KOLM

Oh really?? So now I know you are an expert. No,I dont need to "take another guess". Rochelle has a 66% solubility (66g/100mls) @ 25 deg C, and to me that is very very soluble. (Low solubility is say, boric acid at about 5g/100mls in contrast). I am also a Chemistry expert in my field but have not had a need to boast about it. John, do you realize that "highly soluble" is a relative and subjective term? And your comment on how NaOH in water is considered violent is way off. No such thing. It gets hot, but in the industrial chem field that is not violent. Only sulfuric in H2O is considered violent. Come off your high horse, there is no calling for you to be offended from back/forth forum discussions about what is considered "highly soluble". Stick with your field.

You probably meant to type Potassium sodium tartrate. It is quite soluble. Now, on the 85% KOH, I am using conc KOH and conc NaOH. KOH conc is 11.7N and NaOH is 19N, both +/-. Already in solution form. But anyway, good tips just the same. I will proceed to mix a small sample, maybe just 100mls, and see how it goes. I trust yous agree with my stoichiometry calculations, in theory anyway. Will report back!! Thanks for the support.

Heres what I got: 1st, the max solubility of rochelle salt is about 2.5M. So, that means 2.5Moles of tartaric, or 375g (FW of tartaric is 150.1). Next, add 2.5 moles of KOH (FW = 56.1), or 140.3g. Lastly, 100g NaOH, (FW -= 40.00). Do this in enough DI water so as not to have violent splatter. Then qs to 1L, and cool, qs again. Sounds about right, Chemists? Thanks.

Thanks, members. So helpful. I will get back to yous for more detailed numbers..........

Hi, I have some tartaric acid crystal. Can anyone help me determine if my calculations are correct for making the rochelle salt? I figured for every mole in weight of the tartaric, I add each a mole of sodium hydroxide and potassium hydroxide, and stir in DI water. Maybe check for pH. Does that make sense? Thanks for your advice and expertise.

Thans again, Chen. That helps.

Meaning, to clarify, once damp, it is not anymore CrO3, but a different compound H2Cr2O7 (?).

Wow, Chen, I didnt know. So, even if I were to dry it out some, it would not revert back to CrO3?

Thanks, Chen. I need to dry it to avoid customers complaining about damp chromic acid. I guess I have nothing to loose from trying it, weigh up a small sample, the after a week reweigh. Might start with calcium (I dont have phos pentoxide handy, although a great choice.

Hi, Have some chromic acid and it is very damp as it is very hygroscopic. Does anyone know of a way to dry it out? Maybe over conc sulfuric acid or anhydrous calcium chloride? Could not find anything on the internet. Thanks.