How Soap Affects Floating Paperclip

What happens when soap is added to water with a floating paperclip?

A student places a small amount of water in a glass dish and then carefully places a small paperclip on the surface of the water. The paperclip floats. What happens if the student adds a drop or two of dish soap to the water? Check all that apply:

• The paperclip falls through the water to the bottom of the dish.
• The soap acts as a surfactant.
• The soap increases the surface tension of the water.
• The soap decreases the surface tension of the water.

Answer:

1. The paperclip falls through the water to the bottom of the dish.
2. The soap acts as a surfactant.
4. The soap decreases the surface tension of the water.

Explanation:

When soap is added to water with a floating paperclip, the soap acts as a surfactant. This causes the surface tension of the water to decrease, leading to the paperclip falling through the water to the bottom of the dish. The addition of soap disrupts the equilibrium that kept the paperclip floating on the water's surface.

The mechanism of floatation involves the density and mass of the object in relation to the water. The paper clip is lighter in weight compared to water, allowing it to float. However, any disruption to the surface tension, such as adding soap, can cause the paperclip to sink.

In summary, the addition of soap decreases the surface tension of the water, affecting the paperclip's ability to float. Understanding how different substances interact with water can help explain the behavior of objects on its surface.