Washington Esthetician State Board Practice Exam

In what part of a surfactant molecule is the hydrophilic section found?

1. At the ends of the molecule

2. In the center of the molecule

3. Throughout the entire molecule

4. At the opposite end of the lipophilic section

The correct answer is: At the opposite end of the lipophilic section

The hydrophilic section of a surfactant molecule is found at the opposite end of the lipophilic section. Surfactants are composed of two distinct parts: a hydrophilic (water-attracting) head and a hydrophobic (water-repelling or oil-attracting) tail. This dual nature allows surfactants to interact with both water and oils, making them effective in a variety of applications, such as cleansing and emulsifying. By having the hydrophilic portion positioned opposite the lipophilic section, surfactants can effectively reduce surface tension at the interface between water and oil, allowing for better mixing and cleaning action. This characteristic is fundamental in the formulation of many personal care and beauty products, as it enables these substances to interact with and remove oils and dirt from the skin or hair. The other options do not accurately represent the structure of surfactants, as the hydrophilic and lipophilic parts are designed to function in opposition to each other to optimize their functionality.