caption: Phase diagram Phase diagram - combinations of temperature, pressure or composition for which specific phases exist at equilibrium.
exif: {"Image DocumentName": "Phase diagram Phase diagram - combinations of temperature, pressure or composition for which specific phases exist at equilibrium.", "Image ImageDescription": "H2O: diagram shows temperature and pressure at which ice (solid),water (liquid) and steam (gas) exist. Both the critical points are shown as red circles. The critical point and the orange line in the ice-one phase space refer to the low-density and. high-density forms of amorphous water (ice). All the solid phases of ice involve the oxygen atoms being hydrogen bonded to four. neighboring oxygen atoms. The high pressure phase lines of ice-ten (X) and ice-eleven (XI) are still subject to experimental verification. Two. different forms of ice-eleven have been described by different research groups: the high-pressure form involves hydrogen atoms equally-spaced. between the oxygen atoms (like ice-ten) whereas the lower pressure low temperature form utilizes the incorporation of hydroxide defect. doping to order the hydrogen bonding of ice 1h. Another ice-ten has been described, being the proton ordered form of ice-six (VI) occurring. below about 110 K. Only hexagonal ice-one (1h), ice-three (III), ice-five (V), ice-six (VI) and ice-seven (VII) can be in equilibrium with liquid water, whereas all the others ices, including ice-two (II), are not stable in its presence under any conditions of temperature and pressure. Ice-two, ice-eight (VIII), ice-nine (IX), ice-ten and ice-eleven (both) all possess (ice-nine mainly) ordered hydrogen-bonding whereas in the other ices. the hydrogen-bonding is disordered even down to 0 K, where reachable. Ice-four (IV) and ice-twelve (XII) [81] are both metastable within the. ice-five phase space. Cubic ice (1c) is metastable with respect to hexagonal ice (1h). It is worth noting that the water molecule is stable. throughout the phase space above. Kurt Vonnegut s highly entertaining story concerning an (imaginary) ice-nine, which was capable of. crystallizing all the water in the world [K. Vonnegut, Cat s Cradle, (Penguin, London, 1963) p. 34.], fortunately has no scientific basis (see also IE) as ice-nine, in reality, is a proton ordered form of ice-three, only exists at very low temperatures and high pressures and cannot exist alongside liquid water under any conditions. Ice 1c is a metastable form of ice that can be formed, by condensation of water vapor, at ambient pressure but low temperatures (less than. -80\u00b0C, see Phase Diagram) or by reducing the pressure on high-pressure ices at 77 K. It converts, irreversibly but extremely slowly in the. temperature range K, to hexagonal ice with about 40 J mol-1 heat evolution. It consists of a face centered cubic lattice (Space. group Fd3m) with half the tetrahedral holes filled.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}