↪ Molecular formula: Na2CO3.10H2O
↪ Chemical name: Sodium Carbonate
|Common Names||Molecular Formulae|
|Light Soda ash||Na2CO3|
|Baking soda||NaHCO3 |
↪ It is the most important carbonate of metal.
↪ It occurs as anhydrous form, Na2CO3 which is called light soda ash since it is a fluffy solid with low packing density.
↪ Monohydrate form of sodium carbonate (Na2CO3.H2O) is called heavy ash.
↪ Its heptahydrate form, (Na2CO3.7H2O) also exists.
↪ Its decahydrate form, (Na2CO3.10H2O), is white crystalline solid and is called washing soda.
↪ It occurs in nature as "trona" (Na2CO3.NaHCO3.2H2O) which gives sodium carbonate on heating.
⁕ Physical Properties
- It is crystalline solid.
- It is soluble in water.
- It is efflorescent and it loses nine molecules of water when it is heated up to 100°C and above 100°C it loses all molecules of water and becomes anhydrous.
- Anhydrous sodium carbonate melts at 852.1°C.
⁕ Chemical Properties
- Action with water
↪ Sodium carbonate dissolves in water to give carbonic acid and caustic soda.
- Action with acids
↪ It reacts with acids to give salt, water and carbon dioxide.
- Precipitation Reaction
↪ Sodium carbonate reacts with some metallic salt solution to give precipitate of their carbonate.
- Action with Sulphur Dioxide
↪ Sodium carbonate reacts with Sulphur dioxide sodium sulphite and CO2.
↪ But in presence of Sulphur it gives sodium thiosulphate
- Action with lime water
↪ On boiling with lime water, it produces caustic soda and calcium carbonate.
- Action with CO2
↪ When CO2 gas is passed in the aqueous solution of Na2CO3, it forms insoluble sodium bicarbonate (NaHCO3).
- Action with silica (sand)
↪ When Na2CO3 is heated with silica, sodium silicate is formed.
⁕ Uses of Sodium Carbonate
- It is used in paper, paints and textile industries.
- It is used in washing propose in laundry.
- It is used in the manufacture of glass, borax, soap, hypo etc.
- It is used as laboratory reagent.
- It is used for softening of hard water.