Zero Liquid! The Science of Dry Ice Vanishing Over 3 Hours — Sublimation, Condensation & Uniform Motion

I’m Ken Kuwako, your science trainer. Every day is an experiment.

Have you ever watched dry ice quietly vanish while releasing a mysterious fog? It never turns into liquid—just disappears straight into gas. It almost feels like magic. But hidden inside this “not-so-ordinary” change are fascinating laws of physics and chemistry. This time, I used leftover dry ice from a cloud chamber radiation experiment to try out a few fun demonstrations.

A Time-Lapse Look at Sublimation

First, I recorded the sublimation of dry ice using time-lapse photography. I used a 1 kg block and filmed it for three hours—but surprisingly, it didn’t completely disappear! Here’s a 90-second version of that three-hour process.

In the video, you can see something like white smoke forming around the dry ice. This isn’t the dry ice itself turning into visible gas (carbon dioxide). Instead, it’s water vapor in the air cooling and condensing into tiny droplets or ice particles. It’s the same reason your breath turns white on a cold winter morning. For comparison, I placed regular ice next to it.

Initial state

Regular ice gradually melts, but dry ice lives up to its name—it stays dry. No liquid appears.

Regular ice changes from solid → liquid (water) → gas (water vapor). Dry ice, however, jumps directly from solid → gas (carbon dioxide), skipping the liquid phase entirely. This process is called sublimation. Now the name “dry ice” makes perfect sense.

Gliding Across the Table—A Carbon Dioxide Air Cushion

Next, I tried sliding dry ice across a table.

When you place dry ice on a table, carbon dioxide gas escapes from underneath due to sublimation, causing it to vibrate rapidly. That gas forms a cushion between the dry ice and the surface, allowing it to glide smoothly.

This motion is perfect for observing uniform straight-line motion. With almost no friction, the object continues moving at a constant speed without any additional force—this is Newton’s First Law (the law of inertia) happening right before your eyes. This principle is also used in factories for moving heavy objects and even in air hockey tables.

Shaking Scissors—and the Birth of a Cloud

When I placed a pair of scissors on top of the dry ice, something interesting happened. The scissors began to rattle and shake. This happens because the carbon dioxide gas pushing up from below repeatedly lifts and drops them. Around the dry ice, you can also see a white cloud forming. This is caused by water vapor in the air cooling and condensing—exactly the same mechanism that creates real clouds. The thicker cloud below likely forms because the gas is being pushed out more forcefully in that direction.

Drop It in Water—A Cloud Explosion

Finally, I placed the dry ice in water. As soon as it hits the water, the sublimation speed increases dramatically, producing huge amounts of thick white fog. This happens because water transfers heat to the dry ice, accelerating the process. This is the same principle often used in stage performances and movies to create dramatic fog effects. Science is quietly working behind the scenes of everyday entertainment.

If you ever get your hands on some dry ice, give these experiments a try. Sublimation, condensation, uniform motion—concepts from textbooks suddenly come alive right in front of you.

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５月のイチオシ実験！

キーンと冷えるドライアイス！気温が上がってくるこの時期・ドライアイスを使った昇華・凝結・等速度直線運動の実験はいかが？

液体ゼロ！ドライアイスが消えるまでの３時間を科学する（昇華・凝結・等速度直線運動）

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