White Precipiate When Making AR?

[warrendya]

I attempted to mix my first bit of aqua regia today. I used one part (40 ml) of poor man's nitric (made from sulfuric acid & sodium nitrate) and 3 parts (120 ml) of muriatic acid.

Upon mixing, a white saltlike precipatate immediately formed and fell quickly to the bottom. There was quite a bit of it, out of the 160 ml total in the beaker, the precipitate came up to about the 20 ml line.

I decanted the AR off of the precipitate and it seems no worse for the wear, it's bubbling away vigorously with some flatpack flour right now.

I've never heard of such a reaction before when making AR, so I figure it must be an artifact from using poor man's nitric. Anybody ever seen this before or know what it is?

That poor man's nitric was made with H2SO4 & NaNO3 in it; I figured when I made it and took it to -15C I removed the resultant sodium sulfate. But if there was any sodium still in solution, could it have simply formed NaCl when I added the HCl?

Dan

 

[Anonymous]

I think that most people when making AR with one of the so called poor mans recipes, just mix the nitrate with hcl, no need for sulfuric, at least that is what I do.

Jim

 

[eagle2]

Merck`s handbook states that the solubility of Sodium sulfate is decreased in water by NaCl.

Poor man`s nitric will always have some Sulfate left, no matter how cold you get the result. Calcium Nitrate is probably the best nitrate to use to get the least contaminated Nitric Acid.

But that`s an interesting way to get more Sodium Sulfate out of solution

Al