Turtles Teach: What is Dry Ice?

Known for its spooky fog and subzero temperatures, dry ice is a mysterious and fascinating substance… but what is it?

dry ice

Everything is made of matter. Matter can exist in many states: solid, liquid, or gas. For instance, water can be liquid, solid (ice), or a gas (vapor or steam). We can change the state of matter by changing the environment that matter is in. You may know we can change water’s state just by changing the temperature. To make water into ice, we freeze it! To make water into a gas, we boil it! However, temperature is not the only factor that determines a substance’s state. Pressure is just as important. Water can be in all three states in normal pressure (1 atmosphere or 14.7 psi); this is not the case with dry ice.

Dry Ice is not made with water, but carbon dioxide. You may know carbon dioxide as a gas, the gas we exhale when we breathe. It too can freeze and change into a solid, but our freezers at home can’t do the job. Special factories use extremely low temperatures and high pressure just to make it. The extremely cold and pressurized carbon dioxide is brought to normal pressures and will solidify into dry ice. This ice is -109 degrees F. But what makes dry ice so fascinating is its ability to sublimate (Sublimation is when matter changes from a solid to a gas). At normal pressure, dry ice cannot be a liquid. When it “melts” it turn directly into carbon dioxide gas! You may see the fog that comes from its icy surface, but carbon dioxide is a clear and colorless gas that we can’t see… The fog is actually the result of water vapor in the air condensing from the cold gas, similar to your warm breath meeting the icy cold air during the winter. When dry ice is added to water, the carbon dioxide gas bubbles up to the surface quickly making the water look like its boiling.

Matter comes in all shapes, sizes, colors, temperatures, and states! Dry ice is just one of the cooler substances.

Hope you learned something new, from your favorite educators at Turtle Bay!