydrates are heptahydrate, hexahydrate, and monohydrate. This is insoluble in ammonia and soluble in methanol. On heating to 735 °C, it decomposes and produces toxic fumes of sulfur oxides.

Question 2: How is cobalt (II) sulfate prepared?

Answer:

Cobalt (II) Sulfate can be prepared by the action of aqueous sulfuric acid on cobaltous oxide.

CoO + H2SO4 + 6H2O → CoSO4(H2O)7

It can also be prepared by the interaction of metallic cobalt, its hydroxide, or carbonate with aqueous sulfuric acid.

Co + H2SO4 + 7H2O → CoSO4(H2O)7 + H2

The heptahydrate transforms into hexahydrate if the humidity is below 70% at room temperature. Whereas the hexahydrate transforms into the monohydrate and anhydrous forms at 100 and 250 °C, respectively.

CoSO4(H2O)7 → CoSO4(H2O)6 + H2O
CoSO4(H2O)6 → CoSO4(H2O) + 5H2O
CoSO4(H2O) → CoSO4 + H2O

Question 3: What happens when cobalt(II) sulfate is treated with a concentrated solution of ammonium hydroxide?

Answer:

When cobalt(II) sulfate is treated with a concentrated solution of ammonium hydroxide, hexaamminecobalt(II) sulfate and water are formed.

6NH4OH + CoSO4 → 6H2O + [Co(NH3)6]SO4

Question 4: What are the uses of cobalt(II) sulfate?

Answer:

Hydrated cobalt(II) sulfate is used in the manufacture of pigments (ceramics, glazes, and enamels). It is also used in the preparation of various cobalt salts. It is used in electroplating and storage batteries. It is also used as a catalyst, a paint, and ink drier, and as a soil additive. It can also be used as veterinary medicine to prevent and treat cobalt deficiency in ruminants.

Question 5: What happens when cobalt (II) sulfate is heated to decompose?

Answer:

At a temperature of 600–700 °C, cobalt (II) sulfate decomposes to produce oxygen, sulfur dioxide, and cobaltous oxide, or cobalt (II) oxide.

2CoSO4 → O2 + 2SO2 + 2CoO

Question 6: Mention some health hazards of cobalt (II) sulfate.

Answer:

Although cobalt is an essential mineral for mammals, more than a few micrograms per day can be harmful. It irritates the eyes or skin as it comes into contact with them. Breathing difficulties, coughing, and respiratory tract may result from inhalation. Ingestion may cause pain and vomiting. It may also harm the kidneys, lungs, and heart.


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