Does hot water really freeze faster than cold? If so, why?

Answer 1

On first inspection, you would say no, after all you first have ro remove enough heat to cool the water to the tempeture of the cold water, then the rate would be equal, so you would have the time that it took to lower the temperture + the time to freeze it.

However, that is leaving out one factor: evaporation.

Hot water will evaporate faster than cold water, so, unless you are in a sealed containter it is possible that you may lose enough water through evaporation that you will actually freeze the hot water faster.

Of course, a lot of factors pay into this, the exposed surface area of the water, the humidity inside the freezer, and the amount of water to start.


DRAT: Jano beat me to the answer. . .

Answer 2

It all depends on what the ambient temperature is. Pure Water has a different solidification temperature than water with gasses dissolved in it. Warm water tends to have less air dissolved in it than cold water. The warm water needs to be cooled only to a temperature just below 32 degrees Fahrenheit to freeze through. The cold water must be cooled to a much lower temperature due to the ever higher ratios of air to liquid water as the cool water is frozen and concentrates the air in the remaining liquid.

Answer 3

This is true, in some specific, rigorously controlled circumstances, hotter water freezes faster than colder water. This is because the escape of heat of evaporation can cause the hotter water to lose its heat and crystalize immediately. It goes from being a liquid to solid rapidly. Take a cup of boiling water outside in Antarctica, throw it in the air, and it will hit the ground as ice. Take a second cup of 40 degree F water, do the same, and it will still be water when it hits the ground.

Answer 4

Sometimes. For that to happen you must have a recipient with a big surface, for the hot water to evaporate quicky. When it ceases to evaporate, there is less water in the hot water recipient than in the cold one, so probably it will freeze faster. But in general, cold water will win the race.

Answer 5

Yes, because, unique to H20, when water freezes the molecules actually expand away from one another. Since heat causes the molecules to already be further apart, freezing becomes easier and quicker with hot water than with cold.

Answer 6

yes it freezes quicker because it has more heat to transfer since the process of freezing is all a matter of transfering heat since tempurature variables always transfer from hot to cold it makes hot water freeze faster by expending the heat to try and make the other medium of heat the same temperature which in a freezer the medium is too large for a tray of icecubes to heat it freezes the cubes by equalizing the temperatures between the cubes and freezer

Answer 7

it actually freezes clearer than cold water, but not faster....hot water has more energy to "get rid of" before it can freeze, so could not freeze faster....

Answer 8

the vibrations of hot water take longer to slow from their state of excitement than cold temperature water. cold water molecules are closer to frozen than hot, and are easier to slow than high speed hot water.

EDIT!: after this answer, I researched it, and to my surprise I found that it does: http://math.ucr.edu/home/baez/physics/General/hot_water.html

Answer 9

Yes it does! i tried it and it really works, but i don't know the reason why!!!

Answer 10

yes, the molecules are closer together to begin with.