Washing soda

Washing soda is sodium bi-carbonate decahydrate (Na2CO3.10H2O).
Manufacture

• It is manufactured by solvay process.
• The raw materials required are Ammonia(NH3), Limestone(CaCO3) and Brine solution (NaCl+H2O).
• Limestone is heated to produce quick lime(Calcium Oxide) and carbon dioxide
  CaCO3 --> CaO + CO2
• Water is added to quick lime to make it slaked lime
  CaO + H2O --> Ca(OH)2
• Slaked lime is passed through ammonium chloride to get calcium chloride, ammonia and Water
  Ca(OH)2 + 2 NH4Cl --> CaCl2 + 2NH3 + 2H2O
• Ammonia, Brine solution and carbon dioxide reacts to form baking soda and ammonium chloride
  NaCl + H2O + NH3 + CO2 --> NaHCO3 + NH4Cl
• Baking soda is heated to get soda ash, water and carbon dioxide
  2 NaHCO3 --> Na2CO3 + H2O + CO2
• Water is added to soda ash to get washing soda
  Na2CO3 + 10 H2O --> Na2CO3.10 H2O

Properties

• When exposed to air loses 9 molecules of water and forms sodium carbonate monohydrate
  Na2CO3.10 H2O --> Na2CO3.H2O + 9 H2O
  This property is called efflorescence.