Soaps and detergents are commonly used cleaning agents that help in removing dirt, grease, and oil. They work by allowing oily substances to mix with water so that they can be washed away easily. Soaps are made from natural fats and oils, whereas detergents are synthetic cleaning agents. Both act as surfactants and help in effective cleaning.
Soaps
Soap is formed by the reaction of vegetable oils or animal fats with sodium hydroxide or potassium hydroxide, a process known as saponification. Chemically, soaps are the sodium or potassium salts of long-chain fatty acids that act as surfactants, reducing the surface tension of water to aid in cleaning. Although soluble in water, their effectiveness decreases in hard water.
A soap molecule has two distinct parts:
- Hydrophobic tail: This is the long nonpolar hydrocarbon chain that repels water and dissolves in oils and grease.
- Hydrophilic head: This is the ionic (polar) part that is attracted to water and helps the molecule stay dissolved in it.
Because of this dual nature, soap molecules can surround oily dirt and help remove it during washing.
Detergents
Detergents are synthetic cleaning agents made of long hydrocarbon chains with a functional group attached at one end. These functional groups are usually sulfate or sulfonate groups, which make detergents effective in cleaning.
Detergents are water-soluble and act as surfactants, meaning they reduce the surface tension of water and help remove dirt and grease. Unlike soaps, detergents work well in both soft and hard water and do not form scum.
A detergent molecule also has two parts:
- Hydrophobic tail: This is the long non-polar hydrocarbon chain that repels water and mixes with oil and grease.
- Hydrophilic head: This is the polar or ionic part that is attracted to water.
Because of this structure, detergents can easily remove oily dirt and keep it suspended in water, making them very effective cleaning agents.
Soap vs Detergent
Soaps | Detergents |
|---|---|
| Soaps are sodium or potassium salts of a long chain of carboxylic acids. | Detergents are ammonium or sulfonate salts of long chains of sulphates. |
| Soaps are mostly biodegradable. | Detergents are non-biodegradable. |
| Soaps do not clean well in hard, acidic, and saline water. | They are effective in hard, saline, and acidic water as well. |
| They form scum with hard water. | They form lather with hard water. |
| They are made from natural compounds such as fatty acids or vegetable or animal fats. | Detergents are synthetically derived from chemicals. |
| 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. |
Soaps are ionic in nature. | Detergents may be cationic, anionic, or non-ionic in nature. |
| They are not effective in hard water and saline water | They do not lose their effectiveness in hard water and saline water. |
| Examples: Sodium Stearate | Examples: Sodium lauryl sulphate |