We use soap each day in our lives in form of detergents, shampoo, shower crème, hand soap or bar soap. We are so used to using soap that we rarely stop and wonder how this wonderful compound manages to help us clean ourselves day after day. Have you ever thought about what would happen if there were no soap? How else can we rid dirt off our bodies or our clothes?
Most of time, dirt comes in form of grease or oil which sticks itself onto surfaces and will not come off if only water is just used. This is because oil and grease are non-polar, which means that oil molecules are not charged and therefore are not attracted to polar substances such as water. Because of this, oil tends to stick with its own molecules or other non-polar substances.
On other hand, water is a polar substance which is made up of one positive and one negative charge, and therefore is a fragmented substance. With this, water dissolves salt easily because salt is made up of charged ions in which positive charge will be attracted to negative ions in water.
Due to fact of nature of oil and water, you will see that oil will not dissolve in water but remain clustered on surface. Also, oil and grease will stick onto plates and cutlery during cleaning, and no amount of water can completely remove it. That’s when soap comes in. All it takes is just one layer of soap with water and oil will be removed. How does this happen?
Well, soap is a unique substance of potassium fatty acid salts, produced through a chemical reaction called saponification. Its molecules are made up of a hydrocarbon chain, which is non-polar, as well as a carboxylate molecule which is polar. Therefore, non-polar part of soap – hydrocarbon chain, is not attracted to water but to oil (lipophilic). On other hand, carboxylate molecules which are negatively charged, are attracted to positively charged water molecules (hydrophilic).