The Solvay process is used to manufacture sodium carbonate Na2CO3.

The steps involved in this process are:

1. Purify saturated brine

2. React it with gaseous ammonia

3. The ammoniated brine is carbonated with CO2 to form NaHCO3

4. This is insoluble in brine solution, so can be filtered out.

5. On heating, it decomposes to Na2CO3

6. CaCO3 is also used to provide CO2


Reactions: 1. CO2 reacts with ammonia to form ammonium carbonate.

2NH3 + CO2 + H2O --> (NH4)2CO3

2.Ammonium carbonate further reacts with CO2 to form ammonium bicarbonate.

(NH4)2CO3 + CO2 + H2O --> 2NH4HCO3 (aq.)

3. Ammonium bicarbonate then react with NaCl to form sodium bicarbonate.

NH4HCO3 + NaCl --> NaHCO3 + NH4Cl

Due to exothermic nature of above reactions, solubility of NaHCO3 increases. To counter this effect , the solution is cooled, precipitate of NaHCO3 are separated by vacuum filtration and washed to remove ammonium salts.

4.Dry sodium bicarbonate is then heated to give anhydrous sodium carbonate. Carbon dioxide is then again recirculated.

2NaHCO3 --> Na2CO3 + CO2 + H2O


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The Solvay ammonia process is a method used for the manufacture of sodium carbonate (Na2CO3), commonly known as soda ash. This process involves several chemical reactions and steps that allow for the production of sodium carbonate in large quantities.

1. Introduction
The Solvay ammonia process was developed in the 19th century by Ernest Solvay, a Belgian chemist. This process revolutionized the production of sodium carbonate and became the primary method used worldwide for its manufacture.

2. Raw Materials
The main raw materials required for the Solvay ammonia process are:

- Brine (sodium chloride solution)
- Ammonia gas (NH3)
- Limestone (calcium carbonate - CaCO3)

3. Carbonation
The first step in the process involves the carbonation of brine. Brine is heated and then saturated with ammonia gas, forming a solution known as ammoniated brine. This ammoniated brine is then reacted with carbon dioxide (CO2) gas in large containers called carbonation towers. The reaction between ammoniated brine and carbon dioxide produces sodium bicarbonate (NaHCO3) and ammonium chloride (NH4Cl).

4. Sodium Bicarbonate Separation
In this step, the ammonium chloride and sodium bicarbonate mixture is separated. The mixture is centrifuged to remove the solid sodium bicarbonate, which is then washed and dried. The remaining liquid, containing ammonium chloride, is sent back to the carbonation tower for recycling.

5. Conversion to Sodium Carbonate
The obtained sodium bicarbonate is then heated in a rotary kiln. This heating process decomposes sodium bicarbonate into sodium carbonate, water vapor, and carbon dioxide. The chemical reaction can be represented as follows:

2 NaHCO3 → Na2CO3 + H2O + CO2

6. Recovery
After the conversion to sodium carbonate, the mixture is cooled and then sent to a series of purification steps to remove impurities. The final product is obtained as a white crystalline powder of sodium carbonate.

7. Byproduct Utilization
Throughout the Solvay ammonia process, several byproducts are generated. For example, the ammonia gas used in the process is recovered and reused. Additionally, the leftover calcium oxide (CaO) from the limestone can be converted back to calcium carbonate through carbonation and then used again in the process.

Conclusion
The Solvay ammonia process is an efficient and widely adopted method for the large-scale production of sodium carbonate. It involves the carbonation of brine, separation of sodium bicarbonate, conversion to sodium carbonate, purification, and recovery of byproducts. This process has played a significant role in meeting the global demand for sodium carbonate, which is used in various industries such as glass manufacturing, paper production, and water treatment.