The Applications Of Potassium Dichromate

Potassium dichromate has lower oxidising power than potassium permanganate. It is the main standard, and its solutions are stable in acid for extended periods of time and are resilient to light, most organic materials, and the chloride ion. It is always used in acidic solutions. Potassium dichromate is the dipotassium salt of dichromic acid. It has three functions – oxidant, allergen, and sensitiser. The crystals of potassium dichromate are orange-red in colour. It’s a water-soluble substance that’s also denser than water.

In inorganic chemistry, potassium dichromate is one of the most widely used chemical reagents. It’s commonly utilised as a powerful oxidising agent in a range of chemical processes in labs and businesses. In the oxidation process, potassium dichromate is a ubiquitous chemical. It’s also a major source of chromium.

History Of Potassium Dichromate

Potassium dichromate is a synthetic compound that was once used as an oxidation reaction for aniline dyes, a bleaching agent for leather tanning, and in paints like chrome yellow, chrome orange, red, and green. It was also used to make bichromate elements for batteries and photography. Potassium dichromate was employed as an astringent, antibacterial, cauterising agent in the treatment of warts and as antiperspirant foot powder in medicine.

What Is Potassium Dichromate?

Potassium dichromate is a catalyst for oxidation. The half-equation for oxidation is as follows:

Cr2O72−(aq) + 14H+ + 6e− → 2Cr3+(aq) + 7H2O +1.36 V

Potassium dichromate is a gentler oxidant than potassium permanganate in organic chemistry. It is employed in the oxidation of alcohols. When heated under reflux, it transforms primary alcohols into aldehydes or carboxylic acids. Carboxylic acids, on the other hand, are the only products of permanganate. Ketones are formed from secondary alcohols, and no further oxidation is possible. Menthone, for example, may be made by oxidising menthol with acidified dichromate.

The colour shift that occurs in an aqueous solution can be utilised to detect the presence of an aldehyde or ketone. When an aldehyde is present, the chromium ions are decreased from +6 to +3, altering the colour from orange to green. This is the case because the aldehyde may be oxidised to carboxylic acid. A ketone can’t be further oxidised; the solution stays orange.

Tertiary alcohols cannot be oxidised to produce a carbonyl group.

Applications Of Potassium Dichromate

The most common usage of K2Cr2O7 is to make potassium chrome alum, which is widely used in leather tanning. From this chemical, chromic acid may be made. Potassium dichromate is believed to be utilised in the manufacturing of cement because it enhances the texture and density of the mix.

In the photography business, potassium dichromate is employed as an oxidising agent for photographic screen printing in conjunction with a strong mineral acid. 

This non-hygroscopic chemical is also used in the field of analytical chemistry for a variety of wet experiments.

• It’s used to make potassium chrome alum, which is utilised in leather tanning.

• The chemical may be used to make chromic acid, which can be used to clean corroded glassware. However, due to safety concerns, this procedure is no longer employed.

• It’s also used to enhance the texture and solidity of cement, as well as speed up the setting time.

• The concentration of ethanol in a solution by titration method with acidified potassium dichromate is employed in the examination of the purity of a chemical sample.

• Schwerter’s solution is a mixture of potassium dichromate and 35% of nitric acid that is used to test the purity of several metals, the most important of which is silver.

• Sulphur dioxide is detected using potassium dichromate paper, which turns from orange to green when exposed to the gas.

• It’s used to turn wood into rich, varied brown tones that paints can’t match.

Uses of Potassium Dichromate

The following are the uses of potassium dichromate:

• Cleansing glassware and etching substances require chromic acid, which is made from potassium dichromate. However, due to health and safety concerns with hexavalent chromium, this method is no longer used.

• It’s used in cement to improve the density and texture of the end product by slowing the setting of the mixture.

• In volumetric analysis, it is used to estimate the volume.

• In classic “wet assays”, potassium dichromate is a popular reagent. In the leather business, it is used for chrome tanning.

• To estimate the concentration of ethanol in a sample, a black titration using acidified potassium dichromate is performed.

Schwerter’s solution is an analytical reagent created by dissolving potassium dichromate in a 35% nitric acid solution. This reagent may be used to test for the presence of several metals, particularly silver purity. When using pure silver, the solution turns brilliant red, but when using sterling silver, it turns dark red. In addition, using low-quality coin silver promotes the solution to brown.

Conclusion

Potassium dichromate is usually handled with extreme caution and attention since it can be harmful to people if exposed for an extended period of time. It is obtained in an ionic solid crystalline condition and has a stunning vivid red-orange colour. When compared to other industrially significant salts like sodium dichromate, potassium dichromate’s non-deliquescent nature is the reason for its widespread application in analytical chemistry and industry.