What are Soaps and Detergents?

Cleansing agents are substances that remove dirt by removing fats (which are responsible for binding other substances to our skin or fabric.) These also play an important role in  enhancing the  cleansing properties of water. Chemical compounds used as cleaning agents, such as soaps and detergents, are made up of a variety of different components. Detergents remain unaffected by the hardness of the water and are therefore preferred over cleaning solutions. Soap has been around for more than 2,000 years.

Soaps

Soaps are the cleansers used  for a long time. Nowadays , there are a variety of soaps present in the market such as medicinal soap, toilet soap, laundry soap etc.The molecular structure of soaps is made up of long chains of molecules.

Preparation of Soaps

Glyceryl esters of fatty acid or fats are heated  with aqueous NaOH solution to make  soaps .This process is known as saponification.Glycerol formed is a by-product which is used in many cosmetics. Fractional distillation is used to recover the glycerol.

Equation of Soap Preparation:

Ester + Base → Alcohol + Soap

Preparation of detergents

Chemicals from petroleum, like Lauryl Alcohol are mixed with sulphuric acid (H2SO4) and turned into sodium salt to make synthetic detergents.Sodium lauryl sulphate is an example of detergent.

CH3(CH2)10CH2OH + H2SO4→ CH2(CH2)10CH2OSO3H + NaOH(aq) → CH3(CH2)10CH2OSO3Na

Lauryl Alcohol                           Lauryl hydrogen sulphate                      Sodium lauryl sulphate

Soaps and Detergents: Cleansing Action or Mode of Action

Structure

Most natural filth is oily, and oil does not dissolve in water. Soap molecules contain salts of long-chain carboxylic acids, such as sodium or potassium salts. Soap dissolves because the carbon chain disintegrates in oil and the ionic end disintegrates in water. As a result, the molecules of soap condense into micelle-like structures. One end of a micelle is oriented towards the oil droplet, while the other end, the ionic end, is directed away from the oil droplet. As a result, when it comes into touch with water, it forms an emulsion and aids in filth dissolving during the washing process.

Soaps and detergents are molecules in which the ends of the molecule differ in their properties.

• The hydrophilic end

• The hydrophobic end

The hydrophilic end dissolves and attracts water, whereas the hydrophobic end dissolves in hydrocarbons and repels water in nature. There is a chance that soap will be present on the water’s surface, causing the hydrophobic tail, which is insoluble in water, to align itself along the water’s surface. Various kinds of bathing soaps such as lux,dettol etc are used to remove dirt and oil from our skin. Detergents such as tide ,surf excel etc work well in hard water so they are used to remove dirt and oil from clothes .Detergents work in a similar way to create ionic micelles. This colloid of micelles remains suspended in water due to the repulsion between the identical negative charges in the micelles, which prevents them from coming together and precipitating out.Detergents are preferred over soaps as they get along well with hard water.

Properties of soaps and detergents

Properties of soaps

• Soaps are generally hard in nature. They are solid.

• Soaps are good at removing dirt and grime from various surfaces. In the cleaning process, soaps have two parts: a hydrophobic tail and a hydrophilic head. Both parts are equally vital.

• Soaps lather up when they come in contact with soft water.

• Emollients, found in many soaps, are responsible for moisturising our skin after we wash our hands with soap.

• Soaps are usually scented with a distinct smell that is added to them. These smells help us relax, quiet our minds, and eliminate the odours from our bodies.

Properties of detergents

• Detergents clean well even with hard water.

• They tend to soften water.

• Laundry detergents generate micelles that include an organic chain of lipids and oils, and an ionic section that contains dirt and dust.

Differences between soaps and detergents

Conclusion

Soaps and detergents are chemical compounds or mixtures of chemicals used as cleaning agents. Soap is a sodium or potassium salt of several combinations of fatty acids that have a cleansing activity in the water. However, detergent surfactants are far superior to cleaning solutions since they are unaffected by water hardness.