Will a Frozen Soda Can Explode?

Why Frozen Soda Can Burst: Core Principles

A frozen soda can can explode because water expands when it turns to ice and carbon dioxide gas cannot escape. As the liquid freezes, it takes up more volume, while continued carbonation pressurizes the can. When internal pressure surpasses the can’s burst strength, the can fails—often with a split seam or ruptured top. This is a combination of rigid-container failure and the basic behavior of gases and liquids under temperature change.

Physics of Freezing and Pressure Build-up

Water Expansion During Freezing

Water expands about 9% in volume when it freezes. In a sealed can, this expansion happens in a confined space, so pressure begins to rise even before gas effects are significant. The rigid aluminum can resists this expansion, so the energy is stored elastically in the can walls until something gives.

Carbon Dioxide Behavior at Low Temperature

Carbon dioxide is highly soluble in water at low temperatures, which can initially reduce gas volume. However, as temperatures approach the freezing point of the liquid contents, dissolved CO2 may come out of solution, adding to the gas-phase volume. The net effect in typical freezer conditions is increased pressure from both expanding ice and elevated gas pressure.

Pressure-Temperature Relationships

Using the ideal gas approximation, pressure is roughly proportional to absolute temperature when volume and moles of gas are fixed. Cool a gas inside a rigid container from 20°C (293 K) to −18°C (255 K) and pressure drops, but freezing water’s expansion and outgassing can counteract or exceed this effect, leading to net pressure rise.

Can Strength and Failure Modes

Burst Pressure Threshold

Aluminum beverage cans are designed to withstand pressure differences, but they have limits. Typical pull-tab cans have a burst strength in the range of 150–200 psi (absolute), but many factors reduce the effective limit. Seams, rim, and neck thickness are often the weakest points. In practice, frozen cans often fail at much lower pressures due to material brittleness and uneven stress.

Failure Patterns

• Split along the vertical seam, because bending stress concentrates there.
• Pop-top or ring-pull fracture when ice expansion pushes upward against a rigid lid.
• Punctures or tears near the body if pressure rises rapidly.

Material Effects at Low Temperature

Cold can make aluminum more brittle, lowering resistance to crack propagation. A can that might survive minor pressure spikes at room temperature can rupture more easily when frozen.

Practical Risks: When Is It Most Likely?

• Long freezing times in a standard home freezer increase pressure build-up.
• Nearly full cans leave less air space, so ice expansion directly increases pressure rather than being accommodated by a gas cushion.
• Rapid freezing can create localized stresses as ice forms unevenly.

While a frozen soda can can explode, it rarely does so with high energy in typical home settings; most events result in a split seam or bent ring rather than a violent rupture. Still, unexpected can failure can cause mess and minor injury, so prevention is reasonable.

How to Thaw Safely and Prevent Explosions

Step-by-Step Safe Thawing

1. Place the frozen can in a refrigerator or cool area above freezing.
2. Allow gradual warming; do not use direct heat or hot water.
3. Open cautiously after it returns to liquid and pressure equalizes.

Prevention Tips

• Don’t leave soda in the freezer for more than a few hours.
• Leave a small air gap in the can if you must chill it quickly.
• Inspect cans with bulges, leaks, or distorted seams; discard them.

Key Takeaways at a Glance