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Originally Posted by wadeintothem
Spirits of ammonia mean nothing except for ruining some good ice. It is hogwash. Surely someone has some sort of evidence that this is helpful other than east coast blather and fairy tales. I know I've looked high and low for some reputable evidence. If someone has some evidence I'd love to be corrected on this.
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Not being a scientist, I'm going to take a stab at this....
The amount of heat needed to change a given amount of liquid to a gas without a change in temperature is its HEAT OF VAPORIZATION, sometimes referred to as latent (hidden) heat. The heat of vaporization for water is 540 calories per gram (9720 cal/mole) and the heat of vaporization for ammonia is 327 calories per gram (5559 cal/mole).
As we all know, it is the evaporation process that makes you feel cool as heat is required for evaporation. Since it takes less heat to make ammonia evaporate (327 c/g), more ammonia can evaporate faster thus creating a cooler sensation than just water alone (540 c/g). Using an ammonia/water solution lowers the heat of vaporization of water (I'll leave that to the scientists to tell you the exact numbers) thereby making this solution 'cooler' than just water alone.