


Use a balloon filled with carbon dioxide to amplify sound waves

Suitable For

Grade 4



Time Required

 <12 Hours



What’s it about?

In a normal situation one will have difficulty hearing a watch tick more than half a metre away, because our ears are separated from the watch by air, which is not a very good conductor of sound. In this science experiment we will be looking which property of materials makes for better conduction of sound:

Topics covered

Sound conductor, Sonar, Density, Carbon dioxide

What will I need?


Procedure (Method)


How does it work?


Adding vinegar to the baking soda creates a chemical reaction. The baking soda is a base, while the vinegar is an acid; when the two combine they create carbon dioxide gas (CO2). When the balloon is filled with CO2, the molecules inside the balloon are compressed and closer to each other. Because the CO2 molecules inside the balloon are closer together or ‘denser’, they become a better conductor of sound waves than the ordinary air around you.

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