Describe how washing soda is produced from sodium chloride
Answers
Answer:
Washing Soda is sodium carbonate containing 10 molecules of water of crystallisation. So, we can say that washing soda is sodium carbonate decahydrate (Na2CO3.10H2O).
The sodium carbonate which does not contain any water of crystallisation is called anhydrous sodium carbonate or soda ash (Na2CO3).
How Washing Soda is produced?
In the following three steps, washing soda is prepared from sodium chloride or common salt.
Firstly, a cold and concentrated sodium chloride solution is reacted with ammonia and carbon dioxide to obtain sodium hydrogen carbonate.
The sodium hydrogen carbonate is slightly soluble in water, so it precipitates out as solid.
NaCl +NH3 +CO2 +H2O → NaHCO3 +NH4Cl
Secondly, now sodium hydrogen carbonate is separated by filtration, dried and heated. On heating sodium hydrogen carbonate decomposes to form sodium carbonate. This anhydrous sodium carbonate is known as soda ash.
2NaHCO3 → Na2CO3 +H2O +CO2
Soda ash
The preparation of Sodium Carbonate is also known as Solvay process. But before that calcium carbonate (limestone) was heated to release carbon dioxide.