Why is ice melting down, when you put salt on it?
469334
Because salt consists of sodium and chloride ions, and as You know, ions have charge, so You know there will be an interaction(attraction) between water molecules and the ions. You might also know that in ice, water molecules are in a definite distance from each other, they are in a crystal structure. Well, because of the interaction, that structure "opens up", and the water molecules get closer to each other, so the structure move from solid to liquid, as the interaction between them becomes weaker.\nI hope i was understandable. \nSalt lowers the boiling point and increases the freezing point of water. You can see it Yourself by putting salt into water, it'll boil sooner than without it.
379604
Rock salt and table salt ar two different ionic compounds.  Roack salt, calcium chloride, contains 3 ions: one calcium and 2 chloride ions.  Table salt has only 2 ions: one sodium and one chloride.\nSo who cares?  Well, the more ions (rock salt!) that are added to the ice (to make ice cream), the lower the freezing point of the ice will be.  Rock salt (3 ions) make the ice colder than the table salt (2 ions).  This is the only way the fatty moleculse of the cream can freeze into ice cream.  With table salt the ice just isn't cold enough.  The size of the salt crystals is not relevant.
562622
Let a chemistry student explain it.  \nThis here is something called a colligative property. A colligative property is a property that is affected by how many particles are involved.  \n\nNow, it just so happens that freezing point lowering is a colligative property.  That means that if you have stuff floating around in water, it needs to be colder in order for that water to freeze.  We put salt on icy sidewalks because when salt particles are in the water, the temperature has to be a lot lower in order for the ice to stay frozen.  That means that the ice is a lot less likely to stay frozen, so it melts.  \nI hope I helped!
66544
Salt will lower the freezing point of water. That is why the use in on the roads in winter.
60893
Sodium Chloride (NaCl), or salt, lowers the freezing point of water.  Putting salt on ice turns it back into water UNTIL the temps drop below the point where the salt water will freeze again which is between -9°C (15°F) and -21°C (-6°F) depending on the amount of salt suspened in the water.
23033
If you were able to get the salt solution cold enough, it would freeze. However, if you put two ice trays side by side, one filled with water, the other filled with salt water, and chilled them to the point where both froze, the would both be the same temperature. However, once the cold was taken away, the salt solution would melt at a much lower temperature than the water only cubes.\n\nWhat salt does when added to water is decrease the temperature at which water will freeze -- as well as melt. How much the freezing/melting point is lowered depends on how much salt is added. The higher the concentration, the lower the freezing/melting point.
199280
Salt causes the freezing point of water (and any other solvent for that matter) to be lowered. Thus, a salt solution freezes at a lower temperature than pure water. This phenomenon is called "freezing point depression." The extent to which the temperature is lowered is a function of the molality (moles of solute per kilogram of solution). That means that the more salt you add, the lower will be the freezing point.
436735
Ice and water are at equilibrium at 32 F (0 C).  A mixture of water and ice cannot be cooled below this temperature.   Salt depresses the freezing point (which is why it is added to icy or snowy roads in winter), allowing lower temperatures to be achieved.  This makes the viscosity build of the ice cream (caused by churning of the mixture) to occur in a shorter period of time, and keeps the ice crystals that form in the ice cream smaller - resulting in a smoother texture.
587656
So anti-freeze and salt causes a freezing point depression in the water which means as you add solvent such as salt the freezing point is lowered (hence when you add salt to your windshield the ice melts).  There is a simple mathematic equation that will relate the change of Temp freezing to the amout of solvent added.  (ΔTf = Kfcm).  Kf is the freezing point constant of the solvent and cm is the molal concentration of the solvent. So as you can see from the equation the ΔTf will be greater as you increase cm so the effects of adding a solvent will depend on how much solvent you add.  \n\nSo a simple experiment would be to add increasing amounts of salt and antifreeze to constant volumes of water and determine the freezing temperatures of each one.  You should also want to calculate the molal concentration of each one and try to determine before hand what the freezing points should be (hypothesis).
570058
the outside of the cubes melt the fastest while the inside are still froze.  What happens is the inside refreezes the melting outside therefor sticking together.  This will even happen while in ther freezer (if it is a self-defrosting kind)
162986
We typed "how does salt melt ice" into the Yahoo! Search box and were soon traveling the well-worn path to How Stuff Works. \nThere we learned that the answer has to do with melting points. Most people know that water freezes at a temperature of 32°Fahrenheit (0°Celsius). Salt dissolves fairly rapidly in ice, lowering its freezing point in an effect known as freezing point depression, and melting it in the process. \n\nBut what's going on at the molecular level? Basically, salt molecules are bonding with water molecules, making it more difficult for ice to form. The result is a solution with a lower freezing temperature. For example, a 10% salt solution freezes at 20°F (-6°C), while a 20% salt solution freezes at 2°F (-16°C). \n\nYou've also probably noticed the effect of salt water on freezing points if you've tried to make ice cream or if you've wondered why the ocean doesn't freeze at the same time as bodies of fresh water, such as rivers, lakes, and ponds.
674689
It's because of the lower pressure with the higher altitude.  Remember the phase diagram denotes the phase of a particular compound in terms of the pressure and temperature.  If you're sufficiently talented with respect to the maths, refer to a physical chemistry text and research upon chemical equilibrium and dG/dn.\n\nhttp://www.freewebs.com/chemistryhomework\n\nEDIT:  \n\nYou said:\n------------\nThe phase diagram doesnot explain this.\nYou forgot that it takes higher pressure to shift the freezing point higher in the phase diagram, not lower pressure like up in the mountain.\n--------------\n\nIncreasing the pressure makes it easier to melt ice, e.g. the pressure exerted by ice skates result melted ice at the surface, this is a common excerpt in introductory chemistry texts.  Again, also consider dG/dP and chemical equilibrium.
181797
Ice is water but in a solid form.  Water consists of H2O.  The bond between the H-O is a special one because of the difference of electronegativity is great enough but not enough to affect other water molecules and form a weak intermolecular H-O lattice, but not enough to form ionic bonds out of these.  So, this H-O lattice causes water to have properties such as this where at around 0 degrees Centigrade, it intermolecular forces and the lack of vibrational forces for the molecules cause them to form a solidified network latice of water molecules (ICE).  When rock salt is introduced, this lattice network is broken because salt (ionic compound) dissociates upon the impact of water.  Water is highly polar and the salt has a positive and negative charged ions associated to them.  These ions disrupt the network of hydrogen bonding that has faithfully held the water molecules together, thus changing the exterior requirments to solidify them.  Either pressure has to increase or temperature has to decrease in order to have intermolecular forces that are great enough to cause rigidity.  And there goes your reason why salt melts ice and the need for salt to melt ice from time to time.
194492
Salt raises the boiling point of the water. So if you add salt to the water, water boils at a higher temperature than 100C and cooks the pasta faster. It is the same procedure for the roads. Salt lowers freezing point of the water, so ice freezes at a temperature lower than 0C. If it is -5C outside the water doesn't freeze so the roads don't become slippery because of ice. Also this principle is used in the cars, i.e. antifreeze liquid.
259573
Ice water? If you have ice and water together they keep each other at the same temp. 0 degrees C. If you add salt this will make the ice melt at a lower temp. which will cause the water to be lower temp. also, giving you a below 0 C reading.
883409
I will assume that "salt" is referring to sodium chloride, NaCl.  The solubility of NaCl increases with increasing temperature and decreases with decreasing temperature.\n\nSince you are starting with a saturated solution (meaning that it contains the MAXIMUM amount of NaCl at that temperature) and you are cooling the solution to 20oC from 60oC, the cooler solution will not be able to keep the NaCl dissolved and you will observe small crystals of NaCl precipitating from the solution.
172797
there is ice when it is cold, this is known as being frozen