salt water or sugar water, which freeze the fastest and why?
959702
If you make them the same concentration (say 1 molar of each) the salt water will have a lower freezing point, and so will need to be colder before it freezes.  Freezing point is affected by the concentration of particles dissolved in the solution.  Since salt forms two ions and sugar forms only single molecules, you have more particles in a salt water solution than you do in a sugar water solution.
330025
it's frostbite. the water melting off the ice cube is because salt lowers the freezing point and so the water on your skin is very cold <32 so it freezes the skin. kinda like making ice cream except more painfull
786403
a) a lower freezing point than pure water
199763
What context are you describing (or is that what you are asking)?\n\nHot water will freeze slower than cold water.  In order to freeze the water temperature must be dropped to freezing temperature, and the farther away you are from freezing, the longer it will take to 'bleed' the temperature away by any known method.\n\nI am not aware of any condition where hot water will freeze faster than cold water, assuming the water in both situations is exactly the same (i.e., not water made of different material, or with another chemical in aqueous solution), so if someone can give this example, I would be very curious to see it.\n\nPerhaps there is a situation where you can heat a liquid to convert it into gas, and then from gas directly to solid (frost formation is an example of this).  I am not sure, but this might be one approach to try getting water to go to a solid state faster when the water temperature is initially higher.  The key is you are bypassing the liquid state.\n\nAddendum:\nActually now that I think about it, I have an aswer.  If you have supercooled water, i.e. water that is below freezing, it could stay in that metastable state indefintely.  So here is a case where hot water would cool faster.  The hot water will cool down to freezing and will freeze, while the supercooled water may never turn solid.\n\nAddendum:\nWow, this link that someone below posted is interesting:\nhttp://math.ucr.edu/home/baez/physics/General/hot_water.html\n\nI was going to say that it is impossible, since water at a higher temperature would have to pass through all lower temperatures, but this article pretty much explains it (in that, well, we just don't know).  It has been observed, but there is no explanation that can be agreed upon.\n\nTo be completely pedantic, I note that most of the explanations point to what I would consider to be "experimenter's errors" in the set up of the experiments (if more dissolved gas is in hotter water, than the two water mixtures are certainly not the same, so this is an invalid experiment... if there is a 'hot top', then the experimenter did not start with a homogenious mixture, and that has to be mentioned in the experiment... if the surrounding environment is not the same, then the ambient conditions are changing which not an assumption in a traditional experiment, but rather a source of error... if evaporation is allowed than some quantifiable mass of the water is not turning solid, so this again is invalid).  The only explantation that doesn't result from a poorly set up experiment is supercooling.
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.
136745
Good question!  You obviously know that glacial ice is not the same as frozen water in an ice cube tray in your freezer!  (glacial ice is compressed snow)  My initial response was that icebergs float, so yeah, it would float.  Then I thought that seawater is salty, which can cause more dense things to float and doesnt nescessarily provide a good proxy for a cup of drinking water.  Thennnnnn (you like following my train of thought here?) I remembered that icebergs calve into fresh water lakes, too and float.  So my long-winded non-quantitative answer is yes.  :)\n\nI have no idea if there is a difference in rate of melting, but my best guess is that it might take SLIGHTLY longer to melt.
650938
Saltwater WILL freeze. The temperature at which it freezes, however, depends on the amount of salt you add to the water. The more salt you add to the water, the lower the freezing point for the solution. You will reach a point when you have added so much salt that the freezing temperature will not decrease anymore.
378321
Sugar does because its bonds are non-ionic. Salt has ionic bonds and they are harder to break in order for it to dissolve.\n\nHOWEVER, there are many factors to be considered. fine salt may dissolve faster than a large piece of rock candy. The surface area to weight ratio of the solid plays a huge role in the rate.\n\nOh. And flour isn't very soluble in water.
118663
I'll take a stab at this one.  \n\nIf you're comparing the two, water will disolve more NaCl than it will Sodium bicarbonate because it dissociates a lot faster and effienciently (due to its electronegativitiy and other factors).  \n\nOn that same note, if you are asking directly if both dissolve faster in cold or hot water, hot water is always your best bet with solids dissolving in water.  On another note, if you want to disolve a gas in water lower temperatures are pretty much the only way to accomplish this (but thats a different topic).  \n\nSo in short, both will disolve better in hot water!\n\nCheck out the source below it is very helpful.  Oh and by the way, Sodium bicarbonate does dissolve in water.
629453
warm water dissolves ice faster than warm air because it can transfer and absorb heat faster than warm air of the same temperature
660432
Cold water is the best in this situation. Ice is too cold and can damage the surrounding area.
53261
salt's chemical composition breaks down bonds at an intermolecular level and lowers the freezing point of water...which is normally 32 degrees Fahrenheit. When the freezing point goes down...it melts
451585
water\n\n[edit] 6 seconds too slow!
292815
The answer is no and sort of.\n\nWater at 38 degrees (i.e. from the refrigerator) will freeze significantly faster (10 to 15 minutes faster) than hot water from the tap (125 degrees).  This is the range of temps most people are going to be dealing with.\n\nHowever, water at 190 degrees will freeze faster than water at 140 degrees.  The main reason is that more of the hotter water will evaporate before reaching freezing temps, so the ice cubes are significantly smaller - about 7/8ths the size of the cooler water.  Putting plastic wrap over the heated water reduced the time differential significantly.  \n\nI think the moral of this story is that you can get nearly any result you want by manipulating the conditions correctly.\n\nAlso, I feel the need to correct the second answer above.  Cooling is the process of slowing down molecular movement, not speeding it up.
27311
The normal freezing temperature for pure water is 0c.  However, as the additives are mixed in the pure water (in this case sugar), there will be a depression in freezing point (means lower than zero).  Ultimately it dependends on the sugar concentration in the water.  For an example, you can add few crystal in water and it will still freeze around 0c (slightly below unless you have accurate thermometer) vs sugary syrup that will require much lower temp.\n\nYou can llok up more of these in any Physical Chemistry book (mine is by author ATKINS) under "Depression in Freezing Point, Elevation in Boiling Point).
782227
Density is a measure of mass per volume. Same amount of water; sugar water is denser. Weigh; salt is NaCl, sugar is a more complex and heavier molecule. Formula for glucose. C6 H12 O6. Denser.\n\nNo. sugar water is denser than salt water. Period.
469919
Sounds like a trick question. In the north we know that putting salt on ice makes it melt. In the arctic regions only the salty sea water is still water. The ice and snow are actually fresh water. Salt lowers the temperature that water freezes at. However, if you can freeze dry the salt it will separate from the water. This is the method that's used to filter Ice Beer. So technically you could if done right but just freezing it is a difficult process because you'll need something very very cold as a coolant. This would be a good series of experiments if you can get someone that can handle dry ice (frozen C02).