ANS:C - Sodium stearate

Sodium stearate is a type of salt derived from stearic acid, a saturated fatty acid commonly found in animal and vegetable fats. It is also known as sodium octadecanoate. Sodium stearate is a white, waxy solid at room temperature and is commonly used in various industrial and consumer applications. Here are some key points about sodium stearate:

1. Chemical Structure: Sodium stearate has the chemical formula C18H35NaO2. It is composed of a long hydrocarbon chain (18 carbon atoms) with a carboxylate group at one end and a sodium ion attached to it, giving it a negative charge.
2. Hydrophobic and Hydrophilic Properties: Sodium stearate is an amphiphilic molecule, meaning it has both hydrophobic (water-repellent) and hydrophilic (water-attracting) properties. The long hydrocarbon chain is hydrophobic, while the carboxylate group is hydrophilic.
3. Surfactant Properties: Due to its amphiphilic nature, sodium stearate acts as a surfactant, meaning it can reduce surface tension and promote the dispersion of substances in water. This property makes it useful in various applications such as emulsification, dispersion, and as a foaming agent.
4. Lubricant and Emulsifier: Sodium stearate is commonly used as a lubricant in industrial processes, including metalworking (such as wire drawing) and pharmaceutical manufacturing. It reduces friction between surfaces and helps facilitate smooth movement. Additionally, sodium stearate is used as an emulsifier in the production of cosmetics, personal care products, and food items to stabilize oil-in-water emulsions.
5. Soap Formation: Sodium stearate is a key ingredient in soap-making processes. When stearic acid reacts with sodium hydroxide (lye) in a process called saponification, sodium stearate is formed along with glycerin. This reaction produces soap, which has cleansing properties due to its ability to dissolve oils and dirt in water.

Overall, sodium stearate is a versatile compound with various industrial and commercial applications, primarily as a lubricant, emulsifier, and surfactant. Its amphiphilic nature and ability to reduce friction make it valuable in numerous processes and products.