What is Sodium hydroxide? Describe the properties and uses of sodium hydroxide.

Sodium hydroxide

Sodium hydroxide or caustic soda is an inorganic compound with NaOH formula and is a white solid ionic compound that does not contain sodium cation Na+ and hydroxide anions OH−. It is a highly caustic base and alkali that decomposes proteins at normal ambient temperatures and can cause deadly chemical burns. It is highly soluble in water and easily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates NaOH.nH₂O. The monohydrate NaOH·H₂O crystallizes from a water solution between 12.3 and 61.8°C. Commercially available sodium hydroxide is often this monohydrate and published data may refer to it instead of anhydrous compounds. As a simple hydroxide, it is frequently used in neutral water and acidic hydrochloric acid and by chemistry students to demonstrate the pH scale.

History of Sodium hydroxide

Sodium hydroxide was first prepared by soap makers. The method of making sodium hydroxide appeared in an Arab book in the late thirteenth century as part of a recipe for making soap: Al-Mukhtara Fi Funun Min al-Suna, compiled by al-Muzaffar Yusuf ibn Umar ibn Ali ibn Rasul, King of Yemen. A solution of sodium hydroxide was obtained from a mixture of alkaline sodium carbonate and quicklime (calcium oxide, CaO) that was repeatedly called for the passage of water. European soap makers also followed this recipe. In 1791, when French chemist and surgeon Nicolas Leblanc patented a process of mass-producing sodium carbonate, the natural soda ash was replaced by this synthetic version. However, in the twentieth century, the electrolysis of sodium chloride became the primary method of producing sodium hydroxide.

Physical properties of Sodium hydroxide

1. Pure caustic soda or sodium hydroxide is a colorless crystalline solid.

2. Its melting point is 318°C and its boiling point is 1388°C.

3. Caustic soda is rapidly soluble in water.

4. It is less soluble in the polar solvent.

5. Sodium hydroxide is insoluble in ether and non-polar solvents.

6. The viscosity of caustic soda decreases when temperature increases and vice versa.

7. It may form different hydrates like NaOH.nH₂O.

8. It is odorless.

Chemical properties of sodium hydroxide

1. Sodium hydroxide reaction with acid produces salt and water.

NaOH (aq) + HCl (aq) = NaCl (aq) + H₂O (l)

2. It reacts with an acidic oxide such as SO₂,

2NaOH + SO₂ = Na₂SO₃ + H₂O

3. It reacts with iron and produces Ferric oxide, Sodium metal, and Hydrogen gas.

4Fe + 6NaOH = 2Fe₂O₃ + 6Na + 3H₂

4. Sodium hydroxide reacts with fat or oil and makes soap, this process is called saponification.

Synthesis or production procedure NaOH

Sodium hydroxide is industrially produced as 50% dissolved by the diversification of the electrolytic chloralkali process. In this process, Chlorine gas is also produced. After evaporation of water, solid sodium hydroxide is obtained from this solution. Solid sodium hydroxide is mostly sold like flakes, prills, and cast blocks.

Another process,

Sodium hydroxide was produced in a metastasis reaction using sodium carbonate with calcium hydroxide by a causticizing process.

Ca (OH) ₂ + Na₂CO₃ = CaCO₃ + 2NaOH

The process was unique in the late 19th century to the Solvay process, which today is surrounded by the chloralkali process that we use today.

It is also produced by direct sodium metal and water.

Uses of Sodium hydroxide

1. Sodium hydroxide is used in the textile industry as a popular strong base.

2. It is used in the manufacturing of sodium salt and detergent.

3. It is used in many situations where it is recommended to increase the alkalinity of a mixture or to neutralize the acid.

4. NaOH is used in the Bayer process of aluminum production.

5. It is used as a drill, mud mixer to increase alkalinity in the bentonite mud system, increase mud viscosity, and neutralize any acid gases that may be encountered in geological formations as well as increase insignificance.

6. It is used with hydrochloric acid to balance pH.

7. It is broadly used in the pulping of wood for making paper or regenerated fibers.

8. It is used to digest tissues.

9. It is used in the refining of alumina-containing ores to produce alumina.

10. It is used in the soap-making industry.

11. It is used as an industrial cleaning agent.

12. It is used in some cement mix plasticizers.