Brief notes on Potassium Dichromate formula And Molecular Structure

Potassium dichromate is a potassium chemical. It is a commonly revered chemical reagent in inorganic chemistry. It is a powerful oxidising agent. Thus, the same can easily be used in numerous labs and industries anytime oxidation is involved. Potassium dichromate can harm humans’ health if exposed for an extended period; consequently, it must be handled with extreme caution. It is a brilliant orange-red colour that appeals to the eyes. It is commonly utilised in analytical chemistry due to its non-deliquescent character. Potassium dichromate is made from chromates created by treating chromite ore with sodium or potassium carbonate.

Potassium Dichromate

Potassium dichromate is a hexavalent chromium compound used as an inorganic chemical reagent. K2Cr2O7 is the potassium dichromate formula. It is employed in various industrial applications and laboratories as a typical oxidising agent. Because potassium dichromate is hexavalent, it is poisonous and detrimental to the skin and body. Potassium dichromate is a crystalline ionic solid with a striking red-orange hue. Compared to most industry-relevant sodium dichromate salts, potassium dichromate is more common in laboratory research since it is not deliquescent (a tendency to absorb air moisture and dissolve in it). Potassium dichromate is produced by reacting potassium chloride with sodium dichromate.

                Na2Cr2O7 + 2KCl → K2Cr2O7 + 2NaCl

It may also be made from potassium chromate by burning chromite ore with potassium hydroxide. It ionises in water as follows:

              K2Cr2O7 → 2K+ + Cr2O72−

              Cr2O72- + H2O ⇌ 2CrO42- + 2H+

In the laboratory, this reaction produces orange-red crystals of potassium dichromate. It dissolves in water. It does not have a distinct odour. It may, however, cause significant irritation in the eyes and respiratory tract. Potassium dichromate should not come into contact with organic compounds. It is noncombustible yet, with tungsten and iron, is widely used in pyrotechnic displays.

Potassium Dichromate’s Structure 

Potassium dichromate has the chemical formula K2Cr2O7 and a molar mass of 294.185 g/mol. It is an ionic molecule composed of two potassium ions (K+) and the negatively charged dichromate ion( Cr2O72-), with two hexavalent chromium atoms (with oxidation state +6), each one that is connected to three atoms of oxygen and a bridging atom of oxygen.

Chemical Characteristics

Heat Action: When heated, K2Cr2O7  decomposes to generate potassium chromate with the emission of O2 gas.

4  K2Cr2O7  → 4K2CrO4 + 2Cr2O3 + 3O2

When an orange-red solution of K2Cr2O7  combines with an alkali, a yellow solution is formed due to the creation of potassium chromate.

         K2Cr2O7 + 2KOH   →  2 K2CrO4 + H2O

The yellow hue of K2CrO4 turns orange-red when acidified due to the reformation of   K2Cr2O7

        2K2CrO4 + H2SO4 → K2Cr2O7 + K2SO4 + H2

The interconversion can be explained because orange-red Cr2O72- ions are in equilibrium with yellow CrO42- ions in the K2Cr2O7 solution.

               Cr2O72- + H2O → 2CrO42- + 2H+

Orange-red            Yellow

Potassium Dichromate Applications (K2Cr2O7 )

The applications of this particular chemical compound can easily be attributed to the combined uses of the components. Potassium dichromate is widely used in industry. 

Some of its uses are as follows:

• In labs and industries, K2Cr2O7  is used as an oxidising agent in several processes.
• It’s a volumetric analysis tool.
• It is used in the dyeing and calico printing processes.
• In photography, K2Cr2O7 is used as an oxidising agent with a strong mineral acid to harden the gelatin film.
• It is used to make chromic acid, which is used to clean glassware (together with other chromium (VI) compounds such as sodium dichromate and chromium trioxide). However, because of the very nature of the components, this technique is now discouraged and prohibited.
• In the building business,  K2Cr2O7  is used as a component in cement.
• It is a non-hygroscopic reagent used in analytical chemistry “wet experiments.”
• It is utilised as a darkening wood agent in wood tannins, which results in rich brown colour on wood. It is an efficient mahogany treatment.

Conclusion

All chemical compounds are unique in their respects. Potassium dichromate can lead to chronic infections such as chromium dermatitis on the hands and lower arms.

The toxicity of potassium dichromate can affect animals such as rabbits and rats.

It is also hazardous to amphibians and poses a significant environmental threat.

Potassium dichromate is toxic, and its exposure may cause a few eye problems or vision impairment. Some researchers suggest that it is also carcinogenic.