Difference Between Soap and Detergent

Introduction

Before the 18th century, soaps were not developed. Around 1790 the soaps are manufactured from sodium chloride i.e. common salt in the form of caustic soda (Sodium Hydroxide). Then around 1823 to 1889 chemist Michel Eugene discovered the manufacturing of soap from natural oils and fats. Detergents were manufactured in around 19’s as synthetic cleaners. Detergents are manufactured in America for cleaning and dishwashing purposes. People get confused about soap and detergents but they are two separate reagents. Soaps are manufactured from natural ingredients whereas detergents are synthetic material sulfonates of alkyl benzene ($\mathrm{RSO_{4}}$).

What are Soaps?

Soaps are salts of sodium or potassium, some natural fatty acids. Soaps are manufactured by the saponification of these fatty acids. Some commonly found soaps are sodium oleate, sodium stearate, etc. these are produced from the saponification of palmitic acid, oleic acid, and stearic acids. Soaps are used to remove oil and dirt and for cleaning purposes.

Earlier the manufacturer used ashes of wood or plants, and animal fats for soap making. The potassium carbonate present in the plant ashes is boiled and animal fats are added to them. The fats present in the mixture react with potassium carbonates to form soap. This process is called saponification. The process is then improved after the production of caustic soda from brine. Michel Eugene has done saponification in a chemical laboratory by splitting the fats into alkali of fatty acids.

Characteristics of Soaps

The soaps are salts of sodium and potassium with fatty acids and are produced by the saponification process. Soaps have the following characteristics.

• In the Saponification process triglycerides and carboxylic acids reacts with base sodium or potassium hydroxides to form soaps. The triglycerides broke into fatty acids and are neutralized by the base, and glycerol is left as a side product.

$$\mathrm{HCOOR_{1}\:+\:XOH\:\rightleftarrows\:XCOOR_{1}\:+\:H_{2}O}$$

• The general formula of soaps is $\mathrm{RCOOX}$ , in which 𝑅 is a long chain of hydrocarbons and 𝑋 is an alkali metal.

• Examples of soap are Sodium stearate, Sodium Oleate, and Sodium Palmitate has a long chain of 16- carbon atoms.

• The soaps have two components; a hydrophilic head and a hydrophobic tail.

• reduce the surface tension between water and dirt or oil. This helps remove the dirt from clothes.

• The hydrophobic end sticks to the oily side and the hydrophilic side is towards the water, they form a micelle around the dirt and remove the dirt from the clothes.

• Soaps are hard and last long.

• Soaps are cleansers made from natural fatty acids.

• Soaps form lather with water.

• Soaps have fragrance.

What are Detergents?

Detergents are surfactants that reduce the surface tension of water. They are sulfonates of alkly benzene chain. They are represented by a common formula i.e. $\mathrm{RSO^{-}}$, $\mathrm{Na^{+}}$, in which 𝑅 is a long chain of alkyl groups. Alkyl groups are nothing but a long chain of hydrocarbons.

Earlier, Detergents are manufactured from the sulfates of castor oil used in the leather industry. These are assumed as the first synthetic detergents. During world war when the availability of natural fats reduced chemist’s manufactured synthetic detergents from short-chain of alkyl naphthalene-sulfonates by reacting with propyl or butyl alcohols and sulfonation. Detergents are of three types −

• Cationic Detergents − In these detergents, the end group is a cation or positively charged ion. They are ammonium salts of Bromides, chlorides, or acetates. The cation group present in the detergents helps in the cleansing property of detergents. They are quite expensive and have antibacterial properties. These are majorly used in conditioners.

Example − Cetyltrimethylammonium bromide.

• Anionic Detergents − Anionic detergents have an anion or negatively charged ion at the end of the hydrocarbon chain of detergent. The negatively charged ion in the detergent helps in the cleaning of dirt. These are sodium salts of long-chain hydrocarbons. They are used in shampoos, toothpaste, etc

Example − Sodium Lauryl Sulfate.

• Non-Ionic Detergents − In this type of detergent there is no ionic group. They are mainly used in liquid dishwasher. The cleansing is done by micelle formation.

Example − Pentaerythrityl Stearate.

Characteristics of detergents

Detergents are a long chain of benzene sulfonates. They have the following characteristics.

• Detergents are also amphiphilic i.e. have a hydrophilic head and hydrophobic tail.

• The hydrophilic head is made up of a long alkyl hydrocarbon chain, and the hydrophobic tail is an ionic group.

• Detergents are soluble in hard and soft water both.

• They have a long chain of alkyl hydrocarbons with a sulfonate group at the end of the chain.

• They are manufactured synthetically.

• They are biodegradable.

• They are used for many household purposes like dishwashers, shampoos, conditions, toothpaste, and other commercial purposes like floor cleaning, laundry, etc.

Difference Between Soap And Detergents

The soap and detergents are quite different from each other. Let’s look at the main differences between soaps and detergents.

Soap	Detergents
They are long-chain hydrocarbons of potassium and sodium carboxylic acid.	They are a long-chain alkyl group of sulfonates.
They are written commonly as 𝑅 − 𝐶𝑂𝑂𝑁𝑎.	These are written as 𝑅 − 𝑆𝑂3𝑁𝑎.
They do not form lather in hard water.	They form lather with hard water.
They are formed from natural fatty acids like vegetable oil or animal fat.	They are manufactured synthetically and have a branched hydrocarbon chain.
The process of manufacturing soaps is known as saponification.	The detergents are manufactured by synthetic methods through various chemical reactions.
They are biodegradable.	They are non-biodegradable.
Example − Sodium Palmitate, Sodium Oleate, Sodium Stearate.	Example − Sodium Laural Sulfate, Pentaerythrityl Stearate, Cetyl trimethyl ammonium bromide, etc.

Conclusion

In this tutorial, we have discussed soaps and detergents. We get to know that soaps are long-chain potassium or sodium salts of carboxylic acids with a long chain of hydrocarbons. Detergents are long-chain salts of sodium with a long chain alkyl with a sulphate group. Soaps irritate the skin and form scum when used with hard water. Detergents do not form scum, they form lather when treated with hard water. Soaps are used for lubrication and cleaning purposes. Detergents are used in many household materials like shampoo, Toothpaste, conditioners, dishwashers, etc. Soaps are not classified further, but detergents are classified into three categories, cationic, anionic, and non-ionic detergents.

FAQs

1. What happens when Soaps are treated with Hard water?

Soaps when treated with hard water, they form white colour soap scum them. This happens due to the presence of magnesium and calcium ions in hard water.

2. Which is more reactive Soaps or Detergents?

Soaps are less reactive than detergents. Detergents are more reactive in hard water, saline, or acidic water than soaps as they do not form scum with these materials.

3. What are the cons of using detergents?

Detergents are manufactured with synthetic materials, and do not degrade easily that’s why they cause harm to our environment. They are more expensive than soaps.

4. What are the uses of anionic detergents?

Anionic detergents are negatively charged surfactants, they are used in handwashes, body washes, laundry detergents, kitchen cleaners, etc. They are negatively charged and help remove oils and grease. They can cause skin irritation.

5. How do commercial industries reduce the potency of anionic detergents?

The commercial industries blend anionic detergents with ionic detergents to balance the potency of detergents so that they do not harm the skin.