Chapter 15, Problem 98A

Interpretation Introduction

Interpretation: To give the reason for how water molecules interact with detergent molecules.

Concept Introduction: Detergent consists of two parts that are head and tail parts. When detergent molecules aggregate in water, they form organized structures which are known as a micelle.

Answer to Problem 98A

When detergent molecules aggregate in water, they form organized structures which are known as a micelle. The micelle is formed when detergent is added to water. The two parts of the detergent molecule dissolve in two different mediums. The head part of a micelle is polar in nature while the tail part is non-polar in nature.

Explanation of Solution

When detergent molecules aggregate in water, they form organized structures which are known as a micelle. The micelle is formed when detergent is added to water. The two parts of the detergent molecule dissolve in different mediums. The head part of a micelle is polar in nature while the tail part is non-polar in nature. The head group in a micelle is hydrophilic (the polar part of a molecule that is water-loving) the tail in a micelle is hydrophobic (the nonpolar part of a molecule that is not water-loving).

The particles of dirt and grease cannot be removed by water due to the surface tension of water. Therefore, detergents are added to it that contain surfactants which are useful in reducing the surface tension and also can work effectively. These surfactants act as emulsifiers and help in removing the dirt from the fibers.

Conclusion

Thus, the two parts of the detergent are a head and a tail part that are polar and non-polar in nature respectively that interacts with water molecules.