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Why does water not freeze at 0 degrees?

At zero degrees, water and ice are in a state of thermodynamic equilibrium. Water molecules are released from the ice, while at the same time, ice molecules are formed from the water. Celler now adds a bit of table salt to the bowl and stirs. The temperature drops, but look at this, the water doesn't freeze.



While 0∘C (32∘F) is the standard freezing point of water, it does not always freeze at this temperature due to factors like purity, pressure, and solutes. One common reason is "supercooling," which occurs in very pure water that lacks "nucleation centers" like dust or impurities. Without these tiny particles to act as a starting point for ice crystals to form, water can remain liquid down to −40∘C. Another factor is solute interference, such as the "Freezing Point Depression" caused by salt. When salt is dissolved in water, it disrupts the ability of water molecules to bond into a solid crystalline structure, which is why seawater freezes at a lower temperature (around −2∘C) than fresh water. Additionally, high pressure can lower the freezing point, as it makes it harder for water molecules to expand into the less-dense structure of ice. Finally, water in motion (like a fast-moving river) or water under constant vibration may resist freezing at 0∘C because the physical agitation prevents the stable formation of the initial ice lattice. These scientific nuances are why "freezing rain" exists and why adding antifreeze to a car's radiator prevents the engine block from cracking in winter.

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