What Happens When You Freeze Water in a Container That Won't Let It Expand

Natural environments often allow water to expand as it freezes, but what happens when water is confined in a container that does not permit this expansion? This article explores the consequences of freezing water in tightly sealed containers and the resulting physics behind container failure and altered freezing behavior.

Introduction to Water Expansion During Freezing

Water typically expands by about 9% as it freezes. This volume increase is significant and poses a challenge when trying to contain it in a rigid, non-expanding container. In natural settings, this expansion would be allowed, and no harm would come to the water or its surrounding environment. However, in closed containers, the situation can be quite different.

Pressure Increase and Container Failure

When the expansion of freezing water is prevented by a rigid container, the pressure within the container significantly increases. This pressure increase can lead to several adverse effects:

Pressure Increase: Water expands by about 9% when it freezes. In a sealed container, this expansion exerts a tremendous amount of pressure. As an example, the pressure generated by frozen water can be as high as 25,000 psi (pounds per square inch) and can even reach over 100,000 psi if the freezing process continues long enough. Container Failure: The strength of the container material plays a crucial role in determining whether it will withstand this pressure. Glass containers are particularly susceptible to failure due to their brittle nature, but metal and plastic containers can also be affected. If the pressure exceeds the material's strength, the container may crack, break, or even explode. Incomplete Freezing: In some cases, even if the container is strong enough, the water may not freeze completely due to the pressure. This can result in a supercooled state where the water remains liquid even below 0°C (32°F), an unusual phenomenon that can arise due to the extreme pressure.

Phase Changes in Extremely Pressured Water

Under extremely high pressures, water can undergo phase changes that are not typical of regular freezing. These changes can lead to the formation of different solid forms such as ice II or ice III, which have different structures and properties compared to regular ice.

Practical Examples and Experiences

Practical examples and experiences support the theoretical understanding of these phenomena:

A rigid plastic bottle filled with water and frozen can result in the lid being blown off. Despite the strength of the plastic, the pressure generated by the expanding water can be too much to contain. Working with alcohol or beer in tightly sealed containers can also demonstrate similar effects. Even with strong, tight seals, the pressure built up during the freezing process can lead to container failure. Mathematically, the pressure generated by frozen water in a sealed container can be as high as 30,000 pounds per square inch (psi). This pressure can only be absorbed by the container or the air space around the liquid. If the air space is filled with water, the likelihood of the container rupturing is extremely high.

Conclusion

Freezing water in a container that prevents its natural expansion results in significant pressure increases that can lead to container failure and altered freezing behavior. Understanding these phenomena is crucial for designing appropriate containers and preventing accidents in various applications, from everyday household use to industrial processes.