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What is Washing Soda?

What is Washing Soda?

Washing soda, also known as soda ash, is sodium carbonate. It is a colorless and odorless crystalline solid. This article tells you about its sources, methods of production, and uses.
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Washing soda is a sodium salt of carbonic acid. It is sodium carbonate, also known as soda ash. Washing soda is largely used for the production of glass. It is used to regulate pH for maintaining stable alkaline conditions. It finds applications in chemistry, where it is used as an electrolyte. It is known as washing soda, probably because it can remove oil and alcohol stains. That's the reason it is used as a softener during laundry.

Chemical Formula: Na2CO3
Molecular Weight: 105.9 g/mol
Properties: It is soluble in water and hygroscopic in nature. It occurs in the form of crystals and appears white/colorless.

Sources of Washing Soda
Sodium carbonate occurs naturally in arid regions. It is found in the form of deposits on locations where lakes evaporate. It is believed to have erupted from volcanoes. The sodium carbonate that is mined from different parts of the United States is a major source of washing soda. Certain salt-tolerant plant species can be used for the production of an impure form of washing soda. Washing soda occurs as a heptahydrate of a crystalline nature, which on losing its water of crystallization forms a monohydrate.

Methods of Production

Solvay Process
Calcium carbonate is heated to release carbon dioxide. When carbon dioxide is bubbled through a concentrated solution of sodium chloride and ammonia, sodium bicarbonate precipitates, while also producing ammonium chloride. Heating of sodium bicarbonate produces sodium carbonate or washing soda. The ammonium chloride produced in the previous reaction is treated with lime to regenerate ammonia. The replenishment of ammonia brought about through the Solvay process makes it more economical as compared to other methods of producing washing soda.

Hou's Process
This process is similar to the Solvay process. However, the last step is replaced by a process of pumping carbon dioxide and ammonia into the ammonium chloride solution and adding common salt to it. The solution is saturated at 40 degrees Celsius and cooled to 10 degrees. It is recycled to generate sodium carbonate.

Washing soda is an important constituent of most detergents and washing powders. Do not confuse it with baking soda. The former is a carbonate of sodium, while the latter is its bicarbonate.