We will study here about the preparation, properties and uses of Sodium Carbonate. Chemical formula of washing soda is Na2CO3.10H2O
Preparation of Sodium Carbonate
In Solvay Ammonia Process firstly, CO2 is passed through brine solution saturated with NH3
NH3 + H2O ……………………..> NH4+ + OH-
Na+ + Cl- + NH4+ + OH- + CO2 ……………………> Na+ + HCO3- + NH4+ + Cl-
Na+ + HCO3- ……………………………> NaHCO3 ( precipitate )
NH4+ + Cl- ………………………………….> NH4Cl ( solution )
NaHCO3 + heat ……………………………> Na2CO3 + CO2 + H2O
Finally, Na2CO3 formed , filtered and heated which gives pure Na2CO3. Recrystalization from water produces Na2CO3.10H2O.
Na2CO3 ( Sodium Carbonate ) + 10H2O………………….> Na2CO3.10H2O ( Washing Soda )
Function of Ammonia in Washing Soda Preparation
Carbon dioxide is an acidic oxide which reacts with water to form Carbonic acid.
CO2 + H2O …………………..> H2CO3
H2CO3 ………………………..> H+ + HCO3-
NH3 combines with H+ to form NH4+. This shifts the equilibrium in the forward direction.
Properties of Washing Soda
- Sodium Carbonate is a white crystalline solid ( Na2CO3.10H2O decahydrate crystals )
- Washing Soda is readily soluble in water.
- On heating Sodium carbonate decahydrate loses water of crystallisation.
Na2CO3.10H2O + temp below 373K………………..> Na2CO3.H2O + 9H2O
Na2CO3.H2O + temp above 373K ………………………> Na2CO3 + H2O
4. Sodium Carbonate reacts with HCl to form salt, water and CO2
Na2CO3 + HCl …………………..> NaCl + H2O + CO2
5. Carbonic acid and Sodium hydroxide reacts to form Sodium Carbonate. Therefore, Na2CO3 dissolves in H2O to form alkaline solution.
Na2CO3 + 2H2O …………………….> H2CO3 (Weak acid ) + 2NaOH (Strong base )
6. Sodium Carbonate reacts with milk of lime Ca(OH)2 reacts to form CaCO3 and NaOH
Ca(OH)2 + Na2CO3 ……………> CaCO3 + NaOH
Uses of sodium carbonate, washing soda
- Washing soda is used in the manufacturing of soap, class, Caustic soda, sodium phosphate, borax and many more substances
- Sodium carbonate is used in paper in textile industry and in petroleum, refining and metal refining industries.
- Washing soda is used for softening of hard water, laundry and cleaning.
- Na2CO3 is used as an important Regent in the laboratory.
- Washing soda is used in paints and dyes.
FAQs related to sodium carbonate, washing Soda
- Why is washing soda called basic in nature?
Answer : Washing soda is a basic salt. Therefore, it is dissolved in water to give H2CO3 which is a weak acid. But washing soda dissolves in water to give NaOH which is a strong base.
2. What is the pH of washing soda?
Answer : Washing soda is highly alkaline with a pH of 11
3. Is washing soda used as disinfectant?
Answer : Because Na2CO3 has the ability to soften water and remove grease.
Check out the structure of NH3 here
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