Kirk Gordon wrote:
Cliff wrote:
On Mon, 26 Sep 2005 14:26:49 -0400, Kirk Gordon
wrote:


If the same salts are disolved in less water, the salt concentration
goes up, and freezing temps are reduced to even more extreme values -
WAY below 32F.


Actually, you may recall that below a certain temp they stop
salting the roads. No matter how much salt they might use it
would cause no melting.

Salt doesn't cause melting in the first place. What salt on the
roads actually does is PREVENT water from freezing, before it gets
frozen.

Calcium Chloride is exothermic upon dissolution. Actually,
many salts are, though some are endothermic.

When cars and trucks drive over pre-existing ice, they create
pressure, friction, and heat with their tires. Then the salt prevents
water melted that way from RE-freezing.


In locales where the folks who salt the roads actually know
what they are doing they put the salt down _beofor_ it
snows. That stops ice from forming and sticking to the
pavement in the first place.

If you sprinkle salt on top of ice it will make little pockmarks
around each of the crystals or flakes of salt.

--
FF