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Chromate Formula - Properties, Structure, Uses

Chromate, also known as chromium oxoanions, is an inorganic salt containing chromic acid with a distinctive yellow hue. Its oxidation state is six plus, and it is formed when protons are removed from chromic acid.
authorImageSawat Sayyed27 Sept, 2023
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Chromate Formula - Properties, Structure, Uses

Chromates are the salts of chromic acid that contain the chromate anion with the chemical formula CrO42– and usually have an intense yellow color. Sodium and potassium salts of chromate are the most commonly used chromate salts. The oxoanion is generated when protons are removed from chromic acid. It is also known as chromium oxoanion and divalent inorganic anions.

Chromate Structure – CrO 42-

As a result of the removal of two protons from chromic acid, chromate is the salt of chromic acids. The chromium oxo anion is converted into a divalent inorganic anion with the chemical formula CrO42-. Many polyatomic ions are used to form insoluble salts. Among the chromate salts are sodium salts and potassium salts. Chromate has an intense yellow color and is a powerful oxidizing agent.

Chromate Ion

In the realm of chemistry, chromate falls in the category of inorganic salts. Acids and bases combine to create neutral ionic compounds called salts. Those lacking carbon-hydrogen bonds are referred to as inorganic salts, while those containing these bonds are known as organic salts. When an acid interacts with a base, it produces inorganic salts. Additionally, acids may also react with metals, forming inorganic salts. Some well-known examples of mineral salts include sodium chloride, potassium chloride, calcium chloride, and others formed by combining sodium, potassium, or calcium with chlorine. Chromate ion The acid A and the base B combine to form salt AB and release water. AH+BOH = AB+H2O

Also Check - Chloroacetic Acid Formula

What is Chromate Formula?

Chromate, also known as chromium oxoanions, is an inorganic salt containing chromic acid with a distinctive yellow hue. Its oxidation state is six plus, and it is formed when protons are removed from chromic acid. The IUPAC name for chromate is dioxo chromium, and its molecular weight is 194.18 g/mol. The formula for chromate anion is CrO42-.
CrO42- Chromate
Density 2.73 g/cm³
Molecular Weight/ Molar Mass 194.1896 g/mol
Conjugate acid‎ ‎Chromic acid (H2CrO4)
Oxidation State +6
Chemical Formula CrO42-

Also Check - Urethane Formula

Physical Properties of Chromate – CrO42-

Odour Odourless
Appearance Yellow powder
Valency 2
Solubility Generally insoluble in water.
In general, chromate is readily soluble in water (H2O), and is easily identifiable by its yellowish color or yellow powder. Chromate is odourless. Due to the removal of two protons from chromic acid, chromate has a valency of two. This molecule's topological polar surface area is 80.3 and the number of heavy atoms is five.

Chemical Properties of Chromate

Chromate has a variety of chemical properties. It also has a variation known as dichromate salts that possess dichromate anion. In acidic solutions, its ion works as a firm oxidizing agent.  Upon combining it with water, we can observe that it forms chromium(III) hydroxide. CrO42- + 4H2O + 3e-  ---> Cr(OH)3 + 5OH- We can create potassium nitrate and barium chromate by reacting potassium chromate with barium nitrate. K2CrO4 + Ba(NO3)2 <---> BaCrO4+ 2KNO3 It also combines with other elements to form ammonium, sodium, and calcium chromate.

Also Check - Acetylene Formula

Uses of Chromate Formula

Chromate has many uses, including forming a pretreatment layer to create a protective coating on surfaces. These salts, such as potassium, sodium, calcium, and ammonium, have excellent corrosive properties and serve as an adhesive between metal and primer to prevent corrosion. Despite their long-lasting effects and self-healing capabilities, they can deplete upon damage. Industries commonly deposit these coatings on materials, although it is important to note that chromate can be hazardous to health. However, this method is still used in products such as rustproofing materials and enamels for corrosion prevention. The salts can also form pigments for ink or dye due to their oxidizing property and low solubility. As they are highly toxic for health, it is important not to consume these products. In fact, even industrial crayons may contain chromate salts that are harmful if ingested. Another common use of chromate is in the process of chromate plating, which protects everyday items from rust and decay by utilizing the beneficial properties of chromium salts.

Chromate Formula FAQs

What is the structural formula of chromate ion (CrO4^2-)?

The structural formula of the chromate ion (CrO4^2-) consists of one chromium (Cr) atom bonded to four oxygen (O) atoms in a tetrahedral arrangement.

What is the charge on the chromate ion (CrO4^2-)?

The chromate ion carries a charge of -2, indicated by the superscript 2- in its chemical formula. This charge results from combining one chromium atom with four oxygen atoms.
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