Potassium carbonate is an inorganic compound that is made up of potassium, carbon and oxygen. By definition, carbonate is any compound containing the polyatomic carbonate anion made up of carbon and oxygen and represented as CO32-. Also, potassium is very well known for having the capacity to lose one electron in order to gain a stable octet electronic configuration in the valence shell. Thus, a neutral chemical formula of potassium carbonate will contain two potassium cations and one carbonate anion. Hence, the chemical formula of potassium carbonate is given as K2CO3. Potassium carbonate is also known as pearl ash and hence the pearl ash formula is the same as potassium carbonate formula.
General Physical Properties of Potassium Carbonate
Potassium carbonate is a white salt which when dissolved in water dissociates into its constituents of potassium cations and carbonate anions as shown by the potassium carbonate formula. It has the capability to retain water molecules and due to this reason, it often appears as a damp or a wet solid. The structural formula of potassium carbonate showing its constituent ions, as depicted by the potassium carbonate formula, is given below:
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Typical physical properties of potassium carbonate such as molar mass density, etc. are given below:
The molar mass of potassium carbonate as can be calculated from the formula of potassium carbonate is 138.21 g/mol.
The density of the compound is 2.43 g/cm3.
It has already been mentioned that it is a white hygroscopic solid i.e. has the capacity to retain water molecules.
The melting point is 891℃. It does not have any boiling point as it decomposes on heating at extreme temperatures.
Along with being soluble in water, it is soluble in methanol solution and insoluble in a solution of alcohol and acetone.
It is a non-flammable compound just like potassium sulphate.
Production of Potassium Sulphate
The commercial production of potassium sulphate is carried out by the reaction between potassium hydroxide and carbon dioxide. The stoichiometrically balanced equation for the reaction with the molecular formula of potassium carbonate and other compounds is given below:
2KOH + CO2 → K2CO3 + H2O
Another method of production of potassium carbonate is similar to the production of potassium sulphate. In this method, potassium chloride is made to react with carbon dioxide in the presence of an organic amine compound which gives potassium bicarbonate as a product. This potassium bicarbonate on reduction gives potassium carbonate, water and carbon dioxide. The balanced chemical equation representing the formula of potassium carbonate and other compounds is as follows:
2KHCO3 → K2CO3 + H2O + CO2
Use of Potassium Carbonate
The most commonly known use of potassium carbonate has been for the manufacturing of soap, glass and china material. It has also been used as a mild drying agent in cases where other drying agents such as calcium chloride and magnesium sulfate. It has been historically also used as an ingredient in the production of grass jelly, in Chinese and Southeast Asian cuisines such as Chinese hand-pulled noodles and moon cake and in recipes such as German gingerbread.
It has been used in the alkalization of cocoa powder for the manufacturing of Dutch-process chocolate by balancing the pH of the cocoa beans. It is also used for enhancing the aroma of cocoa beans and for buffering during the production of mead or wine. It is used in antique documents and hence has been used for softening of hard water.
Some other common applications of potassium carbonate include fire suppressant in extinguishing deep-fat fryers, condensed aerosol fire suppression, as an ingredient in welding fluxes, as an animal feed ingredient for the satisfaction of potassium requirements and as an acidity regulator in Swedish snus.