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Difference Between Soap and Detergent

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Soaps and Detergents are cleaning agents that are used to remove dirt and other undesirable particles from the human body, its clothes, and other surfaces. Both soap and detergents are used for cleaning action but there are quite differences between them, and the differences between them if discussed in the article. In general, soap is the sodium or potassium salt of fatty acids while detergents are long-chain carboxylic acid quaternary ammonium or sulfonate salts. 

In this article, we will learn about Soap, Detergents and their properties, their differences, and others in detail.

What are Soaps and Detergents?

Soaps and detergents are the basic cleaning product that are used for cleaning various objects, soaps are generally used to clean soft and delicate objects such as human skin and others, whereas detergents are used to clean rough objects and they have a rough action on the human skin. Soap and Detergents are called Surfactants as they reduce the surface tension of water.

Now let’s learn about soap and others in detail in this article.

Soaps Definition

Soap is a compound made by combining Sodium Hydroxide or Potassium Hydroxide with vegetable oil or animal fats in a saponification reaction. Soaps are potassium or sodium salts of fatty acids with a long carbon chain. Soaps are naturally water-soluble.

A soap molecule is made up of two components. These two components are referred to as:

  • Hydrophobic tail: This part of the soap is water-repellent in nature and dissolves in oils. It is ionic in nature.
  • Hydrophilic head: This part of the soap molecule is water attractive or water-loving and dissolves in water. It is made up of a long chain of hydrocarbons.

Properties of Soap

Soap of have various properties that differentiate them from detergents. Some of the properties of the soap are,

  • Soaps are large chain aliphatic compounds. They are formed by reacting Potassium or Sodium salts with fatty acids
  • Soaps are prepared using a reaction called saponification.
  • Soaps are the substances that reduces the surface tension of the liquid in which they are dissolved.
  • A soap molecule has two parts a Hydrophobic tail and a Hydrophilic head.

Manufacturing of Soap

A soap consists of long-chain fatty acids with a metal ion head. Soaps are sodium or potassium salt of long-chain fatty acid. The process of making soap is called saponification. In Saponification, oil and fat are heated and then reacted with alkali which results in the formation of soap, water, and glycerine. The other process of making soap is Neutralization. In the Neutralization method, oil and fats are hydrolyzed with the help of high-pressure steam which results in the formation of Glycerine and crude fatty acid. The so-formed fatty acid then undergoes distillation and is then neutralized by alkali to produce soap and water.

Detergents Definition

Detergents are compounds that have ionic groups connected to the end of a lengthy hydrocarbon chain. Detergents are long-chain carboxylic acid quaternary ammonium or sulfonate salts. 

Detergents, often known as surfactants, are substances that lower water’s surface tension. Detergents were developed during World War 2 due to the lack of vegetable oils to make soaps. Detergents also contain two parts. 

These are:

  • Hydrophobic Tail: This part of the detergent is water-repellent similar to the soaps. It is the ionic or polar or charged group that is present at the end of the hydrocarbon chain.
  • Hydrophilic Head: This part is water attractive or water-loving. It is made up of a long alkyl hydrocarbon chain.
Hydrophobic Tail and Hydrophilic Head of a Soap


Types of Detergents

Detergents are further classified into 3 types depending on the polarity of the polar group or hydrocarbon chain. These are:

  • Cationic Detergents
  • Anionic Detergents
  • Non-ionic detergents

Properties of Detergents

Various properties of the detergents are,

  • Detergents are Potassium or Sodium salts of a long alkyl chain that contains a sulfonate group at the end of it.
  • Detergents are water-soluble compounds.
  • Detergents reduce the surface tension of water and are called surfactants.
  • Detergents are soluble in water like soaps. Detergents are even soluble in hard water and do not form scum so they overcome the major limitation of soap.
  • This is because the ionic group present in detergents does not interact with the Mg or Ca ions present in hard water.

Manufacturing of Detergent

Detergents are manufactured by two methods, anionic surfactant, and non-ionic surfactant method. In Anionic Surfactant Method, hydrocarbons that are derived from petrochemicals react chemically to produce acids that resemble fatty acids. These newly produced acids are reacted with alkali to give an anionic surfactant. In the Non-Ionic surfactant method, hydrocarbons are first converted to alcohol which then is reacted with ethylene oxide. After the reaction with ethylene oxide, it is then reacted with acid-containing atoms of sulfur to give another anionic surfactant.

Difference between Soap and Detergent

The difference between soap and detergent is that soap is a fatty acid and detergent is a combination of surfactants. We use them to clean the house. To distinguish between soap and detergent, we must analyze their characteristics:




1. Soaps are sodium or potassium salts of a long chain of carboxylic acids. Detergents are ammonium or sulfonate salts of long chains of carboxylic acids.
2. Soaps are mostly biodegradable. Detergents are non-biodegradable.
3. Soaps do not clean well in hard, acidic, and saline water. They are effective in hard, saline, and acidic water as well.
4. They form scum with hard water. They form lather with hard water.
5. They are made from natural compounds such as fatty acids or vegetable or animal fats. Detergents are synthetically derived from chemicals.
6. Soap is generally prepared from plant and animal fats through saponification.  Petroleum (Petrochemicals) was found to be a plentiful source for the manufacture of detergent.
7. Soaps are not ionic in nature. Detergents may be cationic, anionic, or non-ionic in nature.
8. They are not effective in hard water and saline water They do not lose their effectiveness in hard water and saline water.
9. Examples: Sodium Stearate Examples: Sodium lauryl sulfate

Cleansing Action of Soap and Detergent

The Cleansing Action of the Soap and Detergent is discussed below,

Step 1: Make the surface wet using water which is to be cleaned.

Step 2: Apply soap and detergent to the surface which is to be cleaned. The solution of soap and water gets absorbed by the surface and they are called surfactants.

Step 3: Miscelle is formed which consists of a hydrophobic tail and hydrophilic head. The hydrophobic head is a long-chain fatty acid hence it gets attached to dirt and oil while the hydrophilic head which is a metal ion attaches to the water molecule because of its polar nature.

Step 3: The clothes are rubbed together by hand or in a washing machine the dust particle breaks down and the hydrophobic part of the soap absorbs the dust particle which in term removes the dirt from the surface. Now the running water is used to remove the dust particle and the surface is cleaned in such a way.

Now the wet clothes or object is allowed to dry and the clean surface clothes are used again.

Read More on Cleansing Action of Soaps and Detergents

FAQs on Soaps and Detergent

Q1: What are Detergents?


Detergents are ammonium or sulfonate salts of long chains of carboxylic acids. Detergents are also known as surfactants as they reduce the surface tension of water. 

Q2: What are Soaps?


Soaps are cleaning agents made from the combination of animal fats or vegetable oils with Potassium or Sodium salts by the saponification reaction.

Q3: What are types of Detergents?


The different types of detergents are:

  • Cationic Detergents Example, Cetyltrimethylammonium Bromide
  • Anionic Detergents Example, Sodium Lauryl Sulphate
  • Non-Ionic Detergents Example, Pentaerythrityl Stearate

Q4: What is Difference between Soap and Detergent?


Soap and detergent are commonly used cleaning agents, they both are used for cleaning purposes yet the basic difference between them is, Soaps are derived from animal fats and vegetable oils and are primarily utilized for cleansing purposes. On the other hand, Detergents are cleaning agents made from synthetic surfactants and are specifically designed to eliminate dirt and stains from various surfaces, fabrics, and materials.

Q5: Which is Better in Cleaning Soap or Detergent?


Detergents are more powerful cleaning agents than soaps as they work effectively in both soft and hard water. It is important to note that detergents are rougher and harsher compared to soaps.

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Last Updated : 05 Jun, 2023
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