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Why did my five gallon water bottle freeze before my eyes when we brought it inside to stop it from freezing. It formed star like ice crystals that spread to the bottom in less than a minute! The bottles had spent the night outside during a deep freeze for this area. Two froze outside and two froze in the house. How did that happen?
Question Date: 2004-01-11
Answer 1:

This is a very difficult question to answer. I discussed it with a few of my chemistry friends and it seems the only close reason for this situation is from super cooling. This situation would be if the liquid came into contact with a catalyst which caused a reaction making the liquid freeze instantly. This catalyst could have been on the wall of bottle and when the bottle was moved it came into contact with the water. I hope this helps.

Answer 2:

Here is what happened:
When you cool down a liquid, at a certain temperature it will freeze (freezing temperature or freezing point). But freezing implies the formation of crystals out of the liquid phase. The molecules of a liquid will not order themselves easily to form the solid crystal, even if they have slowed down enough (that is, even if the temperature has fallen below the freezing point).
The appearance of a crystal in the liquid phase, a process called nucleation, always requires a solid surface with some roughness where the first crystal seeds can form. Once the "seeds" have formed, the formation of the crystalline mass can happen amazingly fast. Any process that brings a rough surface in contact with the liquid can help the nucleation and crystallization.
Scratching the internal walls of the container often helps, stirring can bringing into the liquid phase dust particles from the air surrounding the liquid. Also intentionally adding a very tiny crystal will produce the desired effect.
A liquid in the state of water in your bottle when you brought it in is said to be "undercooled". Any dust particle falling on it is generally enough to bring about the phenomenal growth of ice crystals as you could observe.
Very nice crystals formed, weren't they?
There is also a very similar phenomenon that happens when you dissolve too much solid into a liquid solution. The solution can go to a state of "supersaturation", and that means that it contains more solute than it should according to the solubility of the solid and the working temperature. If in that solution you put a tiny piece of the solid solute, most of the times you will get the formation of large amount of crystals in a very short time.

I hope you understand now all about undercooling and supersaturation, but if you need further explanations, let me know.

Answer 3:

You have observed a phenomenon called nucleation. Sometimes, you can cool water below its freezing point and it still will not freeze. However, in such a condition, it is not stable and any little help you provide (such as shaking the water when you move it) is enough to make it freeze --- you nucleate the freezing.
It is like having a carefully balanced ball right at the top of a small hill. Any little touch and the ball will roll.

Answer 4:

The water in the jugs that didn't freeze was probably super-cooled. In this case, they froze not because you brought them inside but because you physically moved them, and the water was ready to crystallize at the slightest movement.
Since ice is a crystal, it needs some nucleus or other imperfection to form. The molecules in the water also have to move to aggregate themselves to form ice crystals. If you have liquid water, that is left perfectly still, it can be cooled down to very low temperatures - well below the normal freezing point - and yet stay liquid.
The moment the water is jostled, however, some of the molecules will find themselves aggregated into the future crystal structure.
Once a crystal forms, it causes other molecules to form the crystal with it, so the crystals grow amazingly fast.

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