Search results
Results from the WOW.Com Content Network
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.
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 .
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Molecular solids have low melting (T m) and boiling (T b) points compared to metal (iron), ionic (sodium chloride), and covalent solids (diamond). [4] [5] [8] [13] Examples of molecular solids with low melting and boiling temperatures include argon, water, naphthalene, nicotine, and caffeine (see table below).
When a solid is heated above its melting point, it becomes liquid, given that the pressure is higher than the triple point of the substance. Intermolecular (or interatomic or interionic) forces are still important, but the molecules have enough energy to move relative to each other and the structure is mobile.
Solid hydrogen is the solid state of the element hydrogen. At standard pressure , this is achieved by decreasing the temperature below hydrogen's melting point of 14.01 K (−259.14 °C; −434.45 °F).
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 ...
At the boiling point of hydrogen with excess solid nitrogen, the dissolved molar fraction is 10 −8. At 32.5 K (just below the boiling point of H 2) and 15 atm, the maximum molar concentration of dissolved N 2 is 7.0 × 10 −6. [15] Nitrogen and oxygen are miscible in liquid phase but separate in solid phase.