The singing spoon dry ice experiment is a simple science project that illustrates the concepts of sublimation and Bernoulli’s principle. Touching a metal spoon to dry ice makes the spoon sing or scream. Here’s what you do and a look at how it works.
Singing Spoon Materials
Basically, all you need is dry ice and a spoon. If you have metal tongs for handling the dry ice, those work too.
- Dry ice (solid carbon dioxide)
- Metal spoon or tongs
- Cup of hot water (optional).
Make the Spoon Sing
Press the spoon against a piece of dry ice. The spoon vibrates against the dry ice, producing a sound describing as singing, screaming, or shrieking. Warming the spoon by dipping it in hot water enhances the effect because the hot metal increases the rate of dry ice sublimation.
How the Singing Spoon Works
The singing spoon’s “song” comes from rapid pressure oscillations. Reeds in woodwind musical instruments produce sound basically the same way. Similarly, pressure oscillations cause the sizzle of water droplets flicked onto a hot pan.
The metal of the spoon is a good thermal conductor. So, when you press it against the dry ice it imparts of lot of thermal energy. This increases the rate of dry ice sublimation, which is the phase change from solid carbon dioxide directly into carbon dioxide gas. Gas pressure pushes the spoon away from the dry ice. According to Bernoulli’s principle, increasing the rate of gas flow decreases its pressure. As pressure decreases, the spoon drops back onto the dry ice surface. Meanwhile, carbon dioxide flows around the spoon at varying speeds. The pressure changes occur so rapidly that the oscillation makes an audible sound.
The Screaming Coin
A related dry ice project is the screaming coin. Put on gloves or use a dish towel to insulate your hands. Press a quarter or other coin into a chunk of dry ice. Does the coin continue to scream if you simply set it on top of the dry ice? (The answer is yes, but it’s not as loud.)
Turn It Into an Experiment
Once you observe the singing spoon in action, turn it into a science experiment. Using your observations, make predictions about what will happen if you make changes to the project. Test your hypothesis with an experiment.
- What happens if you change the composition of the spoon? For example, how well does a wooden spoon sing? See if you can explain your results. Hint: Consider the thermal conductivity of different materials.
- On a related “note,” do spoons made of different metals sing with the same pitch?
- Does the shape of the metal have an effect? Hint: Changing shape may change surface area in contact with the dry ice.
References
- Batchelor, G.K. (2000). An Introduction to Fluid Dynamics. Cambridge: Cambridge University Press. ISBN 978-0-521-66396-0.
- Häring, Heinz-Wolfgang (2008). Industrial Gases Processing. Christine Ahner. Wiley-VCH. ISBN 978-3-527-31685-4.
- Housecroft, Catherine; Sharpe, Alan G. (2001). Inorganic Chemistry. Harlow: Prentice Hall. ISBN 978-0-582-31080-3.