Sodium Carbonate

Soda ash is a generic term for sodium carbonate. It is made from Trona. Trona has two salt solutions which are sodium carbonate and sodium hydrogen carbonate. Sodium carbonate is a basic salt that contains sodium hydroxide and carbonic acid, carbonic acid is a weak acid, and sodium hydroxide is a strong base; it is alkaline. It is a white powder with no odour. It has a cool alkaline taste and can be extracted from the ashes of various plants. It is also produced artificially in large amounts from common salt. Since it has a strong base, it can be used as an antacid. 

How is Sodium Carbonate Extracted? 

Sodium carbonate can be extracted in four different ways:

• Solvay process, 
• Leblanc process, 
• Dual-process, and 
• Electrolysis.

Solvay Process

The Solvay process is formerly known as the ammonia-soda process. It is used majorly in the industrial sector for the production of sodium carbonate. The key reaction involved in this process is, 

NaCl + NH3 + CO2 +H2O → NaHCO3(s) + NH4Cl

Here the sodium chloride solution is saturated with ammonia. With the help of carbon dioxide, it is cooled. It is a precipitation reaction where we get solid sodium bicarbonate in solution. When it is heated, the solid sodium bicarbonate changes to sodium carbonate, water vapour and carbon dioxide gas.

2NaHCO3 + heat→Na2CO3 + H2O(g) + CO2(g)

Here the carbon dioxide gas, which is released, is used back in the initial step. It is done like that, so there is no wastage. It is an inexpensive procedure, as the raw materials are available easily in the form of limestone and sodium chloride. A certain amount of ammonia is required to initiate the process but then small quantities to keep it going. It also maximises the usage of two reactants, ammonia and carbon dioxide. 

The calcination of limestone provides a lot of carbon dioxide to make up the losses in the process, but some ammonia needs to be added to compensate for any leakage. To know about other processes, refer to this study material on sodium carbonate. 

Leblanc Process 

It was used throughout the 19th century for the production of sodium carbonate. It involves two stages: production of sodium sulphate from sodium chloride and then sodium sulphate reacting with coal and calcium carbonate to get sodium carbonate. 

This process involves producing sodium carbonate from salt, sulfuric acid, limestone and coal. 

Firstly, the sodium chloride is boiled with sulfuric acid to get sodium sulphate and hydrogen chloride gas.

2NaCl + H2SO4 → Na2SO4 + 2 HCl

Secondly, the sodium sulphate is blended with powdered limestone and coal; the mixture is burned to produce sodium carbonate along with carbon dioxide and calcium sulphide. 

Na2SO4 + CaCO3 + 2C → Na2CO3 + 2CO2 + CaS

The sodium carbonate obtained is mixed with ashes, so it is mixed with water, and then the water is evaporated.

Dual-Process

In the dual-process, ammonia is absorbed by sodium bicarbonate, and sodium chloride is added. When cooled, ammonium chloride is separated and dried in rotary dryers with air. Sodium bicarbonate is recycled and precipitated; finally, we obtain sodium carbonate.

Electrolysis

In electrolysis, an aqueous form of sodium bicarbonate is added. Hydrogen is attracted to the cathode, and sodium carbonate is attracted to the anode.

Uses of Sodium Carbonate

Sodium carbonate is used in various aspects of our daily lives. 

• Helps in the production of detergents and soaps. 
• Manufacturing of glass.
• Production of rayon polymers. 
• Food additives such as anticaking agents, raising agents, etc. 
• Processing and tanning of animal hides. 
• Modification of pH of water.
• Acts as a laboratory standardisation reagent. 

Chemical and Physical Properties 

Sodium carbonate’s physical properties are:

• The molecular mass of sodium carbonate is 105.99 g/mol. 
• It is a white crystalline substance. 
• Highly soluble in water.
• It is odourless.

Chemical properties are:

• Anhydrous sodium carbonate( there is no water in it) is unaffected by heat. 
• The release of OH ions during hydrolysis makes sodium carbonate alkaline. 
• The carbon dioxide present in the air is absorbed by aqueous sodium carbonate and produces sodium hydrogen carbonate. 
• Carbon dioxide is formed when sodium carbonate reacts with lime juice or any vegetable juice. 

Where is Sodium Carbonate Found?

Sodium carbonate is water-soluble and can be naturally found in dry areas, especially in areas where mineral deposits are formed when lakes evaporate. It is found mainly in alkali lakes and volcanoes. Alkali lakes have a high amount of sodium carbonate. There are approximately one million tonnes of anhydrous sulphate. It has a small amount of borax in lakes all across the world. Volcanoes have an anhydrous form of sodium carbonate. 

Can You Drink Water with Sodium Carbonate?

Sodium carbonate is dangerous as it is a highly concentrated solution. Household cleaning does include 10%  sodium carbonate in it. If brought in contact with the skin for a long time, it can irritate the skin. It can cause dermatitis and even burns. Ingestion of concentrated salt can result in nausea, vomiting, stomach ache, diarrhoea, mouth and throat burns. It is present in carbonated drinks, but it only has 10% or less, which is for consumption. 

Conclusion

In a nutshell, sodium carbonate is used as a neutralising agent. It is hazardous for our health when consumed in large quantities. Our body can accept only up to 10% of sodium carbonate in any form. Even though sodium carbonate is non-corrosive and safer to handle than sodium hydroxide, you should be careful while using it. Since it is strongly alkaline, they are inorganic chemicals and cannot degrade.