Courses for Kids
Free study material
Offline Centres

Difference between Soap and Detergent

Last updated date: 30th Nov 2023
Total views: 21.3k
Views today: 0.21k
hightlight icon
highlight icon
highlight icon
share icon
copy icon

What are Soap and Detergent: Introduction

To explain soap and detergent: In the field of chemistry, Soap and detergent are widely used cleaning agents that help in the removal of dirt, oil, and grease from various surfaces. While they serve a similar purpose, there are significant differences between soap and detergent in terms of composition, properties, and applications.


JEE Main Difference Between


Text, Images, Videos and PDF


JEE Main

Topic Name:

Difference between Soap and Detergent

Academic Session:



English Medium



Available Material:

Chapter-wise Difference Between Topics

Understanding characteristics of soap and detergent is a big part of chemistry, and it's especially important for students studying for tests like NEET and JEE. In this article, we'll look at some of the most important ways in which the characteristics of soap and detergent are the same and different.

Defining Soap:

Soap is produced through a chemical process called saponification, wherein a fat or oil is heated with an aqueous solution of sodium hydroxide (NaOH). The saponification reaction leads to the formation of soap, which is the potassium or sodium salt of higher fatty acids, such as lauric acid (C₁₁H₂₃COOH), palmitic acid (C₁₅H₃₁COOH), stearic acid (C₁₇H₃₅COOH), or linoleic acid (C₁₇H₃₁COOH).

 Composition and Production:

  • Soap Composition: Soap is a cleaning agent made from the reaction between a fat or oil and an alkali, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH). This chemical reaction, known as saponification, produces soap molecules consisting of a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail.

  • Soap Production: The traditional method of soap production involves a process called cold process or hot process, which requires the use of lye (sodium hydroxide or potassium hydroxide) and fats or oils. The fats or oils are heated, mixed with the alkali, and then allowed to cure. This process yields solid soap bars.

Defining Detergent:

Detergents are described as salts of long chain hydrocarbons with 12-18 carbon atoms, typically in the form of ammonium, sulphonate, or sulphate compounds. In particular, detergents commonly refer to the sodium salts of long chain sulphonic acids. Unlike soaps, detergents have the advantage of being effective in hard water environments as well. This is because the calcium or magnesium salts of detergents, similar to their sodium salts, are soluble in water.

Therefore, detergents do not precipitate as curdy white solids when exposed to hard water. Additionally, detergents can be utilized in acidic solutions since fatty acids and sulphonic acids have solubility in water.

Composition and Production:

  • Detergent Composition: Unlike soap, detergents are synthetically produced cleaning agents that contain surfactants derived from petroleum products. Detergents can be classified into two types: anionic and cationic. Anionic detergents have a negatively charged hydrophilic head, while cationic detergents have a positively charged hydrophilic head.

  • Detergent Production: Detergents are manufactured using chemical processes that involve the reaction of various petrochemical compounds. The raw materials undergo several steps, including sulfonation, neutralization, and drying. The resulting product is a powdered or liquid detergent.

Soap and Detergent Difference







Derived from the reaction of fat/oil and alkali

Synthetic compounds derived from petroleum products


Chemical Structure

Salt of a fatty acid

Surfactants with anionic or cationic properties


Hydrophilic Head

Polar, hydrophilic head (COONa or COOK)

Negatively or positively charged hydrophilic head


Hydrophobic Tail

Nonpolar, hydrophobic tail (hydrocarbon chain)

Nonpolar hydrophobic tail (hydrocarbon chain)




Some detergents are non-biodegradable


Reaction with Hard Water

Forms insoluble scum due to calcium/magnesium ions

Not affected by hard water


Cleaning Efficiency

Effective in removing dirt, oil, and grease stains

More effective in removing oil and grease stains


Environmental Impact

Environmentally friendly (biodegradable)

Varies; some detergents may be harmful to the environment



Personal hygiene, household cleaning, industrial uses

Laundry, dishwashing, household cleaning, industrial uses

So from the above definition and table, we understand what is soap and detergent , soap and detergent difference and different characteristics of soap and detergent.


Soap and detergent differ significantly in their chemistry and properties. Soap is derived from the saponification of fats or oils with an alkali and consists of carboxylate salts with a polar hydrophilic head and a nonpolar hydrophobic tail. It is biodegradable but reacts with hard water, forming scum. 

Detergents, on the other hand, are synthetic compounds made from petroleum sources and contain various functional groups, such as ammonium, sulphonate, or sulphate salts. They have anionic, cationic, or nonionic hydrophilic heads and a nonpolar hydrophobic tail. Detergents are effective in hard water and have superior cleaning efficiency for oil and grease stains. They find wide applications in laundry, dishwashing, household cleaning, and industrial processes.

FAQs on Difference between Soap and Detergent

1. What are different types of soap?

All soaps are produced through the process of saponification, which involves boiling fats and oils with a soluble hydroxide. However, the choice of raw materials used in soap production can vary, leading to different types of soaps. 

  • Toilet Soaps: Prepared using higher quality fats and oils, with added colors and fragrances for attractiveness.

  • Floating Soaps: Air bubbles are beaten into the soap mixture before it solidifies.

  • Medicated Soaps: Include antiseptics like Savlon or Dettol, and sometimes deodorants for pleasant scent.

  • Shaving Soaps: Contain glycerol to prevent drying and often include rosin for improved lathering.

  • Laundry Soaps: Contain fillers such as sodium silicate, borax, and sodium carbonate.

  • Soap Chips: Produced by pouring molten soap onto a cool cylinder and scraping off small, broken pieces.

2. What are different types of detergent?

Detergents can be categorised into three types based on their chemical properties. They are anionic, cationic, and non-ionic detergents.

  • Anionic detergents are named so because a significant portion of their molecules consists of anions, which play a role in their cleansing action.

  • Cationic detergents are named as such because the major part of their molecule is composed of cations, which are responsible for their cleansing action.They are quaternary ammonium salts containing long alkyl chains and are commonly used as germicides

  • Non-ionic detergents do not contain any ions in their structure.They are typically esters of high molecular mass alcohols, obtained through the reaction between polyethylene glycol and stearic acid.

3. Explain the difference between soap and detergent in chemical structure?

Soap molecules consist of a long hydrocarbon chain attached to a polar carboxylate group. This structure gives soap its amphiphilic nature, with the hydrophobic tail repelling water and attracting oil, while the hydrophilic head interacts with water. Detergent molecules also have a hydrophobic tail and a hydrophilic head, but their chemical structure can vary. Anionic detergents have a negatively charged head, cationic detergents have a positively charged head, and non-ionic detergents have an uncharged polar head. These variations in the chemical structure of soap and detergent enable them to solubilize and remove dirt, oil, and grease effectively in different cleaning applications.

4. Explain soap and detergent reaction with hard water.

To explain Soap and detergent reaction with hard water, First we have to know what is Soap and detergent. Soap and detergent are cleaning agents used to remove dirt, oils, and stains from surfaces. Soap is made from natural fats or oils, while detergents are synthetic compounds designed for specific cleaning purposes. Soap reacts with hard water by forming insoluble precipitates called soap scum, due to the reaction between the soap molecules and the calcium and magnesium ions present in hard water. This soap scum can cause residue and reduce the cleaning effectiveness of soap. On the other hand, detergents are specifically formulated to work effectively in hard water. They contain synthetic surfactants that do not form precipitates with the calcium and magnesium ions. Detergents can effectively clean in hard water by emulsifying dirt and oils without leaving behind soap scum, making them a preferred choice for cleaning in areas with hard water.

5. Concisely describe the soap and detergent difference with an example of biodegradability.

Soap and detergent differ in terms of biodegradability. Soap is biodegradable as it is derived from natural fats or oils and can be broken down by microorganisms into simpler, non-toxic substances. An example of a biodegradable soap is castile soap, which is made from vegetable oils. On the other hand, many conventional detergents are less biodegradable due to their synthetic nature and complex chemical compositions. For example, some laundry detergents contain surfactants like linear alkylbenzene sulfonates (LAS) which are slower to degrade in the environment. However, there are also biodegradable detergents available in the market that are formulated using environmentally friendly surfactants, making them a more sustainable alternative.