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which is suitable for producing KCLO3 by electrolysis, fertilizer grade KCL(0-0-60) or food grade KCL? Answered

fertilizer grade is 0% N, 0% P, 60%K and the rest is KCL while food grade KCL is about 49% KCL and the rest is NaCl


Jack A Lopez

7 years ago

The way they calculate those NPK numbers is kind of strange. 
I think it is the  mass fraction of each element (N, P, K, respectively), then multiplied by [ 1.0, 2.3, 1.2]. 

For pure potassium chloride, KCl, the mass fraction of potassium is

39.10 / (39.10+35.45) = 0.5245,  where 39.10 is the molecular weight of K, and 35.45 is the molecular weight of Cl.  Pure KCl contains no nitrogen, and no phosphorous.

So that's [0, 0, 0.5245] .* [ 1.0, 2.3, 1.2]  = [ 0, 0, 0.6294]

And that is my best guess as to how the fertilizer mongers come up with that number [0, 0, 60]

What I think that means is that fertilizer grade KCl is much closer to being pure KCl, than something you know to be only 49% KCl (by weight?)

Also I have seen KCl sold in 40 pound bags as water softener salt.  It usually comes in a different color bag, and is much more expensive than the usual kind, which is NaCl.

BTW, I think you've got the wrong formula there for potassium chlorate (KClO3),
if that is indeed what you are trying to make.

Jack A Lopezdavincicoder

Answer 7 years ago

BTW, I have not tried this, making KClO3 from electrolysis of aqueous KCl, or NaClO3 from electrolysis of aqueous NaCl.  So really I don't have much advice for you, besides what I've already written about finding KCl, and understanding what those N-P-K numbers on fertilizer bags mean.

Of course other people have written about the electrolysis setup for this. I seem to recall the temperature of the electrolyte might have been important, so I included that word in this Google search:
and that looks like it's returning some good links.

Also another thing I noticed, just reading about this, is that KClO3 is a lot less soluble in cold water than NaClO3, or KCl, or NaCl.  So if you've got a solution containing ClO3-, Cl-, Na+, and K+, then conveniently the KClO3 is going to precipitate out first.