All atoms have intermolecular forces that keep them together as solids or liquids. Adding energy will overcome these forces and cause them to change phase from solid->liquid->gas (with a few that jump straight from solid to gas).
Energy has to be added to cause this phase change. Going in the opposite direction requires withdrawing energy.
The types of forces or bonds (not chemical bonds) absorb energy when broken, give up energy when formed. It implies that the solids are in a lower energy state than liquids, and liquids lower than gases.
This said, when water turns in ice, heat energy is being withdrawn, and the molecules are getting into a more stable and fixed configuration with respect to each other. Because of the polar nature of water, it forms hydrogen bonds between molecules. These type of bonding means when water turns into ice, it positions the molecules into very specific configurations, to maintain the lowest energy state it can get to. Hence the formation of ice crystals.
2006-11-13 02:30:21
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answer #1
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answered by Radagast97 6
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Start with a closed thermodynamic system of an ice cube in a glass. As you add energy in the form of heat, the motion of the water molecules increases, but stays in the form of vibration, with the molecules staying in place within the solid structure. That's 20 people holding hands in a circle, swaying or walking faster back and forth, but still holding hands.
It takes energy to break the 'bonds' of a water molecule with its solid structure. But if you add enough energy, these bonds break and the molecule can move more freely. When no one is holding hands, the whole system is liquid.
In terms of thermodynamic calculations, the whole system will be in whatever state (solid, liquid, gas, or a mixture) minimizes the Gibbs Energy of the system.
With carbon forming the regular crystalline structure of diamond, I think it really is a chemical bond, where the bonding between adjacent carbon atoms is the same bond as between the carbon atom and each oxygen atom in carbon dioxide.
In this covalent bond, electrons tend to congregate between adjacent nucleii because they are electrostatically attracted to both. This tends to draw the nucleii together. But electrostatic repulsion between the nucleii pushes them apart, and the whole structure has a lower energy when some outer electrons are orbiting multiple nucleii than when the electrons stay within a single atom.
I have not yet figured out what's happening between water molecules in a liquid or solid. Ice is crystalline when it forms on glass or in air as snow, but it's usually amorphous. Water in liquid or solid form is practically incompressible. But I don't know what determines that density.
2006-11-13 04:22:30
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answer #2
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answered by Frank N 7
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Ice turns into water because Ice is the solid state, and water is the liquid state. Depending on the Melting and Freezing points the molecules either expand or contract. It also turns into a gas state when it vaporizes into the air, which is what you see with steam. Condensation is another form of vaporization in it's gaseous state.
2006-11-13 02:27:10
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answer #3
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answered by kelly A 2
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Not only is heat required to raise the temperature of the solid to the melting point, but the melting itself requires heat; see also latent heat and heat of fusion.
From a thermodynamics point of view, at the melting point the change in Gibbs free energy (ΔG) of the Material is zero, because the enthalpy (H) and the entropy (S) of the material are increasing (ΔH,ΔS > 0). Melting phenomenon happens when the Gibbs free energy of the liquid becomes lower than the solid for that material.
Latent heat describes the amount of energy in the form of heat that is required for a material to undergo a change of phase (also known as "change of state"). This concept was introduced around 1750 by Joseph Black. Two latent heats are typically described. One is the latent heat of fusion (melting), and the other is the latent heat of vaporization (evaporation).
They are so named as to describe the direction of heat flow from one phase to the next:
solid → liquid → gas.
The energy change is endothermic when going from solid to liquid to gas, but exothermic when going in the opposite direction.
For example, in the atmosphere when a molecule of water evaporates from the surface of any body of water, heat is transported by the water molecule into a lower temperature air parcel that contains more water vapor than its surroundings. Because energy is needed to turn water into water vapor, water vapor is a way for a body to release energy. If the water vapor is returned to a liquid or solid phase (by condensation or deposition), the stored energy is released as sensible heat onto the surface where condensation (or sublimation) has occurred.
2006-11-13 02:26:53
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answer #4
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answered by Anonymous
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water turns into ice
2014-01-26 12:46:38
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answer #5
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answered by Dusica 1
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ice is basically a water...water can change it's phase to solid or gas...by cooling the water, it turns into ice..by reversal of the process, when ice is heated, it turns into liquid...
2006-11-13 02:38:38
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answer #6
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answered by Treat 2
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It melts. Caused by temperature higher than 32°F (0° C).
2006-11-13 02:22:53
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answer #7
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answered by Anonymous
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if it has jity
2014-07-06 20:01:29
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answer #8
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answered by SUSHILAH 1
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