Potassium Chromate - K₂CrO₄

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Introduction to Potassium Chromate

Potassium chromate can be described as an inorganic compound having the chemical formula K2CrO4. Potassium chromate is a yellow crystalline solid, and it is soluble in water. The primary hazard is an environmental danger, where immediate measures on its spread; restriction to the setting should be taken. In chemical analysis, it is used as a fungicide, making pigments for inks and paints and creating other chromium compounds.


Potassium chromate is a substance, which is the recognized cause of human cancers. It is also linked with an enhanced danger of developing cancer of the sinonasal cavity and lung cancer.


What is Potassium Chromate?

Potassium chromate can be defined as an inorganic compound having a chemical formula K2CrO4. It can also be called either bi-potassium chromate or dipotassium monochromatic. It appears as a crystalline solid, which seems to be yellow in colour. It tastes bitter and has no smell. When this compound is heated, it emits toxic chromium fumes. It also undergoes decomposition upon heating and emits toxic fumes of potassium oxide.


When this inorganic compound comes into contact, it can affect our nose, lungs, throat, causing bronchitis, ulcerations, shortness of breath, pneumonia, and asthma. It can also affect our liver, kidneys, gastrointestinal tract, including the immune system. It holds chromate and potassium ions in a ratio of 1:2. It can be widely used as a laboratory chemical, and it is a strong oxidizing agent. It is also highly corrosive. The chemical name of K2CrO4 is Potassium Chromate.


Structure of Potassium Chromate – K2CrO4

Potassium chromate contains 1 chromate anion (CrO42- ion) and 2 positively charged potassium cations (K+ ions). The chromate anion is made up of 1 chromium atom and 4 oxygen atoms. In the polyatomic ion, the central chromium atom is doubly bonded to 2 oxygen atoms and singly bonded to 2 oxygen atoms, whereas the singly bonded oxygen atoms hold a charge of -1 (it enables them to obtain the complete octet configurations).

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A few of the important properties of Potassium Chromate are tabulated below.


Properties of Potassium Chromate K2CrO4

IUPAC Name or K2CrO4 chemical name

Potassium chromate

Chemical Formula

K2CrO4

Molecular Weight or Molar Mass

194.1896 g/mol

Boiling Point

1,000°C

Melting Point

968°C

Density

2.7320 g/cm³

K2CrO4 Compound Name

Potassium Chromate


Some other important properties of potassium chromate compounds are listed below.

  • This compound appears as a yellow, powdery appearance, and it is odourless.

  • At 20⁰C temperature, in water, this compound holds a solubility of 629 grams per litre.

  • When the temperature is increased to 100⁰C, the potassium chromate's solubility in water increases to 792 grams per litre.

  • K2CrO4 also crystallizes in a rhombic lattice.

Potassium chromate is produced by treating potassium dichromate, including potassium hydroxide. And, the most common oxidation state of chromium is +2, +3, +6, and the electronic configuration of chromium is given as 3d54s1 with the atomic number is 24. Potassium chromate compound is a powerful oxidizing agent and is extremely corrosive. This material can be used in the production'>production of colourants and in textile dyeing procedures. The chemical formula for potassium chromate is given as K2CrO4.


K2CrO4 Uses (Potassium Chromate)

The important potassium chromate uses are listed below.

  • It can be used in the qualitative inorganic analysis in the detection of the ions in an aqueous solution.

  • We can use it as an oxidizing agent during organic synthesis.

  • It can be used in dyes manufacturing.

  • We can use it in the process of textile dyeing.

  • It is also used as an indicator in precipitation titrations.

  • It can be used in making pigments and inks for paints.

  • This compound can be used to make many other chromium compounds.

  • It is also used as a fungicide.

  • It can be used in the leaching process.

Health Hazards of K2CrO4

  • Potassium chromate is a well-known human carcinogen, and this compound is associated with an increased risk of developing sinonasal cavity cancer and also lung cancer.

Potassium Chromate Indicator

Potassium chromate can be described as a metalochrome indicator. The quantitative estimation of the ions: chloride, bromide, and cyanide by titrating with a standard solution of silver-nitrate'>silver nitrate with a few millilitres of potassium chromate as an indicator form the basis of Mohr's method. Also, the yellow-coloured solution of potassium chromate changes into to brick-red precipitate of silver chromate at the equivalence point.


When the potassium chromate compound is used as an indicator after the chloride ion's extinction, the silver ions react with chromate ions, and the silver chromate's solubility product is exceeded, and it starts to form a precipitate of reddish-brown in colour.


In the precipitation titration, a known volume of halide solution is taken in a conical flask, where 1-2ml of potassium chromate indicator is added and titrated against a standard solution of silver nitrate, which is taken in the burette. The indicator then produces a red-coloured precipitate of silver chromate at the endpoint by excess drops of silver nitrate added.


Foods that Contain Natural Potassium Carbonate

Potassium carbonate, which can be used for softening, baking, buffering, is given as synthetic. This compound is more beneficial and can be used for general well being. It is also synthetic and available in the form of supplements. However, there are many rich potassium carbonate-containing food sources such as baked potato skins, bananas, sunflower seeds, and almonds.


What Happens if Potassium Carbonate is Heated Strongly?

The potassium carbonate compound melts at 891 Celsius. It gives a notation of ‘d,’ for its boiling point, which means as decomposes, but there is no evidence about the specific temperature. Its product decomposition would be carbon dioxide, including a form of potassium oxide (K2O3, K2O, and others), where the more stable potassium oxide form is seemed to be K2O3. It is the only compound that doesn’t appear to decompose when heated.


As the decomposition making potassium, which is not an oxide, metallic potassium does not remain longer, unchanged in air. Usually, it is stored in mineral oil to keep oxygen and water away from it. In the air that contains moisture, potassium will tend to become a hydroxide or oxide.

FAQ (Frequently Asked Questions)

Q1. Is Potassium Chromate Aqueous?

Ans. Potassium chromate can be defined as a yellow crystalline solid, and it is soluble in water. The primary danger due to this compound is an environmental threat. If it happens, immediate steps should be taken to minimize their spread to the ecosystem.

Q2. Is Potassium Chromate an Acid or Base?

Ans. Commonly, potassium chromate is referred to as tarapacaite, which is an inorganic compound at room temperature, which means either yellow orthorhombic or hexagonal crystal. This compound's absolute density is given as 2,732, and it has a melting point of 968 ° C. It is poisonous, and it can dissolve into water to further form a solution for hydrolysis of alkaline chromate ions.

Q3. What Colour is Potassium Chromate?

Ans. Potassium chromate is simply the yellow base of chromate anion of potassium chloride. It is also a growing chemical in the laboratory, while the industrial sodium chromate is quite essential.

Q4. Is Potassium Chromate Hazardous?

Ans. Potassium chromate is a compound, which is highly toxic to aquatic organisms and may cause aquatic environmental effects in the long-term.

Q5. Why Potassium Chromate Compound is Used as an Indicator?

Ans. Potassium Chromate can be used as an indicator with a solution of regular Silver Nitrate to assess chloride by titration.

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