What do you think it does to the surface tension?
why does adding soap to water reduce waters cohessiveness?
To understand what adding soap does to the surface tension of water and why it reduces water's cohesiveness, let me explain the underlying concepts.
Surface tension is a property of liquids, including water, that arises due to the cohesive forces between its molecules. It is the force that acts at the surface of a liquid, causing it to behave as if it has a thin film or "skin." This is why water droplets can form a spherical shape.
Soap molecules consist of two parts: a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. When soap is added to water, the hydrophobic tails of the soap molecules tend to cluster together, while the hydrophilic heads point outward toward the water.
Soap molecules disrupt the cohesive forces between water molecules. They effectively break the intermolecular hydrogen bonds that hold water molecules together, reducing the surface tension of water. This is because the soap molecules compete with water molecules to form weak bonds with each other, instead of forming stronger hydrogen bonds within the water network.
As a result, the cohesive forces within the water are weakened, making the water less "clingy" and more able to spread out. This is why adding soap to water reduces water's cohesiveness. The reduced surface tension also allows soap to penetrate more easily into tight spaces, making it effective at cleaning.
In summary, adding soap to water reduces water's surface tension and cohesiveness by disrupting the intermolecular forces between water molecules, allowing the soap molecules to interact more easily with both water and other substances.