Two types of detergents are used as cleansing agents. These are soaps and synthetic detergents. These improve cleansing properties of water. These help in removal of fats which bind other materials to the fabric or skin.

Soaps are the detergents used since long. Soaps used for cleaning purpose are sodium or potassium salts of long chain fatty acids, e.g., stearic, oleic and palmitic acids. Soaps containing sodium salts are formed by heating fat (i.e., glyceryl ester of fatty acid) with aqueous sodium hydroxide solution. This reaction is known as saponification.

Dishwashing liquids belongs to which category?

non-ionic detergents

The correct answer is option 4. non-ionic detergents.

Non-ionic detergents are a type of surfactant (surface-active agent) that do not contain any charged (ionic) entities in their molecular structure. Unlike anionic or cationic detergents, which have charged head groups, non-ionic detergents have a neutral overall charge.

Preparation of Dishwashing Liquids from Polyethylene Glycol and Stearic Acid:
One method of preparing dishwashing liquids involves the reaction of polyethylene glycol with stearic acid. Polyethylene glycol (PEG) is a water-soluble polymer with a hydrophilic nature, while stearic acid is a long-chain fatty acid with a hydrophobic nature.

When these two compounds react, they form a surfactant molecule known as a non-ionic detergent. In this molecule, the polyethylene glycol portion serves as the hydrophilic "head" group, while the stearic acid portion serves as the hydrophobic "tail" group. This arrangement allows the non-ionic detergent to interact with both water and oily substances, making it effective for cleaning purposes.

Properties and Applications:
Non-ionic detergents are widely used in dishwashing liquids and other cleaning products due to their versatility and mildness. Some key properties and applications of non-ionic detergents include:

1. Gentle on Surfaces: Non-ionic detergents are generally mild and gentle on surfaces, making them suitable for cleaning delicate items such as dishes, glassware, and utensils.

2. Versatile Cleaning: They have the ability to effectively remove grease, oils, and food residues from surfaces without relying on ionic interactions. This makes them versatile for use in various cleaning applications.

3. Low Foaming: Non-ionic detergents typically produce low levels of foam compared to anionic detergents, which can be advantageous in dishwashing liquids where excessive foaming may be undesirable.

4. Compatibility: They are compatible with hard water and are less prone to causing water hardness issues compared to anionic detergents.

Overall, non-ionic detergents, such as those prepared from polyethylene glycol and stearic acid, are effective and versatile surfactants commonly used in dishwashing liquids and other cleaning products for their ability to remove soils without relying on ionic interactions.