Does hot water freeze faster than cold water?Why?

Answer 1

because the oxygen has been removed and the monacules don't have to bounce off each other so it will freeze faster

Answer 2

The phenomenon that hot water may freeze faster than cold is often called the Mpemba effect. Because, no doubt, most readers are extremely skeptical at this point, we should begin by stating precisely what we mean by the Mpemba effect. We start with two containers of water, which are identical in shape, and which hold identical amounts of water. The only difference between the two is that the water in one is at a higher (uniform) temperature than the water in the other. Now we cool both containers, using the exact same cooling process for each container. Under some conditions the initially warmer water will freeze first. If this occurs, we have seen the Mpemba effect. Of course, the initially warmer water will not freeze before the initially cooler water for all initial conditions. If the hot water starts at 99.9° C, and the cold water at 0.01° C, then clearly under those circumstances, the initially cooler water will freeze first. However, under some conditions the initially warmer water will freeze first -- if that happens, you have seen the Mpemba effect. But you will not see the Mpemba effect for just any initial temperatures, container shapes, or cooling conditions.

It is still not known exactly why this happens. A number of possible explanations for the effect have been proposed, but so far the experiments do not show clearly which, if any, of the proposed mechanisms is the most important one. While you will often hear confident claims that X is the cause of the Mpemba effect, such claims are usually based on guesswork, or on looking at the evidence in only a few papers and ignoring the rest. Of course, there is nothing wrong with informed theoretical guesswork or being selective in which experimental results you trust -- the problem is that different people make different claims as to what X is.

Answer 3

It can do but not under all conditions, it can be explained by standard physical theory which may included any of teh following effects:

* Different definition of freezing (Is it the physical definition of the point at which water forms a visible surface layer of ice, or the point at which the entire volume of water becomes a solid block of ice?)
* Evaporation, reducing the volume to be frozen
* Convection, accelerating heat transfers
* The insulating effects of frost
* The effect of boiling on dissolved gases
* Supercooling. It is hypothesized that cold water, when placed in a freezing environment, supercools more than hot water in the same environment, thus solidifying the hot water faster
The effect of solutes such as calcium and magnesium carbonate.

Answer 4

I have heard that boiling water freezes faster than cold water. The explanation was that boiling water causes steam when put into a freezer, making less water in the bowl, using less time to freeze. I have never tried this myself, either didn't care, or had better things to do. I'm sure the government has spent millions of dollars on research for this question.

Answer 5

OK, here is the real answer. Warm water freezes faster than cold water. The reason is that cold water freezes on the surface first thereby trapping the remaining heat in the unfrozen water. Warm water cools uniformly on the inside and on the surface, i.e. there is no ice layer to trap in the heat.

Answer 6

Of course hot water would not freeze faster. Water, like any substance, must reduce in temp until it, well reaches frozen levels. So, if you have something at 40 degrees and something at 85 degrees which would freeze faster considering freezing starts at 32 degrees?

Answer 7

Sometimes. It depends on a number of factors - quantity, actual difference in temperature, temperature at which water is left to freeze, etc...
The reason is that hot water evaporates faster. So by the time it freezes, there's actually less water to freeze.

Answer 8

no, it doesn't, and it is a common sense question. hot water takes longer to freeze because it is hot and takes longer to cool off. cooler water freezes faster because it is already cold and reaches freezing faster. there. you could have asked your science teacher instead. experiment at home and you will see. put both hot and cold ice cube trays in the freezer and watch to see which one freezes first.

Answer 9

hot water freezes faster, cause the ions or whatever there called are already more spread out.

Answer 10

Strangely, yes.
It has something to do with water molecules being already excited by heat, which is the same thing that happens when it gets cold, it just goes into crystal form when frozen. Or something like that, it never made any sense to me.