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Question
In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH4Cl with Ca(OH)2. The by-product obtained in this process is ______.
Options
CaCl2
NaCl
NaOH
NaHCO3
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Solution
In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH4Cl with Ca(OH)2. The by-product obtained in this process is CaCl2.
Explanation:
Sodium carbonate is synthesised by Solvay or ammonia soda process. The reactions involved are
\[\ce{NH3 + H2O + CO2 -> \underset{Ammonium bicarbonate}{NH4HCO3}}\]
\[\ce{NaCl + NH4HCO3 -> \underset{Sodium bicarbonate}{NaHCO3} ↓ + NH4Cl}\]
\[\ce{2NaHCO3 ->[Δ] \underset{Sodium carbonate}{Na2CO3} + H2O +CO2 }\]
NH3 is recovered from NH4HCO3 and NH4Cl formed during the reaction.
\[\ce{NH4HCO3 ->[Heat] NH3 + H2O + CO2}\]
\[\ce{\underset{Ammonium chloride}{2NH4Cl} + Ca(OH)2 -> \underset{Ammonia}{2NH3} + \underset{Calcium chloride}{CaCl2} + H2O}\]
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