Sodium carbonate is a white colored inorganic compound made up of sodium, carbon and oxygen elements. It has various hydrated forms. It has a strong alkaline taste.
Chemical Formula of Sodium Carbonate – Na2CO3
Its decahydrate form is called washing soda. Chemical formula of washing soda is Na2CO3.10H2O
Common Name of Sodium Carbonate – Sodium carbonate is the chemical name (or IUPAC name) of the compound Na2CO3. It is known by many common names also such as washing soda, soda ash, soda crystals.
Sodium carbonate is a basic salt. It tastes strongly alkaline. It is a salt of carbonic acid and sodium hydroxide. As it is made of weak acid (carbonic acid) and strong base (NaOH) so, it is strongly alkaline in nature. Reaction is given below –
H2CO3 + 2NaOH 🡪 Na2CO3 + 2H2O
Carbonic Sodium Sodium Water
Acid Hydroxide Carbonate
Its solution turns red litmus paper into blue which confirms its basic nature. Its pH is about 10.52.
Physical Properties :
Its molecular weight is 105.99 g/mol.
It is white crystalline solid which is soluble in water.
Its boiling point is 1600℃.
Its melting point is 851 ℃.
Its density is 2.54 g/cm3.
It is odorless.
Chemical Properties :
Reaction with dilute HCl –
Na2CO3 + 2HCl dil. 🡪 2NaCl + H2O + CO2
With water and carbon dioxide (preparation of sodium bicarbonate)–
Na2CO3 (saturated) + H2O + CO2 🡪 2NaHCO3
Reaction with hydrogen fluoride (diluted)
Na2CO3 + 2HF 🡪 2NaF + H2O + CO2
Each molecule of sodium carbonate contains 2 sodium atoms, one carbon atom and 3 oxygen atoms. It is an ionic compound which on dissociation gives two sodium cations (Na+) and one carbonate anion (CO3-2). Its structure is given below – Images to be uploaded soon.
Historically, sodium carbonate was extracted from the ashes of plants grown in sodium rich soil. Presently it is prepared by various methods such as Solvay process, Leblanc process, electrolytic process, Hou’s process etc. it is mined as well from several areas. The United States gets sodium carbonate mainly through mining which fulfils its domestic demand of sodium carbonate. Out of all these methods of preparation of sodium carbonate Solvay process is being used exclusively for the manufacture of sodium carbonate. So, we are describing the Solvay process here.
The Solvay process was discovered by Ernest Solvay, a Belgian industrial chemist, in 1861. It is more economical than other processes. It gives only calcium chloride as a waste product.
Solvay process is also known as ammonia-soda process. Brine solution, limestone and ammonia are used in the Solvay process which are inexpensive and easily available. Sodium chloride solution is called brine solution which provides sodium ions to produce sodium carbonate. Limestone is calcium carbonate which provides carbonate ions for sodium carbonate. Ammonia is an expensive ingredient in the production of sodium carbonate, but it is recovered in the process. 1st purification of saturated brine solution is done. Required carbon dioxide is prepared by heating limestone to 1300K. When it is dissolved in water it gives calcium hydroxide which is transferred into an ammonia recovery tower. Now carbon dioxide is passed through the brine solution which is saturated with ammonia to form sodium bicarbonate which is dried and ignited to form sodium carbonate. Reactions involved in the process are given below –
CaCO3 heat→ CaO + CO2
CaO + H2O 🡪 Ca(OH)2
2NH3 + H2O + CO2 🡪 (NH4)2CO3
(NH4)2CO3 + H2O + CO2 🡪 2NH4HCO3
2NH4HCO3 + NaCl 🡪 NaHCO3 + NH4Cl
NaHCO3 heat→ Na2CO3 + CO2 + H2O
Recovery of Ammonia –
NH4Cl + Ca(OH)2 🡪 2NH3 + CaCl2 + H2O
Few Uses of Sodium Carbonate are Listed Below –
It is largely used in production of detergents and soaps.
It is used in the manufacturing of glass.
It is used in the production of rayon polymers.
It is used in water softening.
It is used as a food additive as an anticaking agent, raising agent, stabilizer etc.
It is used in cooking for example ramen noodles get their authentic flavour due to sodium carbonate.
It is used as a laboratory reagent.
It is used in the brick industry.
It is used in processing and tanning of animal hides.
It is used in toothpaste where it acts as a foaming agent.
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