When you freeze carbonated water, it undergoes a series of physical changes that can lead to significant pressure buildup and potentially cause its container to break or even explode. This happens due to a combination of the water expanding as it freezes, the carbon dioxide separating from the solution, and the altered freezing point of the mixture.
The Science Behind Freezing Carbonated Water
Freezing carbonated water is more intricate than freezing pure water because of its dissolved gases and other solutes.
Freezing Point Depression
Carbonated water, like club soda, contains dissolved carbon dioxide (CO2) and often other minerals. These dissolved substances act as solutes, lowering the freezing point of the water. This phenomenon is known as freezing point depression, a colligative property where the freezing point of a solvent decreases as more solute is added. For example, the freezing point of club soda is about –10 °C (14 °F), significantly lower than pure water's 0 °C (32 °F).
Volume Expansion of Water
A unique characteristic of water is that it expands when it transitions into ice, increasing its volume by approximately 9%. This expansion exerts considerable pressure on any container it occupies.
Carbon Dioxide Behavior
As the water begins to freeze, the dissolved carbon dioxide becomes less soluble in the colder, solidifying water. This forces the CO2 gas out of solution, forming bubbles. If the carbonated water is enclosed in a sealed container, this released CO2 gas has nowhere to escape, thereby increasing the internal pressure dramatically.
Risks and Safety Concerns
The combined effects of water expanding and CO2 gas being released create a hazardous situation in a sealed container:
- Immense Pressure Buildup: The expanding ice and the escaping CO2 gas exert tremendous pressure on the container walls.
- Container Damage: This pressure can easily cause plastic bottles to bulge, deform, and eventually burst, or lead to glass bottles shattering into sharp fragments.
- Explosion Risk: In severe cases, especially when sealed carbonated water freezes significantly below its normal freezing point (e.g., a sealed bottle freezing to –10 °C or colder), the drastic change in volume from the freezing process can cause the bottle to break, possibly even explode, posing a serious safety risk.
To prevent such dangerous incidents, it is critical to keep any sealed carbonated water above its specific freezing point, such as –10 °C for club soda.
Practical Implications and Tips
Freezing carbonated water is generally not advisable for consumption or long-term storage in sealed containers.
Here are some practical insights:
- Avoid Freezing Sealed Carbonated Drinks: Never place sealed cans or bottles of soda, sparkling water, or other carbonated beverages in a freezer. They are highly likely to burst.
- Loss of Fizz: If carbonated water is frozen and then thawed, it will have lost much, if not all, of its fizziness because the CO2 gas escapes during the freezing process.
- "Slushy" Effect (Open Container): If you partially freeze carbonated water in an open container, you might achieve a slushy consistency where some ice crystals form, but much of the CO2 will still be lost to the atmosphere.
- Making Carbonated Ice (Not Recommended for Sealed Containers): To make carbonated ice cubes (though much fizz is lost), you would need to freeze the water in an open ice tray to allow the CO2 to escape safely without building pressure.
| Feature | Pure Water | Carbonated Water (e.g., Club Soda) |
|---|---|---|
| Freezing Point | 0 °C (32 °F) | ~-10 °C (14 °F) |
| Volume Change on Freezing | Expands by ~9% | Expands significantly, plus CO2 gas volume |
| Gas Release | None | CO2 gas separates and expands |
| Container Risk (Sealed) | Bottle may break due to expansion | Bottle likely breaks/explodes |
| Thawed State | Returns to liquid water, unchanged | Returns to liquid, loses fizziness |
