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The phases of ice are all possible states of matter for water as a solid. Variations in pressure and temperature give rise to different phases, which have varying properties and molecular geometries. Variations in pressure and temperature give rise to different phases, which have varying properties and molecular geometries.
The phase transition from solid to liquid is achieved by mixing salt and water molecules, similar to the dissolution of sugar in water, even though the water temperature is far below the melting point of the sugar. However, the dissolution rate is limited by salt concentration and is therefore slower than melting.
The term phase is sometimes used as a synonym for state of matter, but it is possible for a single compound to form different phases that are in the same state of matter. For example, ice is the solid state of water, but there are multiple phases of ice with different crystal structures, which are formed at different pressures and temperatures.
Solid: A solid holds a definite shape and volume without the need of a container. The particles are held very close to each other. Amorphous solid: A solid in which there is no far-range order of the positions of the atoms. Crystalline solid: A solid in which atoms, molecules, or ions are packed in regular order.
In elements, this is known as allotropy, whereas in compounds it is known as polymorphism. The change from one crystal structure to another, from a crystalline solid to an amorphous solid, or from one amorphous structure to another (polyamorphs) are all examples of solid to solid phase transitions.
A typical phase diagram for a single-component material, exhibiting solid, liquid and gaseous phases. The solid green line shows the usual shape of the liquid–solid phase line. The dotted green line shows the anomalous behavior of water when the pressure increases. The triple point and the critical point are shown as red dots.
Aside from common hexagonal crystalline ice, other crystalline and amorphous phases of ice are known. The gaseous phase of water is known as water vapor (or steam). Visible steam and clouds are formed from minute droplets of water suspended in the air. Water also forms a supercritical fluid.
Methane clathrate block embedded in the sediment of hydrate ridge, off Oregon, USA. Clathrate hydrates, or gas hydrates, clathrates, or hydrates, are crystalline water-based solids physically resembling ice, in which small non-polar molecules (typically gases) or polar molecules with large hydrophobic moieties are trapped inside "cages" of hydrogen bonded, frozen water molecules.