Detergents are sodium or potassium salts of long chains of sulphonic acid.

Explanation:
Detergents are cleaning agents that are used to remove dirt, grease, and stains from various surfaces. They are commonly used in household cleaning, laundry, and dishwashing products. Detergents can be classified into two types: soap-based detergents and synthetic detergents.

Synthetic detergents are the most commonly used type of detergents. They are made from petroleum-based raw materials and are generally more effective than soap-based detergents. Synthetic detergents are composed of different components, including surfactants, builders, and additives.

The main component of synthetic detergents is the surfactant. Surfactants are molecules that have both hydrophilic (water-loving) and hydrophobic (water-repelling) parts. This unique structure allows surfactants to interact with both water and oil, which makes them excellent cleaning agents.

The surfactants used in detergents are typically long-chain molecules. These long-chain molecules can be derived from different sources, such as aldehydes, ketones, carboxylic acids, or sulphonic acids. In the case of detergents, the surfactants are sodium or potassium salts of long chains of sulphonic acid.

Importance of sulphonic acid in detergents:
Sulphonic acid is a strong acid that is commonly used in the production of detergents. It has several properties that make it suitable for this purpose:

1. Water solubility: Sulphonic acid is highly soluble in water, which allows it to dissolve easily and mix uniformly with other detergent components. This ensures the detergent can be easily dispersed in water and effectively clean various surfaces.

2. Stability: Sulphonic acid is stable under a wide range of pH conditions. This means that the detergent can maintain its cleaning effectiveness even in acidic or alkaline solutions.

3. Foaming ability: Sulphonic acid has excellent foaming properties, which is important for the formation of lather during the washing process. The foam helps to lift off dirt and grease from surfaces and allows for better cleaning.

4. Cleaning power: Sulphonic acid has strong cleaning properties due to its ability to interact with both water and oil. The hydrophilic part of the molecule dissolves in water, while the hydrophobic part interacts with oil and grease, effectively removing them from surfaces.

In conclusion, detergents are sodium or potassium salts of long chains of sulphonic acid. Sulphonic acid is an important component of detergents due to its water solubility, stability, foaming ability, and cleaning power.