No, you cannot "refreeze" dry ice in the conventional sense of freezing a liquid back into a solid. Dry ice is already in its solid form, which is frozen carbon dioxide (CO2).
Why You Can't "Refreeze" Dry Ice
The confusion likely stems from thinking about refreezing water ice. With water, you're transitioning between liquid and solid states. However, dry ice undergoes a process called sublimation. This means it transforms directly from a solid into a gas without passing through a liquid phase at standard atmospheric pressure.
- Sublimation: At temperatures above -109.3°F (-78.5°C), dry ice sublimates. Even a freezer, which is typically around 0°F (-18°C), is far too warm to prevent this.
- No Liquid Phase: Because dry ice sublimates, there's no liquid to "refreeze." It simply shrinks as it turns into carbon dioxide gas.
- Safety Concerns: Attempting to contain the sublimating CO2 in a completely sealed container is dangerous. The pressure buildup could lead to an explosion.
What Happens When You Store Dry Ice in a Freezer?
When you place dry ice in a freezer, it will:
- Sublimate: Gradually turn into carbon dioxide gas.
- Cool the Freezer: Help maintain a lower temperature in your freezer for a limited time.
- Disappear: Over time, the dry ice will completely disappear as it sublimates.
Proper Handling of Dry Ice
- Ventilation: Always handle dry ice in a well-ventilated area to prevent carbon dioxide buildup, which can be harmful.
- Insulation: Store dry ice in an insulated container to slow down the sublimation process. However, do not seal the container completely.
- Protection: Wear gloves and eye protection when handling dry ice to avoid frostbite.
Summary
Dry ice cannot be "refrozen" because it sublimates directly from a solid to a gas. Storing it in a freezer will only slow down the sublimation process, but the dry ice will eventually disappear. Always handle dry ice with caution and in a well-ventilated area.
