Quote Originally Posted by Photo Engineer View Post
Patrick, using the simple principle of solubility and the common ion effect, I have explained to you how you can either concentrate an impurity in the mother liquor or in the solid. It is that simple. To do what you are describing, you must know what you are doing. If I cannot explaine some simple facts of chemistry to you, then I'm sorry.

You have to know what you are about, before you undertake it.

And, I said that what I had given was hypothetical, but nonetheless, your procedure as outlined will concentrate all halide and phosphate impurities along with other soluable sodium salts in the concentrated Borax solution.

I'm sorry, but that is a chemical fact.

PE
And it is also a chemical fact that the solution I am keeping is not the solution you are talking about. I am using the sediment from it to make a second saturated solution which cannot, according to your own lecture, be as impure as the first because the first has dissolved and carried away 95% of the soluble impurities. You apparently do not know what I am doing. Read it again or forever hold your peace on this subject. I gave a numerical example illustrating exactly what tou are preaching. The first saturated solution carries with it the soluble impurities in the 200 grams of borax, while dissolving only about 40 grams of borax. The remaining 160 grams of sediment contain only about 5% of the original soluble impurities. The first saturated solution is discarded or used around the house. The 160 remaining grams of borax are sufficient to make at least 3 liters of saturated borax solution. Have I said anything wrong so far? I'm beginning to think you are the one who flunked out of chemical engineering. This method of using differential solubilities to purify is very old. If I had a solvent that would dissolve everything but borax, I could eventually get very pure borax without losing any, but it would not be in the sediment. It would be in the last saturated water solution I made.