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The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
The melting point of ordinary hexagonal ice falls slightly under moderately high pressures, by 0.0073 °C (0.0131 °F)/atm [h] or about 0.5 °C (0.90 °F)/70 atm [i] [53] as the stabilization energy of hydrogen bonding is exceeded by intermolecular repulsion, but as ice transforms into its polymorphs (see crystalline states of ice) above 209.9 ...
For pure elements or compounds, e.g. pure copper, pure water, etc. the liquidus and solidus are at the same temperature, and the term melting point may be used. There are also some mixtures which melt at a particular temperature, known as congruent melting. One example is eutectic mixture. In a eutectic system, there is particular mixing ratio ...
Most of the defined points are based on a phase transition; specifically the melting/freezing point of a pure chemical element. However, the deepest cryogenic points are based exclusively on the vapor pressure /temperature relationship of helium and its isotopes whereas the remainder of its cold points (those less than room temperature) are ...
Freezing is a phase transition in which a liquid turns into a solid when its temperature is lowered below its freezing point. [ 1 ] [ 2 ] For most substances, the melting and freezing points are the same temperature; however, certain substances possess differing solid-liquid transition temperatures.
Below that temperature, but above the freezing point of 0 °C (32 °F), it expands becoming less dense until it reaches freezing point, reaching a density in its liquid phase of 999.8 kg/m 3 (62.4155 lb/cu ft). Once it freezes and becomes ice, it expands by about 9%, with a density of 917 kg/m 3 (57.25 lb/cu ft).
Melting ice cubes illustrate the process of fusion. Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which increases the substance's temperature to the melting point.
This Wikipedia page provides a comprehensive list of boiling and freezing points for various solvents.