Sodium Dichromate: Structure, Production, Uses and Properties

Sodium Dichromate, with the formula Na₂Cr₂O₇ is an inorganic compound. It has a red or an orangish appearance. It is an oxidizing agent of strong nature and is highly corrosive in nature. Sodium Dichromate helps in producing other chromium compounds. It also helps in the production of other organic compounds, dyes, wood preservatives, and is used as a corrosion inhibitor. It is also used for metal treatments. In this article, we will learn more about sodium dichromate, its uses, production, and properties.

Read More: Metals and Non-Metals

Keyterms: Sodium, Oxidizing agent, Chromium, Compounds, Inorganic compound, Corrosion inhibitor

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What is Sodium Dichromate?

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Sodium dichromate is an inorganic compound containing 2 sodium atoms, 2 chromium atoms, and 7 oxygen atoms having its chemical formula as (Na₂Cr₂O₇). Sodium Dichromate, Na₂Cr₂O₇, is a crystalline solid and has an orange to red appearance. Due to the presence of 7 oxygen atoms, the sodium dichromate compound acts as a strong oxidizing agent because it has many oxygen to give to other species to oxidize them by reducing itself.

Sodium Dichromate

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Properties of Sodium Dichromate

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Uses Of Sodium Dichromate

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Sodium dichromate is used for a variety of purposes such as:

• It is mainly used to make chromium compounds.
• The compound is used for drilling muds.
• Sodium dichromate is used for treating metals.
• It is also used in the production of dyes.
• Sodium dichromate is used in the production of organic chemicals
• It is generally used as a corrosion inhibitor to prevent corrosion in metals.
• Sodium dichromate is used by many dye-producing industries.
• It is also used for plating (a thin layer of this compound is applied on the different metallic items to prevent rusting or corrosion).
• The compound is used in the petroleum industry because of its high oxidizing nature.
• Sodium Dichromate is also used in ceramic industries to produce colored glass and ceramic glaze.

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Structure of Sodium Dichromate

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The structure of Sodium Dichromate, Na₂Cr₂O₇, is as shown below:

Structure of Sodium Dichromate

The bond lines represent the covalent bond between chromium and oxygen atoms which makes the valency of chromium 12, the number of electrons in the outermost shell or the farthermost shell of the atom (this is an exception and doesn’t follow the octet rule). The Na and O become ions and are held together by the force of attraction (ionic bond).

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Production of Sodium Dichromate

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Sodium Dichromate, Na₂Cr₂O₇, is mainly obtained from ores in the earth. But several steps are performed for its production which are as follows:

1. The first step includes the fusion of ore with sodium carbonate, which is basic in nature.
2. The ore is then heated at a very high temperature of 1000 degrees Celsius in the presence of air because oxygen is needed in huge amounts for the process.
3. The reaction that takes place is 

2Cr₂O₃ + 4Na₂CO₃ + 3O₂ → 4Na₂CrO₄ + 4CO₂

These steps solubilize chromium and then extract it in hot water.

2Na₂CrO₄ + 4CO + H₂O → Na₂CrO₇ + 2NaHCO₃

2Na₂CrO₄ + H₂SO4 → Na₂CrO₇ + Na₂SO₄ + H₂O

Acidification of the aqueous extract helps to produce dichromate.

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Health Hazards of Sodium Dichromate

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• Sodium dichromate is a well-known human carcinogen 
• It is also associated with an increased risk of developing lung cancer.
• Cancer of the sinonasal cavity is also caused by the accumulation of sodium dichromate in the human body.
• Sodium dichromate can affect the respiratory system
• It can also cause ulcers in the human body if accumulated.
• Sodium dichromate can cause shortness of breath or other lung diseases when it enters the respiratory tract and can result in causing bronchitis.
• Pneumonia is also caused by sodium dichromate. 
• It causes asthma and other respiratory disorder of high risk.
• It can also affect the gastrointestinal tract and causes harm to the liver.
• Sodium dichromate causes severe damage to the kidneys and causes stone and creates problems in process of filtration
• The compound causes damage to our immune system in many more ways.

Read More: Human Digestive System

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Things to Remember

• Sodium dichromate is an inorganic compound and its chemical formula  is Na₂Cr₂O₇. 
• It is used for the production of chromium compounds, dye production, organic chemical production, forming a protective layer for metals, etc.
• The reactions that take place during the formation of Sodium dichromate are:  

2Cr₂O₃ + 4Na₂CO₃ + 3O₂ → 4Na₂CrO₄ + 4CO₂ 

2Na₂CrO₄ + H₂SO₄ → Na₂CrO₇ + Na₂SO₄ + H₂O

• Sodium dichromate can cause severe damage to the human body if is accumulated in the body and is a known carcinogen that causes cancer and eventually results in the death of people who works in its extraction and reactions without any safety gears.
• The acidification of the aqueous extract helps to produce dichromate:

2Na₂CrO₄ + H₂SO₄ → Na₂Cr₂O₇ + Na₂SO₄ + H₂O

• Methanol and ethanol can be detected with the help of sodium dichromate. If the compound smells irritating and pungent after adding and mixing the alcoholic solution with Na₂Cr₂O₇ + H₂SO₄ then methanol presence is confirmed and if the smell is fruity then the ethanol is detected.