Why Do Soap Bubbles Pop? | A2 ESL Science Reading Passage

Why can a bubble pop without anyone touching it? Read this short science passage, learn five useful words, and check your understanding with the questions below.

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Soap bubbles floating through the air. An explanatory illustration.

Reading Level

A2-B1

Word Count

190 words

Reading Passage

A soap bubble can float through the air, then suddenly disappear. It pops when the thin layer around it breaks. Even a bubble that nobody touches can pop.

The air inside is wrapped in a film of soapy water. This film has water between two layers of soap molecules. Molecules are tiny pieces of a substance, too small to see with your eyes.

Soap makes it easier for water to form a bubble. It reduces the pull at the water's surface. It also helps slow the loss of water from the film. However, soap cannot keep a bubble alive forever.

Some water can evaporate from the film into the air. As water leaves, the film becomes thinner. Eventually, a small part breaks, and the whole bubble opens up. The air escapes, and the bubble is gone.

Touch can break the film too. A dry finger can make a bubble pop, but a finger covered in soapy water may pass through it. The soap solution helps keep the film from breaking.

So a bubble does not need a sharp object to pop. Losing water or touching something dry can be enough.

The thin film, evaporation, and touch. An explanatory illustration.

Key Vocabulary

Word	Meaning
bubble	a pocket of air inside a thin liquid layer
film	a very thin layer
surface	the outside or top layer of something
evaporate	to change from liquid into gas
pop	to break open suddenly

Reading Questions

1. What is inside a soap bubble?
2. What lies between the two layers of soap molecules?
3. What happens to the film as water evaporates?
4. Why might a finger covered in soapy water pass through a bubble?
5. Does a bubble need a sharp object to pop? Give one reason from the passage.

Answers

1. Air is inside the bubble.
2. A thin layer of water lies between them.
3. The film becomes thinner and can break.
4. The soap solution helps keep the film from breaking.
5. No. It can pop when it loses water or touches something dry.

Short Summary

A soap bubble pops when its thin film breaks. Water loss and contact with dry objects can break the film.

More Easy Readings

• How Does Soap Clean? | A2 ESL Science Reading Passage

Science Sources

• Exploratorium: Soap and bubble films
• University of Illinois Extension: Science of Bubbles (PDF)