Dry Ice Floating Bubbles

1. Pour warm water into a large, clear plastic bowl until about an inch of warm water covers the bottom of the bowl.
2. Use gloves or tongs to add a few pieces of dry ice to the warm water in the bowl. Take a second to observe the effect that is created when warm water and dry ice mix.
3. Using a bubble wand and some bubble solution, blow a few bubbles into the bowl. It can be a bit difficult, so be patient!
4. Once you get a bubble into the bowl, what happens? The bubbles float on the sea of smoke!
    

How does it work?

You noticed that when you added dry ice to the water, a cloud of carbon dioxide and water was produced. But unlike smoke from a candle or fire, the dry ice smoke doesn't float. Instead, it settles onto the ground or, in this case, on top of the water. Why is that? The smoke is actually a combination of carbon dioxide gas and water vapor. This gaseous dry ice smoke is heavier than the air around it, so it sinks in the air rather than rising.

The same relation between air and dry ice smoke explains why the bubbles float on top of the dry ice smoke. The air exhaled into the bubble is less dense than the gases comprising the dry ice smoke, but slightly heavier than the air surrounding the bubble. So although the bubble doesn't float in the air, it does float on the heavier dry ice smoke.