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Cleansing Agents – Definition, Types, Properties, Uses

  • Last Updated : 19 Jan, 2022

In everyday life, chemistry plays a significant role. The most basic needs – shelter, food, clothing, and medicines – are all chemical substances. Organic, analytical, physical, inorganic, and biological aspects are all important in pharmaceutical chemistry. 

Chemistry has an impact on every part of the lives, both directly and indirectly. From the air we breathe to the food eaten, the housing people live in, and the emotions everyone experience, chemistry plays a critical role in daily lives. Pharmacists make the medicines taken by people while they are sick. Natural phenomena like digestion, leaf browning, and ice floating on water are all founded on chemical principles.

Cleansing Agents

Cleaning agents include soap and detergents. Detergents and soaps are frequently used to clean the dirt off the garments in daily lives. Soap and detergents are made up of chemicals. Let’s study Cleansing agents in some detail in this article. The word ‘detergent’ comes from the Latin word ‘detergere’ which means to scrub or clean. However, synthetic detergent is now referred to as detergent.

Soaps

Soap is made when sodium hydroxide or potassium hydroxide reacts with vegetable or animal fats in a saponification reaction. Soaps are salts comprising a lengthy chain of fatty acids that are potassium or sodium based. Soaps, by their very nature, are water soluble.

The saponification reaction occurs when an ester reacts with a base, resulting in the formation of alcohol and soap. Below is a reaction of the general saponification.

Ester + Base  → Alcohol + Soap

Soaps come in a variety of shapes, colors, and scents, including cakes, shampoo, and cream. Soaps are sodium or potassium salts of higher fatty acids (those with more than 12 carbon atoms) that have more than 12 carbon atoms. Soaps made of potassium are softer than those made of sodium. Shampoo, shaving cream, and bathing soaps all have potassium soaps in them. Sodium Soap is a type of toilet soap that is used for washing purposes. Soaps are prepared in two different ways,

  • Fat is hydrolyzed using a sodium or potassium hydroxide solution.

Adding salt separates the soap from the glycerol. Due to the common ion effect, soap precipitates out of the salt solution, leaving glycerol in the solution, which is soluble in salt.

  • Using NaOH or Na2CO3 to directly neutralize fatty acids.

Soaps react with these ions to produce calcium and magnesium salts, which are water-insoluble.

Higher fatty acid salts, such as calcium and magnesium, are insoluble in water and produce a sticky grey scum. As a result, soap is wasted,

the fabrics of clothing are destroyed.

Types of Soap

  1. Floating Soaps: Floating soaps are created by pounding tiny air bubbles before they harden.
  2. Toilet Soaps: They’re made with higher-quality fats and oils, and extra alkali is avoided. To make them more appealing, color and fragrances are added.
  3. Medicated Soaps: Antiseptics are used as an ingredient in various sorts of soaps. The antiseptic will aid in the killing of bacteria as well as dirt and dust on the surface.
  4. Soap powders and scouring: Soaps comprise soap, an abrasive (powdered pumice or finely divided sand), and builders such as sodium carbonate and trisodium phosphate.
  5. Soap Chips: Soap chips are formed by scraping little broken fragments of molten soap off of a cool cylinder.
  6. Soap Granules: They’re microscopic soap bubbles that have been dried.
  7. Shaving Soaps: To prevent quick-drying, shaving soaps contain glycerol. When they’re made, a gum called rosin is added. It produces sodium rozinate, a foaming agent.
  8. Transparent Soaps: They’re made by dissolving soap in ethanol and then evaporating the surplus.

Advantages of Soaps 

  1. Soap is less expensive and more widely available.
  2. With gentle water, it cleans garments well (Water that doesn’t contain Ca2+ or Mg2+).
  3. Soaps are completely biodegradable, meaning they break down in sewage microorganisms. As a result, there is no pollution of water.

Disadvantages of Soaps 

  1. Hard water with Ca2+ or Mg2+ does not work well with it.
  2. Soaps can’t be used in acidic solutions because the acids precipitate the insoluble free fatty acids, which stick to the clothes and impede the dyeing process.

Detergent 

A synthetic detergent is any synthetic chemical that is an excellent cleaning and can be used as a surface-active agent in both hard and soft water. It’s a non-soap cleanser that works by reducing the surface tension of an aqueous cleaning agent.

  • Synthetic detergents are yet another form of the cleaning agent. These are identical to soaps in that they possess all of the same qualities. They do not, however, contain any soap, and their chemical composition is very different than that of soaps.
  • These are suitable for usage in both soft and hard water because they produce foam in both. Calcium and magnesium salts, like their sodium salts, are detergents that are also water-soluble. Even in ice-cold water, some detergents produce foam.
  • Alkyl hydrogen sulfates of long-chain alcohols or alkyl benzene sulphonates are common names for synthetic detergents.
  • Soaps and synthetic detergents are both not completely biodegradable and pollute water.

Types of synthetic detergents 

  • Anionic detergents 

The soluble endpoints of the chains have anions. They are sulphonated long chains of hydrocarbons or alcohols with sodium salts. They’re made from long-chain hydrocarbons or alcohols that have been treated with strong sulphuric acid before being neutralized with NaOH.

Cleaning is aided by the anionic component of the detergent. They’re in toothpaste and cleaning products throughout the house.

  • Cationic detergents 

Quaternary ammonium compounds of amines with chlorides, acetates, or bromides make cationic detergents. At the soluble endpoints of the chain, they have cations. Cations are long-chain hydrocarbons with a positive charge on nitrogen atoms, while anions are chlorides, acetates, or bromides. They are costly and are employed as germicides.

Hair conditioners, for example, contain cetyltrimethylammonium chloride. As a result, al

mmonium salts are cationic detergents.

  • Non-ionic detergents 

They are devoid of any ions. When stearic acid and polyethylene glycol combine, a detergent is produced. Non-ionic detergents are liquid dishwashing detergents. This sort of detergent works in the same way as soaps in terms of cleaning activity. Micelle formation also helps to eliminate grease and oil. The main issue with detergent use is that bacteria cannot easily break down detergents with a highly branched hydrocarbon chain.

Where R is a chain of 11-17 carbon atoms and n = 8 to 12. They are mostly used for vessel cleaning. All of these detergents work in the same way as soaps in terms of how they work.

When stearic acid is combined with polyethylene glycol, a nonionic detergent is produced.

Advantages of detergent 

  1. Powdered detergents work well.
  2. These agents soften the water and increase the efficiency of the detergent powder.
  3. They also keep soap scum and insoluble salts off your clothing.
  4. These builders break up the oil and grease into small pieces on the surface of your garments.

Disadvantages of detergent 

  1. Detergents have the primary drawback of not being biodegradable.
  2. They pollute the soil and water.
  3. Some detergents contain too much alkali, which can cause fabric damage.
  4. When using a less expensive detergent, the color may fade.

Detergent Pollution 

Branched hydrocarbon chains in detergents pollute lakes, ponds, rivers, and other bodies of water. The presence of side chains, which prevent bacteria from attacking and breaking the chains, explains this. As a result, detergent molecules de

e slowly, accumulating on the surface.

Mechanism of Cleansing action of Soap 

A soap molecule is made up of two parts: a long hydrocarbon tail that is soluble in oil and another component that is soluble in water.

The hydrocarbon element of the soap dissolves in oil when it is introduced to an oily or greasy part of the cloth, keeping the head away from the oil. By rubbing large oil and soap molecules into little emulsified oil droplets in water, large molecules of oil and soap are broken up. A flow of water washes away the microscopic emulsified oil droplets. Emulsion anions resist each other, hence deposition does not occur. It’s an emulsion of oil and water. Soap and detergents both work in the same way when it comes to cleaning.

Sodium sulfate, inorganic phosphates, sodium perborate, foaming agents, and other additives make up the remaining 20% of active chemicals in commercial detergents. Phosphates from detergents aid the growth of algae and weeds in the water, depleting oxygen for sea animals. Therefore, synthetic detergents cause water pollution.

Difference Between Soaps and detergents 

SoapsDetergents
In hard water and saline water, they are ineffective.In hard water and saline water, they retain their effectiveness.
Biodegradable soaps are available.Non-biodegradable detergents have a branching hydrocarbon chain.
Natural sources, such as vegetable oils and animal fats, are used to make them.Synthetic derivatives are detergents.
In a hard water setting, they have a proclivity to produce scum.Scum does not form as a result of these chemicals.
Because soap is biodegradable, it is an environmentally friendly product.These substances can combine to generate a thick foam, which can kill aquatic life.

Example:

Sodium palmitate.

Example:

Deoxycholic acid.

Summary

Cleaning agents include soaps and detergents. Soaps are sodium or potassium salts of fatty acids with a greater fatty acid content. Sodium salts of alkyl hydrogen sulphates and sodium salts of long chain alkyl benzene sulphonic acids are used to make detergents. Soaps and detergents are made from emulsified oil droplets that are subsequently rinsed away by a stream of water.

Conceptual Questions 

Question 1: Soaps and detergents are basic, aren’t they?

Answer: 

Soaps are sodium or potassium-based fatty acid salts that dissolve in water. Soaps are created by chemically processing fats and oils, or their fatty acids, with a strong alkali. Salts are detergents and soaps. As a result, they have very basic features and can be classified as salts.

Question 2: Soap v/s detergent: what’s the difference?

Answer: 

Soaps are carboxylic acid salts with long chains of sodium. Detergents are sodium salts of benzene sulphonic acids with a lengthy chain. Some detergents cannot be biodegraded, although soaps can. Soaps have a modest cleaning activity compared to detergents, which have a strong cleaning action.

Question 3: Is the saponification procedure utilized on all soap?

Answer:

The saponification technique is used to make soap. The method and kind of soap, such as detergent, toilet soap, and detergent bar, are the only differences in the procedure. These soaps have distinct reactants, hence their products are different, but their derivatives, which are

al salts of fatty acids, are the same.

For Example: 

  1. Sodium salt of fatty acids is used as a detergent.
  2. Soap is a fatty acid potassium salt.

Question 4: Because soap contains a base, why do we apply it after cutting onions?

Answer:

Onions contain a sulphur – containing component that breaks down into sulphuric acid when hydrolyzed. As a result, when we wash our hands with soap, the sulphur impurity is neutralized and removed from our hands.

Question 5: How does use a detergent aid in the cleaning of filthy clothing?

Answer:

When soap is dissolved in water, the hydrophobic ends of the soap attach to dirt and lift it off the cloth. To begin, soap molecules create micelles, trapping dirt in the cluster’s center. Like particles in a colloidal solution, these micelles remain suspended in water.

Because of ion-ion repulsion, the different micelles present in water do not come together to create a precipitate. As a result, dust particles are caught in micelles (which stay suspended) and readily washed away with water.

As a result, soap micelles dissolve dirt in water and remove it.

Question 6: Explain the Advan

s and Disadvantages of Soaps?

Answer:

  • Advantages of Soaps
  1. Soap is less expensive and more widely available.
  2. With gentle water, it cleans garments well ( Water which doesn’t contain Ca2+ or Mg2+ ).
  3. Soaps are completely biodegradable, meaning they breakdown in sewage microorganisms. As a result, there is no pollution of water.
  • Disadvantages of Soaps
  1. Hard water with Ca2+ or Mg2+ does not work well with it.
  2. Soaps can’t be used in acidic solutions because the acids precipitate the insoluble free fatty acids, which stick to the clothes and impede the dyeing process.

Question 7: Explain the Disadvantages of Detergents?

Answer:

Disadvantages of Detergents

  1. Detergents have the primary drawback of not being biodegradable.
  2. They pollute the soil and water.
  3. Some detergents contain too much alkali, which can cause fabric damage.
  4. When using a less expensive detergent, the colour may fade.

Multiple Choice Questions 

Question 1: Formula of Soap?

  1. C17H35COONa
  2. C19H35COONa 
  3. C17H33COONa 
  4. C19H33COONa 

Answer:

  1. C17H35COONa

Question 2: Which solution is used to saponify fat or oil in the cold process?

  1. NaOH
  2. KOH
  3. HCl
  4. NaCl

Answer:

2. KOH 

A KOH solution is used to saponify a fat or oil in the cold process. A soft soap is created when potassium hydroxide (KOH) is utilized. It is not suitable for usage in harsh water.

Question 3: Which solution is used to saponify fat or oil in the hot process?

  1. NaOH
  2. KOH
  3. HCl
  4. NaCl

Answer:

  1. NaOH 

A heated method is used to saponify a fat or oil using NaOH solution. With NaOH in water, saponification of myristic acid to the sodium salt takes place. Hard soaps are created by using sodium hydroxide (NaOH).

Question 4: Soaps and synthetic detergents are both not completely biodegradable and pollute water.

  1. True
  2. False

Answer:

  1. True

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