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How does Soap Work?

Anju Shandilya
Read this story to know more about the chemical details of soap, and how it actually works.
Soap is a cleansing agent, and is made from the interaction of fats and oils with alkalis. Records mention the use of these healthcare products ancient times. Soap making was common in Italy and Spain during the 8th century, and by the end of the 13th century, soaps were freely available in France.
In 1783, a Swedish chemist accidentally simulated the reaction that occurs in the present-day boiling process of soap making. He produced a sweet-tasting substance that is now known as glycerin. In 1823, a French chemist discovered the chemical nature of the ingredients used in soap.
These agents are mixtures of sodium or potassium salts of fatty acids, which can be produced from oils or fats by reacting them with an alkali at 80°-100 °C, in a process known as saponification.
Each soap molecule has a long hydrocarbon chain, sometimes called its 'tail', with a carboxylate 'head'. In water, the sodium or potassium ions float free, leaving a negatively charged head.

Working of Soap
Soap is an excellent cleanser because of its ability to act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another immiscible liquid. Nearly all chemical compounds fall into two categories: hydrophilic and hydrophobic. Water and any substance that will mix with it are hydrophilic.
Oil and any substance that will mix with it are hydrophobic. When water and oil are mixed they get separated, which is why hydrophilic and hydrophobic compounds cannot form a mixture. When grease or oil is mixed with a soap-water solution, the soap molecules work as a bridge between polar water molecules and non-polar oil molecules.
Since soap molecules have both the properties of non-polar and polar molecules, soap will form micelles and trap the fats within them. Since the micelle is soluble in water, it can easily be washed away. A good hosing down with plain water with a little rubbing will do a reasonable job of removing the dirt.
Soap is not really necessary for the job. However if the dirt particles have a slightly oily coating, then they will stick to your skin like wet mud. Your skin also has enough oil on it to make the dirt particles stick.
But unlike the mud, this dirt is going to stay stuck because oil doesn't evaporate, and dry up as water does. To remove the oil adhering dirt, is to seek out and destroy the sticky oil itself. A liquid can then be applied, and the dirt will fall off and be swept away.
One should always be careful while applying any soap or solvent to an open wound, as the soap ingredients might worsen the reaction. The soaps that do not contain harmful chemicals also might react with the skin.
The wide range of toilet soaps is made up of natural, as well as synthetic essential oils. These products are soft to the touch and give out a pleasant fragrance.
Different varieties of such healthcare products available in the market are herbal soaps, antibacterial soaps, medicated soaps, moisturizing soaps, and toilet soaps.