What is soap? How is soap made?
Generally, soap is a surfactant which is used in daily life for cleaning or washing away the dirt. The soap is produced through a process called saponification. Saponification is a chemical process where the sodium hydroxide or potassium hydroxide is used to mixed with the animal fat or vegetablee oil to produced soap and glycerol. In other word, saponification is a process of mixing the fatty acids, either is animal fats or vegetable oils with the alkaline solution or lye to produce the soap (alkali salt with fatty acid) and glycerol. The picture below has illustrated the equation on how the soap is formed:
How is soap function?
Since that most of the dirt are grease and oil, they are unable to dissolve in the water. Thus, here comes the role of soap which act as an emulsify agent to dissolve and wash away the grease and oil along with the water. Do you see people washing something using soap without water? Soap cannot play with single role, hence it must have the water in order to reveal its true function. Well, the unique structure of the soap has plays the main role of dissolving the grease and oils. A soap molecule is made up of both hydrophilic head and hydrophobic tail. Hydrophilic head is able to dissolve the polar molecules, such as water while the hydrophobic tail is able to dissolve the non-polar molecules, such as the oils.
The diagram below shows the structure of the soap molecule:
Due to the unique structure, the soap molecule will form a circular-liked shape, which is also known as the micelles. So how do the micelles form? As I mentioned before, we are washing with both the water and soap, which means that the water molecule are presence surrounding the grease. So, the micelles is formed when the hydrophilic heads of the soap molecules are attracted to the water molecules while the hydrophobic tails of the soap molecules are attracted to the grease. Therefore, the hydrophilic heads will face outward with the water molecules while the hydrophobic tails will face inward with the grease. As a result, it formed the micelles whereby the grease is trapped inside of it and will be washed away by the water as shown the the diagram below.
Advantages and disadvantages of soap
There are few advantages and disadvantages of soap. The advantages of soap are:
- It is the cheapest among the other surfactants.
- It is biodegradable since it is made of natural fats and oils.
- It will not cause any water pollution.
- Some anti-bacterial soap can remove the bacteria and excessive microflora on the skin to maintain skin health.
- It might not as efficiency as other surfactants in removing the dirt.
- It might remove the natural oils in our skin as well.
- It will also damage the fabric of clothes.
- It will form percipitate or scum if react with the lime in hard water, which is the water that contain high mineral ions such as calcium and magnesium ions.
- It will also damage the proteins in our hair.
Should use or should not use the soap?
There are some tips of using the soap, either you should use or should not use, which are:
- Use the soap which has additional oil in order to replace the natural oil that had lost on your skin.
- Use the soap which has the anti-bacterial properties so that it can kill the bacteria on your skin.
- Use detergent instead of soap to wash your dishes because detergent is more effective in cleaning and removing the dirt on your dishes.
- Use detergent instead of soap when washing in hard water because detergent will not form any percipitate or scum in hard water.
- Use washing powder instead of soap to wash your clothes because the soap will damage the fabric of your clothes.
- Use shampoo instead of soap to wash your hair since the soap will damage the protein in your hair.
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