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The Mpemba effect is the name given to the observation that a liquid (typically water) that is initially hot can freeze faster than the same liquid which begins cold, under otherwise similar conditions. There is disagreement about its theoretical basis and the parameters required to produce the effect.
Regular, hexagonal ice is also less dense than liquid water—upon freezing, the density of water decreases by about 9%. [36] [e] These peculiar effects are due to the highly directional bonding of water molecules via the hydrogen bonds: ice and liquid water at low temperature have comparatively low-density, low-energy open lattice structures.
Once agitated it will rapidly become a solid. During the final stage of freezing, an ice drop develops a pointy tip, which is not observed for most other liquids, and arises because water expands as it freezes. [10] Once the liquid is completely frozen, the sharp tip of the drop attracts water vapor in the air, much like a sharp metal lightning ...
Most liquids under increased pressure freeze at higher temperatures because the pressure helps to hold the molecules together. However, the strong hydrogen bonds in water make it different: for some pressures higher than 1 atm (0.10 MPa), water freezes at a temperature below 0 °C.
Liquid water can be assumed to be incompressible for most purposes: ... Mpemba effect – Natural phenomenon that hot water freezes faster than cold;
This is analogous to water dripping in the back of an overcooled refrigerator and freezing when it hits the shelf. That ice builds up on the shelf until either the fridge warms up or you chip away ...
Liquid water and ice emit radiation at a higher rate than water vapour (see graph above). Water at the top of the troposphere, particularly in liquid and solid states, cools as it emits net photons to space. Neighboring gas molecules other than water (e.g. nitrogen) are cooled by passing their heat kinetically to the water.
Liquid water is densest, essentially 1.00 g/cm 3, at 4 °C and begins to lose its density as the water molecules begin to form the hexagonal crystals of ice as the freezing point is reached. This is due to hydrogen bonding dominating the intermolecular forces, which results in a packing of molecules less compact in the solid.