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Topic: Ice Ih

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	Hexagonal ice structure (Site not responding. Last check: 2007-10-12)
		Hexagonal ice (ice Ih) is the form of all natural snow and ice on Earth (see Phase Diagram), as evidenced in the six-fold symmetry in ice crystals grown from water vapor (i.e.
		The dielectric constant of hexagonal ice is 97.5 [94].
		Hexagonal ice crystals may form by (slowly) growing in the direction of the c-axis (S1 ice) as inside vertical freezing pipes or where ice crystals grow down vertically from crystal platelets nucleated on still water with their c-axes vertical, and where sideways growth is prevented but axial growth allowed.
	www.lsbu.ac.uk /water/ice1h.html (1724 words)

	Ice
		Ice can be formed at higher temperatures in pressurized environments, and water will remain a liquid or gas until -30°C at lower pressures.
		Ice, water and water vapour can coexist at the triple point, which for this system is 273.16K at a pressure of 611.73 Pa.
		The result of this is that ice floats on liquid water, an important factor in Earth's climate.
	www.ebroadcast.com.au /lookup/encyclopedia/ic/Ice_crystals.html (431 words)

	Explaining ice: the answers are slippery
		After all, ice is a solid, and trying to glide on thin metal blades across the surfaces of most solids — concrete, wood, glass, to name a few — results in ear-piercing sounds and ungraceful stumbles.
		That is why ice floats on water, while a cube of frozen alcohol — which has a freezing temperature of minus 173 degrees Fahrenheit — would plummet to the bottom of a glass of liquid alcohol.
		The crystal structure of the ice is fairly loose — the reason that Ice Ih is less dense than liquid water — and the bonds that the hydrogen atoms form between water molecules, called hydrogen bonds, are weaker than most atomic bonds.
	www.universityscience.ie /pages/scimat_Explaining_ice.php (1642 words)

	Phase diagram of water and ice (Site not responding. Last check: 2007-10-12)
		All the crystalline phases of ice involve the water molecules being hydrogen bonded to four neighboring water molecules.
		Cubic ice (Ic) is metastable with respect to hexagonal ice (Ih).
		Ice Ih may be metastable with respect to empty clathrate structures of lower density under negative pressure conditions (i.e.
	www.lsbu.ac.uk /water/phase.html (1264 words)

	Ice Ih - Wikipedia, the free encyclopedia
		increases with decreasing temperature (density of ice at -180 °C is 0.9340 g/cm³).
		The latent heat of melting is 5987 J/mol, and its latent heat of sublimation is 50911 J/mol.
		By contrast, the structure of Ice II is very proton-ordered, which helps to explain the entropy change of 3.22 J/mol when the crystal structure changes to that of Ice II.
	en.wikipedia.org /wiki/Ice_Ih (770 words)

	ICE
		Ice II is a completely proton-ordered phase for which the proton-disordered version is unstable and is not observed.
		Ice Ic is related to ice Ih in the same way as cubic diamond is related to hexagonal diamond, the cubic and hexagonal forms having almost the same density.
		The reorientation of the molecular dipoles in ice is facilitated by the mobility of orientational L and D defects, which are generated by thermal activation.
	skua.gps.caltech.edu /hermann/ice.htm (1983 words)

	Ice
		Ice, it turns out, is a factor in activities as diverse as skiing and skating, rainmaking, polar marine transportation, and cold ocean oil exploration.
		Ice is also a factor in global climate, evident perhaps from the facts that the Antarctic and Greenland ice sheets cover about 10% of the earth's land area and sea ice covers about 10% of the ocean surface either seasonally or perennially.
		Sea ice is characterized also by an intragranular porous substructure that consists of submillimeter diameter air bubbles and brine pockets, totaling 4-5 vol.%, arrayed in a plate-like manner parallel to basal planes.
	users.bigpond.net.au /mickandlucyna/mickstavern/ice.htm (5307 words)

	Dom's Research Interests - water ice
		Ice Ic may be formed by direct condensation of water vapour into the solid state - this apparently occurs in the polar stratosphere - or else it can be formed from other forms of ice (as described in a moment).
		Ice V has a very complex disordered monoclinic structure, and ice VI is tetragonal and disordered, achieving a greater degree of densification by being constructed of two interpenetrating networks of hydrogen-bonded water molecules.
		The effect of having ice shells with different properties is to alter the pattern of convection, and thus the transport of heat, from core to surface.
	www.homepages.ucl.ac.uk /~ucfbanf/water_ice.htm (1445 words)

	SNOW HYDROLOGY (GEOG 4321): ICE PHYSICS
		The hexaganol form known as ice Ih is the only one that is found on the surface of the earth at normal temperatures and pressures.
		In ice, a water molecule has four nearest neighbors to which it is bonded via hydrogen bonds (two from its hydrogen atoms and two from the lone electron pairs on the oxygen).
		Therefore the density of ice Ih is 917 kg/m3, compared with a density of 1,000 kg/m3 for liquid water at 4 degC.
	snobear.colorado.edu /Markw/SnowHydro/mol.html (1962 words)

	Ice - Wikipedia, the free encyclopedia
		Ice also plays a role in winter recreation, in many sports such as ice skating, tour skating, ice hockey, ice fishing, ice climbing, curling and sled racing on bobsled, luge and skeleton.
		Ice scrapers are tools designed to break the ice free and clear the windows, though removing the ice can be a long and labor-intensive process.
		It is troublesome to remove this form of ice, so people often open their windows slightly when the vehicle is parked in order to let the moisture dissipate, and it is now common for cars to have rear-window defrosters to combat the problem.
	en.wikipedia.org /wiki/Ice (2283 words)

	The Physics of Ice (Site not responding. Last check: 2007-10-12)
		The ice we encounter in everyday life is known as ice-I in the Bridgman nomenclature.
		Since the thickest ice sheet in the world - in Antarctica - is less than 4000 m thick, corresponding to a maximum pressure at the base of the ice of about 350 atm, it is clear that none of these artificial ices can normally exist on the earth.'' (Pounder, 1965, p.
		In 1963 Kurt Vonnegut described in his science fiction novel Cat's Cradle the properties of a fictional form of ice, which he called ice IX, which was capable of crystallizing all the water in the world.
	www-2.cs.cmu.edu /~dst/ATG/ice.html (338 words)

	The 3-D structure of Ice using the JMol Applet
		Ice floats because it is less dense than water.
		In ice Ih, each water forms four hydrogen bonds with O---O distances of 2.76 Angstroms to the nearest oxygen neighbor.
		Because of ordered structure in ice there are less H20 molecules in a given space of volume.
	www.edinformatics.com /interactive_molecules/ice.htm (491 words)

	ICE AND ICEBERGS \| WATER H2O HYDROGEN AND OXYGEN \| COKE, COCA, PEPSI, VIRGIN, SOLAR COLA
		Ice Ih is the normal form of ice; ice Ic is formed by depositing vapor at very low temperatures (below 140°K).
		All the solid phases of ice involve the water molecules being hydrogen bonded to four neighboring water molecules.
		The low-temperature ices, ice-two, ice-eight (VIII), ice-nine (IX) and ice-eleven (low pressure form) all possess (ice-nine incompletely) low entropy ordered hydrogen-bonding whereas in the other ices (except ice-ten [80] and ice-eleven where the hydrogen atoms are symmetrically placed) the hydrogen-bonding is disordered even down to 0 K, where reachable.
	www.solarnavigator.net /ice.htm (1062 words)

	Study Suggests the Existence of Ferroelectric Ice in the Universe
		This figure shows the molecular structures of ice XI and ice Ih and plots their existence in the solar system as a function of temperature and distance from the sun.
		Normal ice, which forms all natural snow and ice on Earth, is known to scientists as “ice Ih,” where the 'h' stands for hexagonal, the shape of the molecular crystal.
		In ice Ih, the bonds between the hydrogen and oxygen atoms are oriented randomly, resulting in a crystal that looks fairly messy.
	physorg.com /news83862687.html (995 words)

	Density of Ice
		Ice is the solid phase of water and is usually sustained within temperatures at or below 0 °C. An interesting property of water is that it is less dense in the solid phase (ice) than it is in the liquid phase.
		In theory, ice has had a major effect on evolution and the development of the human species.
		The effect of the density of ice on evolution by Sharon Fenton of Sheffield Hallam University.
	hypertextbook.com /facts/2000/AlexDallas.shtml (383 words)

	materials science 01
		Ice XII is produced at about 0.55 GPa and 260 K. It provides the first example of a four-connected network which is built up by seven- and eight-membered rings
		Ice XII, therefore, is rather prolific in water's phase diagram existing in at least two topologically unconnected regions.
		The study of the formation of ice Ih to ice XII contributes valuable clues to the understanding of water amorphisation under pressure.
	www.ill.fr /AR-99/page/41chemistry.htm (841 words)

	Re: Must freezing water expand?
		At a temperature of 0 Centigrade, we pass from the region labelled "liquid water" into the region labelled "Ih", the name for the familiar form of ice.
		Ice III is more dense than 1 gram/milliliter, so formation of Ice III would probably relieve pressure, permitting Ice Ih to form, so we would end up with a mixture of Ice III and Ice Ih.
		Given that the density of Ice Ih is 0.93 and that of Ice III 1.15, to get an average density of 1 would require a mixture of about 2/3 Ice Ih and 1/3 Ice III.
	www.madsci.org /posts/archives/mar97/859148048.Ph.r.html (340 words)

	Ice-climb Science: how the ice forms, deforms, and fails (via CobWeb/3.1 planetlab2.cs.unc.edu) (Site not responding. Last check: 2007-10-12)
		In ice Ih, the oxygen atoms of the water molecules can be imagined as being arranged in layers of hexagonal rings and the layers are stacked on one another.
		When a single ice crystal is subjected to stress, the region between adjacent rings will slip more readily than a layer will tear, and there is no apparent preferred direction for this slippage –much like a stack of playing cards will readily slip, but it’s tough to tear the deck.
		Where the ice is concave, the force of the tool-strike is directed into the ice, and micro-crack formation is thwarted.
	www.iceclimb.com.cob-web.org:8888 /science.html (2173 words)

	[No title]
		The ice melts with 0°C and water boils with 100°C in constant atmospheric pressure (1 013,25 hPa).
		That led H. Eyring to propose a model where swarms of 48 molecules d’eau having the density of the Ih ice are dispersed in a solvent of quasi crystalline structure (density of ice III).
		While melting, the Ih ice is transformed into quasi crystalline liquid III where appear fluctuating gaps and there is contraction.
	library.thinkquest.org /27627/physiquea3.htm (753 words)

	Computational Studies of a New Ice Polymorph (Site not responding. Last check: 2007-10-12)
		It was determined to be an ice polymorph that has not yet been observed in either experimental or theoretical studies.
		By comparing the free energies of the various polymorphs under common pressure and temperature conditions, we can understand which crystalline phase is thermodynamically preferred for that particular model and thus, which form we would expect it to adopt under unrestricted dynamics.
		It is also a stable polymorph for SPC/E, and the differences of free energy between the various polymorphs that simulation conditions (such as the volume in canonical ensemble simulations) may have an effect in what polymorph is expressed during crystallization.
	www.openscience.org /~chrisfen/imaginaryIce.html (1614 words)

	main
		of heavy ice VI have been grown from the liquid inside the pressure cell at ~0.9 Gpa (9 kbar).
		It is planned to compare the observed atomic probability densities with the results from molecular dynamic simulations in order to test the water-water interaction potentials used in the latter.
		A first comparison indicates that real ice Ih near the melting point is more "crystalline" (i.e.
	www.ill.fr /YellowBook/D9/app1.html (380 words)

	OUP: UK General Catalogue
		Ice is one of the most abundant and environmentally important materials on Earth, and its unique and intriguing physical properties present fascinating areas of study for a wide variety of researchers.
		This book is about the physics of ice, by which is meant the properties of the material itself and the ways in which these properties are interpreted in terms of water molecules and crystalline structure.
		Although ice has a simple crystal structure its hydrogen bonding results in unique properties, which continue to be the subject of active research.
	www.oup.com /uk/catalogue/?ci=9780198518952 (493 words)

	Physical Properties of Ice
		At ordinary pressures the stable phase of ice is called ice I, and the various high-pressure phases of ice number up to ice XIV so far.
		Amorphous ice can be made by depositing water vapor onto a substrate at still lower temperatures.
		Each oxygen atom inside the ice Ih lattice is surrounded by four other oxygen atoms in a tetrahedral arrangement.
	www.its.caltech.edu /~atomic/snowcrystals/ice/ice.htm (494 words)

	ice - ISIS99
		By measuring the temperature dependence of the acoustic phonons in ice using PRISMA, not only were we able to determine which modes are responsible for the negative thermal expansion, but also the point within the Brillouin zone where the effect occurs.
		O ice crystal of approximately one cubic centimetre, which was aligned with its c-axis perpendicular to the scattering plane.
		The dynamics of ice is rich - not only is it an analogue of the tetrahedral semiconductors, much of the dynamics couples to the disorder of the hydrogen sub-lattice.
	www.isis.rl.ac.uk /isis99/highlights/ice11.htm (1004 words)

	W.F. Kuhs: The Structure of Ice Ih (via CobWeb/3.1 planetlab2.cs.unc.edu) (Site not responding. Last check: 2007-10-12)
		Ice was among the first compounds to be looked at with X-rays, and when neutron scattering became viable a powder spectrum of ice was among the first to be recorded.
		Over the years methods of measurement and interpretation have developed, and at regular intervals ice has been studied, leading to precise and detailed picture of the atomic arrangement in ice Ih.
		The crystallography of ice Ih The ordinary hexagonal ice,called Ice-Ih, is one of the most thoroughly disordered crystalline materials.
	kristall.uni-mki.gwdg.de.cob-web.org:8888 /Docs/Kuhs/hexa_ice.html (606 words)

	apostropher: How much do you know about ice?
		The crystal structure of the ice is fairly loose — the reason that Ice Ih is less dense than liquid water — and the bonds that the hydrogen atoms form between water molecules, called hydrogen bonds, are weaker than most atomic bonds.
		When my sister did a stint in Antartica, she reported that researchers there have developed a very stringent etiquette for what kind of ice can be put in what kind of drink.
		Ice Ih is not a crystal structure of the water molecule.
	www.apostropher.com /blog/archives/003024.html (976 words)

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