Soap makes bubbles because of its surface-active properties. Surface-active agents, also known as surfactants, have two parts: a hydrophilic (water-loving) head and a hydrophobic (water-hating) tail. When soap molecules are added to water, the hydrophilic heads attach to the water molecules and the hydrophobic tails point away from the water. This creates a thin film of soap molecules on the surface of the water.

If you blow into this film of soap molecules, it will form a bubble. The air trapped inside the bubble is surrounded by the soap film, which prevents the air from escaping. The soap film is strong enough to hold the air inside the bubble, even though the pressure inside the bubble is lower than the pressure outside the bubble.

The shape of a soap bubble is determined by the surface tension of the soap film. Surface tension is the force that acts on the surface of a liquid, causing it to behave like a stretched membrane. The surface tension of a soap film is lower than the surface tension of water, which is why soap bubbles can be so large.

The size of a soap bubble is also determined by the amount of soap in the solution. The more soap in the solution, the stronger the soap film and the larger the bubble can be.

Soap bubbles are a fun and fascinating phenomenon. They are made possible by the surface-active properties of soap molecules. The next time you see a soap bubble, take a moment to appreciate the science behind it.