Behind each bubble is a delicate balance of chemistry and physics that keeps it floating. That is until something breaks that balance.
Let’s break down the science of bubbles, and why they don’t last forever.
What exactly is a bubble?
A bubble is more than just trapped air. It’s made of a thin film of soapy water that surrounds a pocket of gas (usually air). This film is actually three layers:
One layer of soap,
one layer of water in the middle,
another layer of soap.
This structure helps the bubble stretch, bend, and float through the air while holding its shape.
Surface tension: The force holding it all together
Water molecules are strongly attracted to one another. This creates surface tension, a force that acts like an invisible elastic skin across the surface of water.
However, pure water has too much surface tension to form stable bubbles. It would snap back and collapse instantly. When you add soap, it weakens the surface tension just enough to allow the water molecules to stretch into thin films, without immediately breaking.
Soap molecules also stabilize the film by arranging themselves with their hydrophilic (water-loving) heads in the water and their hydrophobic (water-repelling) tails pointing outward. This reduces evaporation and helps the bubble resist popping, for a little while.
Why do bubbles pop?
Bubbles pop when anything disturbs the delicate balance of forces. Here are the main reasons:
Evaporation
Water in the film evaporates into the air. As the film dries out, it gets thinner and weaker—until it bursts.
Touching dry or rough surfaces
Dry surfaces, dust, grass, or even a sharp breeze can disrupt the surface tension and cause the film to collapse.
Gravity
Water inside the bubble slowly drains toward the bottom, making the top thinner over time. Eventually, the top gets so thin that it can no longer hold together.
Air pressure changes
Wind, motion, or other air currents can increase the pressure around or inside the bubble, causing it to pop.
How to make bubbles last longer
Humid air slows down evaporation.
Wet surfaces are less likely to pop the bubble.
Adding glycerin or corn syrup to your bubble mix thickens the film and helps it last longer.
Bubbles are a beautiful example of how science is at work in even the simplest things. A perfect balance of surface tension, air pressure, and moisture holds them together, but only for a moment.
