To know the basics the a one-component phase diagram together a role of temperature and also pressure in a closeup of the door system. To be able to identify the triple point, the crucial point, and also four regions: solid, liquid, gas, and a supercritical fluid.

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The state displayed by a provided sample of issue depends on the identity, temperature, and also pressure the the sample. A phase diagram is a graphic an introduction of the physics state the a substance as a function of temperature and also pressure in a close up door system.


A typical phase diagram consists of discrete regions that represent the various phases showed by a substance (Figure (PageIndex1)). Each region corresponds to the range of combinations of temperature and pressure over which the phase is stable. The combination of high pressure and low temperature (upper left of figure (PageIndex1)) coincides to the heavy phase, conversely, the gas phase is favored in ~ high temperature and low pressure (lower right). The mix of high temperature and also high push (upper right) corresponds to a supercritical fluid.

Figure (PageIndex1): A usual Phase Diagram because that a Substance the Exhibits three Phases—Solid, Liquid, and Gas—and a Supercritical Region

The solid phase is favored at short temperature and also high pressure; the gas phase is favored at high temperature and low pressure.

The phase Diagram the Water

Figure (PageIndex2) reflects the step diagram of water and also illustrates that the triple allude of water occurs at 0.01°C and 0.00604 atm (4.59 mmHg). Far more reproducible 보다 the melting point of ice, which counts on the lot of liquified air and also the atmospheric pressure, the triple point (273.16 K) is supplied to define the pure (Kelvin) temperature scale. The triple allude also represents the lowest pressure at which a fluid phase have the right to exist in equilibrium through the heavy or vapor. At pressures much less than 0.00604 atm, therefore, ice does no melt to a liquid together the temperature increases; the heavy sublimes directly to water vapor. Sublimation of water at low temperature and pressure have the right to be offered to “freeze-dry” foods and also beverages. The food or beverage is an initial cooled come subzero temperatures and also placed in a container in i beg your pardon the push is maintained below 0.00604 atm. Then, as the temperature is increased, the water sublimes, leave the dehydrated food (such together that supplied by backpackers or astronauts) or the powdered beverage (as with freeze-dried coffee).


Exercise (PageIndex2)

Referring to the step diagram that water in figure (PageIndex2), suspect the physical kind of a sample that water in ~ −0.0050°C as the pressure is slowly increased indigenous 1.0 mmHg to 218 atm.

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The sample is originally a gas, condenses to a solid as the press increases, and then melts as soon as the press is increased more to offer a liquid.