Some Important Compounds of Sodium

Sodium is an alkali metal of group 1. The atomic number of sodium is 11. It is a soft, white, highly reactive alkali metal. It has one electron in the outermost shell, on losing it, it forms a sodium ion.  Sodium do not occur free in nature as it is highly reactive. It is kept in kerosene oil to prevent its reaction in the atmosphere. It has mainly three minerals such as sodalite, feldspar, and rock salt. Rock salt is commonly known as Sodium Chloride (NaCl).
 

Properties of Sodium

• It is highly reactive alkali metal.

• It is soft, can be easily cut with knife.

• The melting and boiling point of sodium is lower than that of lithium.

• It possesses metallic bonding. It is also conducting in nature as it has one free electron.

• It appears yellow in flame test.

• It has lower first ionization energy.

• The common oxidation state of sodium atom is +1.
   

Uses of Sodium

• Sodium ions are primarily found outside the human cells such as nerve cells

• They regulate the flow of water across the membrane

• They are needed for transport of sugars and amino acids into the cells.
   

Important Compounds of Sodium are as Follows-

The most important compounds of sodium that are of commercial importance are as follows-

Sodium Carbonate

• It is commonly known as Washing Soda with molecular formula Na₂CO_3.10H₂O.

Fig. 1. Structure of sodium carbonate

• It is synthesized by Solvay process. During this process, sodium carbonate is synthesized using sodium chloride and calcium carbonate.

2 NaCl + CaCO₃→ Na₂CO₃+ CaCl₂

The steps for the formation of:

1. During first step, sodium chloride reacts with ammonia, carbon-dioxide and water to form sodium bi-carbonate.

NaCl + CO₂ + NH₃ + H₂O → NaHCO₃ + NH₄Cl

2. During the second step, calcium carbonate is converted into calcium oxide and calcium carbonate.

CaCO₃ → CO₂ + CaO

3. Sodium bicarbonate reacts with calcium oxide from the step 2 to form ammonia, calcium chloride and water

2 NH₄Cl + CaO → 2 NH₃ + CaCl₂ + H₂O

4. Sodium bicarbonate finally decompose into sodium carbonate.

2 NaHCO₃ → Na₂CO₃ + H₂O + CO₂

• Sodium carbonate is readily soluble in water.

• Heating of sodium carbonate decahydrate leads to the formation of sodium carbonate monohydrate. On further heating, monohydrate is converted into anhydrous form of sodium carbonate (without water).

Uses of Sodium Carbonate:

• Used in water softening, cleaning and laundering.

• Used in manufacturing of glass, borax, soap, and caustic soda.

• It is also used in paint and textiles industry.

• It plays an important role during qualitative and quantitative analysis in the laboratory.
   

Sodium Chloride (NaCl)

• The main source of sodium chloride is sea water.

• Evaporation of sea water is the most common method to obtain sodium chloride.

• Crude sodium chloride is obtained by crystallization of brine solution, containing sodium sulphate, calcium sulphate, calcium chloride and magnesium chloride.

• To obtain pure sodium chloride, crude salt is dissolved in water and filtered to remove impurities.

Fig. 2. Structure of crystal of sodium chloride 

Uses of Sodium chloride

• It is used as common salt for domestic purpose.

• It is used for the preparation of Na₂O₂, NaOH and Na₂CO₃.
   

Sodium Hydroxide (NaOH)

• Also known as Caustic Soda.

• The process of formation of sodium hydroxide is known as Castner-Kellner Cell. 

Fig. 3. Castner-Kellner cell

Electrolysis of sodium chloride forms sodium hydroxide. During electrolysis reaction, mercury is used as cathode and carbon as anode. Sodium combines with mercury to form sodium amalgam at the cathode. Chlorine gas is evolved at anode.

• Sodium hydroxide is a white solid which is soluble in water.

• Sodium hydroxide crystals are deliquescent.

• Sodium hydroxide reacts with carbon-dioxide to form Na₂CO₃.

Uses of Sodium Hydroxide

• It is used in the manufacturing of soap, paper, artificial silk etc.

• Its use has been observed during petroleum refining.

• It is used in textiles industries such as cotton industries.

• It is used as a precipitating agent in the laboratories.

• Another use of sodium hydroxide is during preparation of fats and oils.
   

Sodium Hydrogen Carbonate

• It is also known as Baking Soda with a molecular formula, NaHCO₃.

• Its decomposition forms carbon-dioxide.

2 NaHCO₃(s)  CO₂(g) + H₂O(g) + Na₂CO₃(s)

Fig. 5. Structure of sodium hydrogen carbonate

• Sodium carbonate and carbon-dioxide forms sodium hydrogen carbonate.

• It is used as an antiseptic during skin infections.

• It is also used as a fire extinguisher.

• It is used in bakeries to prepare pastries, cake etc.

Watch this Video for more reference
 

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Imporatnt Compounds of Sodium