freezing point of a SW pool

[kjcole]

Does anyone know how 3000 ppm salt affects the freezing point of water? I'm guessing it will a little, but not enough to matter to a typical Iowa winter.

Kelly

 

[chem geek]

The amount of salt in an SWG pool has a negligible effect on the freezing point of water.

The formula is that the freezing point depression for water, in Celsius, is 1.86 times the molality of dissolved substance. 3000 ppm salt in water is around 0.05 moles/liter which is essentially the same as molality (moles/kg) since the density doesn't change much. You double this concentration since sodium and chloride ions are separate so around 0.1 * 1.86 = 0.186C = 0.3F so not even one degree improvement.

Richard

 

[kjcole]

Thanks. That's less than I figured, and I was figuring small!