Content Writer-SME
Soaps are produced from natural ingredients like plant oils or acids derived from animal fat. Detergents are synthetic, man-made derivatives. They are not easily biodegradable. Detergents are favorable compared to soaps for washing clothes in hard water because they are the better cleansing agents.
The primary difference between soap and detergent arises on the basis of their constituent particles such as soap is a metal salt of fatty acid whereas detergent is a potassium or sodium salt of a long alkyl chain.
Read Also: Soaps and Detergents
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Key Terms: Soaps, Detergents, Potassium or Sodium Salts, Fatty Acids, Alkyl Benzene Sulfonates, Carboxylic Acid
Difference Between Soaps and Detergents
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Apart from their composition, the major differences between soap and detergent can also be underlined by their usage and effectiveness in cleaning dirt from clothes. Here are the key differences between Soaps and Detergents:
| Basis of Comparison | Soaps | Detergents |
|---|---|---|
| Definition | Soaps are ‘-COONa’ group attached to a fatty acid or a carboxylic acid that has a long alkyl chain. | Detergents are also cleansing agent have a ‘-SO3Na’ group attached to a long alkyl chain. |
| Nature | They are perfectly biodegradable. | Those detergents with a branched hydrocarbon chain are not biodegradable. |
| Extraction | They are extracted from natural sources like animal fats and vegetable oils. | They are extracted synthetically or are synthetic derivatives. |
| Impact on Environment | They are environment-friendly as they are biodegradable. | They can cause a thick foam which can be deadly to aquatic life. |
| Scum Formation | In an environment of hard water, soaps tend to form scum. | Detergents do not form scum. |
| Effectiveness | They do not become effective in hard water and saline water. | They are effective in both hard water and saline water. |
| Examples | Examples of soaps are sodium palmitate and sodium stearate. | Some detergents are deoxycholic acid and sodium lauryl sulfate. |
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Preparation of Soap
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Saponification of oils and fats is the most commonly used method in the preparation of soaps. Oils and fats, when heated and then reacted with an alkali, produce soap, water and glycerin. This is one of the most common methods of preparing soaps. Soaps can also be prepared by the neutralization of fatty acids with an alkali.
When oils and fats are hydrolyzed with a highly pressured steam, they produce glycerin and crude fatty acids. These fatty acids are then purified by the method of distillation and then neutralized with alkali to produce water and soap. Hard soaps are produced by alkali like sodium hydroxide while those soaps made of potassium are soft.
They are utilised in liquid hand wash soaps and shaving creams. Soaps contain both hydrophilic and hydrophobic ends. The carboxylate end of the soap molecule is hydrophilic while the other end with the hydrocarbon chain is hydrophobic. The hydrophobic end attracts grease and oil and repels water.
Check More Carbon and Compounds
How do Soaps and Detergents Help in Cleaning out Dirt?
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There are basically four steps involved in the cleaning of a dirty surface. Firstly, the surface is watered and made wet. Then, soap or detergent is applied to the dirty area in order to be absorbed. Soaps or detergents are also known as surfactants or surface-active agents. The molecules that are surface-active present in soaps and detergents dissolve in water.
- This solution then helps in removing the surface tension or the force that binds the molecules on a surface together.
- This facilitates the easy spreading of water on the surface and the surface gets soaked.
- Later, the surface, specifically, the clothes are rubbed together by hands or in the washing machine.
- At this stage, the surface-active molecules work to separate the dirt from the clothes and deposit them in water.
- This separated dirt is then prevented from being re-deposited on the clothes as the dirt particles are covered with soap and detergent molecules.
- This is washed away later until which they remain suspended in the water.
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Versatile Nature of CarbonThings to Remember
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- Soaps are the sodium salts of fatty acids or carboxylic acids with long chains.
- Detergents are the sodium salts of benzene sulphonic acids with long chains.
- Soaps are biodegradable while some detergents are non-biodegradable.
- Detergents have a stronger cleaning effect than soaps.
- Soaps and detergents are surfactants due to which they are used for cleaning dirt.
- Soaps are prepared from fats and oils or their fatty acids, neutralized with a heavy alkali.
- The chemical reaction that produces soap is called saponification.
Read Further: Important Notes on Carbon and its compounds
Sample Questions
Ques. What are the properties of soaps? (2 Marks)
Ans. They are soluble in water as they are fatty acid sodium salts. They are made from fats and oils or their fatty acids by neutralizing them with a heavy alkali.
Ques. What is the difference between a soap and a detergent? (3 Marks)
Ans. Soaps are the sodium or potassium salts of fatty acids or carboxylic acids with long chains. Detergents are the sodium or potassium salts of long-chain benzene sulphonic acids having long chains.
While all soaps are completely biodegradable, some detergents are not biodegradable or are non-biodegradable. Detergents are stronger when it comes to cleaning dirty surfaces or clothes. Detergents are synthetic products and are mostly made from petroleum while soaps are prepared from natural fats.
Ques. Describe saponification. (2 Marks)
Ans. Saponification is the chemical reaction that produces soap. Oils and fats are initially hydrolyzed in the presence of a high-pressure steam to produce glycerin and crude fatty acids. These fatty acids are neutralized with a heavy alkali to produce soap and water.
Ques. Are detergents better than soaps in cleaning dirty surfaces? (2 Marks)
Ans. Yes. Detergents are more effective on stains and for maintaining the colour of clothes. This is because of their ability to clean surfaces even in hard water. On the other hand, soaps are less effective in cleaning clothes but are kinder on the environment and skin.
Ques. Give examples for everyday detergents. (2 Marks)
Ans. Laundry and fabric softeners, all-purpose cleaners and mixtures intended for soaking, rinsing or bleaching are everyday detergents.
Ques. Give examples for soap compounds. (2 Marks)
Ans. Sodium stearate, sodium oleate and sodium palmitate are examples for soap compounds.
Ques. What are some of the detergent compounds? (2 Marks)
Ans. Deoxycholic acid and sodium lauryl sulphate are some of the detergent compounds commonly used.
Ques. Do detergents produce scum? (2 Marks)
Ans. No. Soaps produce scum when used with hard water. This is because of the presence of calcium and magnesium ions in hard water that reacts with soap to produce a white solid substance called scum.
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