<s>[INST] when you put a water bottle into a freezer, an let it sit there without touching it, sometimes it will still be water but when you disturb it it will freeze all at once. why does that happen? [/INST] When the bottle is left undisturbed, the ice crystals that form on the outside can act as nucleation sites, which are small areas where the freezing process can begin. However, these nucleation sites may not be enough to start the freezing process throughout the entire bottle of water.

When you disturb the bottle, you're introducing more nucleation sites, which will cause the remaining liquid water to freeze all at once. This is due to the fact that the agitation causes the movement of the liquid and the introduction of more nucleation sites, which will allow the freezing process to continue throughout the entire bottle.</s>\ <s>[INST] What's a nucleation site? [/INST] A nucleation site is a microscopic irregularity that helps molecules aggregate, in this case forming ice crystals. Another example would be the famous Mentos in Coke experiment, where the rough surface of the Mentos helps bubbles of CO₂ to form.</s>