MCQ Detailed View

Caustic soda, chemically known as sodium hydroxide (NaOH), is a strong base and one of the most widely used chemicals in industry. It is highly caustic, meaning it can dissolve grease, oils, and many organic materials. Because of this property, NaOH is a key raw material in several chemical manufacturing processes.

One of the most important uses of caustic soda is in the production of soap. The process through which soap is made is called saponification. In this reaction, fats or oils (which are esters of fatty acids and glycerol) are heated with caustic soda. The alkali breaks down the ester bonds, producing glycerol and the sodium salts of fatty acids, which are soaps. This reaction can be summarized as:

$$Fat/Oil+NaOH\to Glycerol+Soap(sodiumsaltoffattyacid)$$

Soap made from caustic soda is usually hard soap, while softer soaps can be made using potassium hydroxide (KOH). Hard soaps are common in households and industries because they have strong cleansing power.

Although caustic soda also has applications in making detergents, paper, textiles, and cleaning agents, its primary and most extensive use is in soap manufacturing. The production of Plaster of Paris (CaSO₄·½H₂O) does not involve NaOH, and gum production also does not require it. Detergents may involve sodium hydroxide indirectly, but surfactants are synthesized differently.

Because of its strong alkaline properties, NaOH is also used in water treatment, petroleum refining, textile processing, and chemical synthesis. However, its major association remains with soap manufacturing, making option B (Soap) the correct answer.