quote:
Originally posted by Muffy The Wanker Sprayer:
okay call me silly, but as I was a salad bar queen for a cupple of years at a restraunt this is what I know... when we set up the salad bar, we put in ICE, and then salted it to keep it frozen harder for longer... Don't ask me why this works, I just know it does, having forgotten to salt the ice on one occasion... so how is that salt can de-ice and keep ice icey???
A good question. Here's the deal:
Ice forms when water reaches 0°C. Salt lowers this temperature. So when you put salt on ice, it is more likely to melt, since the salt dissolves into any remnant liquid H20 in the ice and lowers the freezing point. At a certain point, around -9°C or so, salt does not have much effect as it becomes difficult for it to penetrate the lattice of ice to find residual liquid to begin the dissolving rxn.
To keep your salad bar cold, you add salt to ice because you want the temp around the salad items to be as cold as possible for as long as possible, so you lower the freezing point below 0°C. It doesn't keep the ice frozen longer, but it drops the temperature of the briny salt water that forms. How's that?