Different Kinds of the Same Salt

Most recent answer: 10/22/2007

Q:
i would like to know if you guys/girls know anything about what poretrzal salt,table salt, and rock salt are made up of and how fast do they melt ice cubes
- donnie (age 14)
beaver,pa,usa
A:
Hi Donnie,

The salt used on pretzels is the same kind of salt in the salt shaker on the table, is the same kind of salt found in bags of rock salt. It’s all sodium chloride, NaCl.

Actually, some people are concerned about their sodium intake and substitute potassium chloride for sodium choride some of the time, but this is uncommon. I don’t like potassium chloride on my food. Some fancy table salt is "sea salt", which also contains mixtures of calcium chloride and other minerals found in the sea. Table salt (and pretzel salt) also usually contain a small amount of added iodide, a vital nutrient. None of these differences should have any effect on how well it melts water.

What may have an effect is how finely ground up the salt is. Rock salt comes in big chunks and only will help melt the ice it comes in contact with or ice that gets water on it containing salt dissolved from the big crystals. Finely ground-up salt presents more surface area and more rapid updake of the salt by the melting water. If the salt is first dissolved in water, it won’t make any difference which one is used.

Tom

(published on 10/22/2007)