Expert: James J. Kovalcin - 2/16/2007

Question
OK, One last question.  What (Chemical(s), substances or elements) can be applied to an object to make that object cold?  Such as metal?  Basically, what can be done to metal to make the surface cold?
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I see how pressure can affect the freezing.  However, if you pressurize water, will it freeze?  If not, is there any chemical reaction with water and another substance that will make the water freeze.  What I am trying to do is make water freeze within a coil to cool air flow. So, it is possible for water to freeze if mixed with another substance or substances?  Thanks
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I have a question about freezing water.  What is the quickest way to freeze water, I mean this by:  can you add another element or chemical to cause a quick freezing reaction? specifically in an enclosure, like copper tubing. any info you have, would be greatly appreciated. Thanks.
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Actually, the addition of ANY impurity will interfere with the freezing process. This is called a colligative property and is based on the idea that impurities in the water get in the way of the water molecules trying to arrange themselves into a crystalline structure! So, if you want water to freeze, the best thing to do is to make sure the water is pure. You can also increase the pressure. Water will freeze at a lower temperature if it is under high pressure.
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Yes, if you apply large pressure to water confined to a small space you CAN cause the water to freeze [form a solid] but this will NOT make the water cold! Many materials can form solids under high pressure, but high pressure in this case has nothing to do with being cold! For example, water will boil at room temperature is you lower the pressure below about 25 Torr. But the water will NOT be hot! The change from solid to liquid to gas is called a "change of phase" and while such changes are related to the temperature, it is possible to initiate such changes WITHOUT changing the temperature.
So I think that your goal cannot be reached in this way.

Answer
The temperature of an object is directly related to the kinetic energy of the atoms within. To cool something off one has to remove kinetic energy from that object! The only way that can happen is for this kinetic energy to flow from the object to something or somewhere else. In principle you can combine chemicals together that chemically react in an endothermic reaction - meaning that heat flows into the chemicals as they react. This could [at least in principle] be used to cool the metal object. I do not really believe that this would be really practical. Sorry.