[jarnacle (OP)]

I recently thought of a nice way of explaining why supercooled liquid crystalizes instantly. At least, I think I thought of it. That’s partially why I am posting this. I want you chumps to fact check me and tell me if somebody already thought of this.


Note To Reader: I'm a physics student, this might be wrong. I’m working on my first youtube video, it will be a more in depth and general explanation of this concept. This is a test to see how much anybody cares. I’m sorry if this wasted your time haha.

Liquids and gases (called fluids when referring to each at the same time) are composed of molecules constantly running around and bumping into each other (which is why they freely move around), while solids are composed of molecules locked into place with each other, vibrating and surrounded on all sides by the other atoms of the solid. All things can change from fluids to solids (and back again) depending on the temperature of their environment. This means that temperature changes the speed of molecules in fluids. Colder temperatures result in slower moving fluids, meaning for a liquid to turn into a solid, it must first be at a temperature where all of its molecules are not moving.

When a fluid turns into a solid, all of its molecules arrange themselves in a very orderly way, especially when you compare them to how they were randomly arranged in the fluid previously. We call this process freezing. A freezer is named because it is cold enough to freeze water. If we leave a bottle of water in there long enough it will become the temperature of the freezer, which is somewhat colder than freezing. Meaning the water will be at a temperature even colder than the temperature at which liquid water molecules do not move. However as you clearly know the water in the bottle remains a liquid.


Think about the process of rearrangement: it requires movement. If your room is messy, you have to move things to put them away. Remember when I said that freezing is the process of molecules arranging themselves very orderly, they have to move to do that. That makes things difficult since freezing requires the molecules to also not be moving. If the liquid is shaken however, this fixes that problem. The molecules use the speed they’re given to arrange themselves in an orderly way. They want to do this because they are all little magnets that are attracted to one another.

So then you might be asking why does ice freeze in ice trays in the freezer? The immediate explanation is that the air in your freezer is moving because of fans pumping cold air in. Thus giving the water molecules enough speed to begin freezing. However if you fill a plastic bottle, with pond water (or tap water depending on where you live), screw the cap on and put it in the freezer, it will freeze. This is because water doesn’t very much like having other things swimming around in it. I say this because a foreign object will never stop moving in water. The water molecules can’t get comfortable with anything other than other water molecules, this is because water molecules are little magnets. Foreign objects force individual water molecules closer together in ways that create a magnetic reaction, creating motion. This allows molecules to arrange themselves if they want to freeze.


If you’re this far, thanks. I lied to you guys, sorry. I’m actually gonna be making my first youtube video pretty soon on this analogy. This analogy also applies to the least energy state principle, and the idea of activation energy. My video will go more in depth than text can go into this analogy, with the supercooled water phenomenon only being a minor example in the video.. Any support will be greatly appreciated.

[puppypower]

Water is interesting because water expands when it freezes, which is not very common in nature. The only other natural material that does this is the element Antimony. It is far more common in nature for materials to contract when they freeze. The reason water expands is because of hydrogen bonding.

Hydrogen bonding is a moderately strong secondary bond, that shows both polar and covalent bonding character. The polar bonding aspect is denser, while the covalent bonding aspect is less dense. The expansion observed during freezing is implicit of the polar-covalent balance within the hydrogen bonding of liquid water, slanting more toward the covalent side of the balance. The covalent side defines longer hydrogen bonds, with lower enthalpy and lower entropy, compared to the polar. Both the enthalpy and entropy give off energy, when the covalent switch occurs, during freezing. This accounts for water's high heat of fusion.

Water can be sub cooled; remain a liquid below it's melting point,  quite easily because of the two competing bonding states of its hydrogen bonds. The hydrogen bonds are like binary switches. Since the polar state is denser and has higher entropy, there is resistance to freeze, because of the second law, since the needed shift to the covalent side will lower entropy. One can fool liquid water to maintain itself below it melting point, by flipping the hydrogen bond switch.

If we increase the pressure, and thereby compress the hydrogen bonds of the water in ice, the hydrogen bonds start to move back toward the polar side of the balance, allowing liquid to appear. When ice melts, the shift from covalent to polar/covalent, cause the water to contract as it melts.

Water is at its most dense at 3.98C. This is where the polar aspect is most dominant. Water will expand going in either direction from there. 

There is an anomaly of water that allows hot water to freeze faster than cold water, even though more heat has to be shed. The reason is, since water expands as we heat it, the hydrogen bonding switches are being flipped more to the covalent side. The net affect is the hot water is set up better for the transition to the covalent state needed for freezing. The cold water is denser and is more polar so it resists; supercools, to maintain higher entropy. 

[Bored chemist]

Both the enthalpy and entropy give off energy,

Nonsense

Water can be sub cooled; remain a liquid below it's melting point,  quite easily because of the two competing bonding states of its hydrogen bonds.

Lots of things can be supercooled- mercury for example.
It's nothing to do with hydrogen bonds.

The hydrogen bonds are like binary switches

Not really.

Since the polar state is denser

That's meaningless.

One can fool liquid water to maintain itself below it melting point, by flipping the hydrogen bond switch.

Obviously tosh, because you can do the same with other liquids- even those without hydrogen bonds.

When ice melts, the shift from covalent to polar/covalent,

The covalency does not change.

The reason is, since water expands as we heat it, the hydrogen bonding switches are being flipped more to the covalent side. The net affect is the hot water is set up better for the transition to the covalent state needed for freezing. The cold water is denser and is more polar so it resists; supercools, to maintain higher entropy. 

That's just word salad.

[Slickscientist]

For dunces...

Yours sincerely,
Slickscientist