Soapy Facts

     Have you ever wondered where does soap comes from and what does it made of? Well, soap is a chemical substance that used as a cleansing agent to remove grease and dirt. Or a more scientific definition, soap is sodium or potassium salts of long chain fatty acids. Soap is categorized as a cosmetics product because cosmetic is defined as a substance in contact with any external part of our body such as skin, mouth, face and etc.

     The use of soap is not a modern phenomenon as it was recorded that the soap was made by the Babylonians around 2800 B.C. Ancient Egyptians used ashes of plants which contain sodium carbonate and potassium carbonate to make soaps by boiling it with lime (calcium oxide) to produce caustic potash, which is also known as potassium hydroxide. This caustic potash was then boiled with animal fats such as tallow to produce soaps. Examples of soaps that are commonly used are sodium palmitate, sodium oleate and sodium stearate.

     Nowadays, soaps can be manufactured easily by using the reaction between salts and animal fats or vegetable oils which is known as saponification. Now you must be asking yourself what is saponification right? Saponification is actually a process of alkaline hydrolysis of esters using alkali solution. Using this process, animal fats or vegetable oils are boiled with concentrated alkalis which it will then break down the ester molecules into soap and glycerol.

     Now, let us take a look at how does the soap works in the cleansing action of a cloth with dirt or grease. As we know that soap consists of a negatively charged ‘ head’ which is soluble in water and a long fatty acids ‘tail’ which is soluble in oil, thus, this action is depends on the structures and the chemical bonding of the soap. When the soap is mixed with water, the ionic ‘head’ will be dissolved in water whereas the fatty acids ‘tail’ will be dissolved in the grease or dirt. The water is then being slightly agitated to lift up the grease from the cloth’s surface. Since grease is less dense than water, the grease will be lifted up. The grease can also be emulsified into smaller droplets by shaking the water to break the grease. The smaller droplets will not rejoined as they all have the same charge and thus they repel each other and can be easily removed by rinsing the cloth with water.

     Although in this modern era, most people prefer to use detergents instead of soaps, but soaps are actually biodegradable which means that it does not cause pollutions to the environment. The explanation is that soaps are made of animal fats and vegetable oils whereas detergents are mostly made of petrochemicals which contain branched hydrocarbon chains that make it a non-biodegradable substance.

     So, next time when you want to buy soaps, you know which one is best for you and the environment.