does hot water freeze quicker than cold?

Answer 1

Under normal circumstances no. There is an exception within a temperature range of about 85-95 C where some of energy required for the change of state is taken from the heat energy and allows the water to freeze a little faster. This can only be demonstrated over a large surface area.
For example when washing a car in freezing conditions, hot water will freeze on the surface faster than cold water but if you have two water buckets, the one with cold water will freeze first

Answer 2

Hot water does not actually freeze faster than cold water....it's a thermodynamic impossibility. But as you heat water, the dissolved oxygen in the water is released and you change the freezing point slightly. The phenomenon is called freezing point depression. If you add a very small amount of contaminant to a liquid, it's freezing point will actually be lower than the pure liquid. A common example of this is seen in homes where water pipes are run through the attic without insulation. Since the hot water lines are filled with liquid that has been run through the water heater, that water has been "degassed." That is the dissolved oxygen has been driven off. In an idle pipe, the water slowly cools to ambient temperature, or the same temperature as the cold water lines. Then when cold weather arrives, and the uninsulated line reaches 32 degrees F, the hot water line will freeze first.

Bottom line is that it has nothing to do with how hot the water is compared to cold, but how much dissolved contaminants are in the water.

You can do a home demonstration by adding a teaspoon of salt to one cup of water and none to a second cup. Put them both in the freezer and see which one freezes first.

Answer 3

I have heard that if you try make ice form cold water and hot water separately the hot water will freeze faster but only because the hot water makes the freezer work harder. To accurately do the experiment, you have to put a tray full of cold water and one full of hot water in the freezer at the same time. I guarantee the cold water will freeze faster every time.

The links that other people gave do not show that hot water freezes faster than cold water. If you read them carefully, they point out that in certain circumstances hot water can freeze faster than hot water that is not quite as hot.

Answer 4

I've not tried the experiment myself, but have heard that hot water will freeze faster than cold water. You can't use hot water out of the tap, however. It's not hot enough.

I have done this part. If you heat water on the stove, you will notice very small bubbles forming at the bottom of the pan. They are not steam bubbles. If you use a spoon or something to knock these bubbles loose, they float up to the top of the water. If they were steam bubbles, they would cool and disappear before they reached the surface. These bubbles are dissolved gases that are being driven out of saturation. If you continue to heat the water, you will see more bubbles forming, and when they come off the bottom, they disappear before they reach the top. These are the first steam bubbles. As the water continues to heat, the steam bubbles reach the top of the water and it boils.

I was told the dissolved gases slows the formation of the ice crystals. If you look at ice cubes, you will notice small bubbles frozen into them. What I haven't done is take equal amounts of fresh, cold tap water and hot water with the gases driven out and put them in the freezer to see if there is a difference in freezing rates. If you try it, please let me know.

Answer 5

Yes hot water freezes quicker than cold water. If you put water under pressure it even freezes faster.

Answer 6

It depends on how hot the water starts out. The hotter it is, the quicker it should freeze. See second part of article below.

Answer 7

This is a popular misconception. When an object is hot, it has more energy. Frozen water has the least amount of energy (water that is deprived of as much energy as possible). Hot water has more energy to lose.


Oh, and with regards to the pressure thing, it will work..higher pressure causes the water to release heat (hence, reducing the amount of energy in the water).

Answer 8

If I remember my High School science correctly, Yes, it does.

Answer 9

Yes it does. Click on the following link and it will give you the explanation. http://math.ucr.edu/home/baez/physics/General/hot_water.html

Answer 10

Yes. It has more oxygen in it.