How does the addition of soap to water affect its surface tension?

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Question: How does the addition of soap to water affect its surface tension?

Options:

Correct Answer: Decreases surface tension

Solution:

The addition of soap decreases the surface tension of water by disrupting the cohesive forces between water molecules.

How does the addition of soap to water affect its surface tension?

How does the addition of soap to water affect its surface tension?

Step 1: Understand what surface tension is. Surface tension is the force that makes the surface of water behave like a stretched elastic sheet.
Step 2: Know that water molecules are attracted to each other. This attraction creates strong cohesive forces that keep the water molecules together.
Step 3: Learn that when soap is added to water, it mixes with the water molecules.
Step 4: Realize that soap molecules have a special structure. One part of the soap molecule likes water (hydrophilic) and the other part does not (hydrophobic).
Step 5: Understand that the soap molecules disrupt the cohesive forces between the water molecules. This means the water molecules are not as strongly attracted to each other anymore.
Step 6: Conclude that because the cohesive forces are weakened, the surface tension of the water decreases when soap is added.

Surface Tension – Surface tension is the elastic tendency of a fluid surface that makes it acquire the least surface area possible, primarily due to cohesive forces between liquid molecules.
Effect of Surfactants – Surfactants, like soap, reduce surface tension by interfering with the cohesive forces between water molecules, allowing for easier spreading and mixing.