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Calcium Chloride Solution

rjreusch

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Apr 18, 2015
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Hello, I decided to make up a CaCl2 solution rather than use the solid. I did this because of the hydrophilic nature of CaCl2. It will rapidly take up water and you don't get an accurate weight. So I put 79 g of CaCl2 in about 490 ml of distilled water (water was room temp so about 490 g). The solution gets hot and I cooled it back to room temp and measured the specific gravity as 1.121 which should correspond to a 13.1 weight % solution. This is in pretty good agreement with 79 g in 569 g of solution. When I stored (at room temp) this solution I got a white precipitate that will not go back in solution. Its like I'm above the solubility limit which should be 74.5g in 100ml of water!!!
Am I making a serious calculation error? Has anyone seen this precipitation? Could it be impurities in the solid CaCl2?
Thanks, Bob
 
Ok, kind of embarrassed. I think by technique was correct and specific gravity of solution (need accurate hydrometer) confirmed an actual weight percent not the approximate I would have using the solid and not knowing how much water it may have picked up over time. And, the calcium chloride would not crystallize out of solution at 14% until very cold temperatures (I checked phase diagrams). So my theory is the mason jar I used had some film (hard water deposits) that somehow occurred when they were used for canning. These deposits probably came free during the mixing of the calcium chloride in water (exothermic and it gets very hot). So there is probably some calcium carbonate that I'm seeing which is much less soluble particularly in the calcium chloride solution. Sorry for the question and I recommend making up the solution if you like accuracy and in particular for high chloride water that you might use for something like an NEIPA. Bru'n water premium makes it very easy since you can plug in the SG of the solution and it gives you the weight %. You then select "liquid" for the form of calcium chloride and it gives you the required grams solution per gallon of water.
Bob
 
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