[therion]

I've run into a dilemma where it comes to evenly distributing two water soluble compounds so that they are as evenly distributed as possible.

Now compound A: I have about a gram (just an example amount)

Compound B: I have about 20 grams (again a sample amount)

My end goal is to somehow get these two soluble substances mixed as evenly as possible in their dry crystalline state.

At first I figured just add everything to the water, dissolve it all and recrystallize everything together. This however, won't create a completely evenly distributed mix.

The problem here is that the compound B will begin to form crystals first during the evaporation process, as there is much more of it. Thus forming vast pockets of dry crystals that do not contain substance A. There will be uneven pockets of compound A all throughout compound B once everything has crystallized. So this is not evenly mixed.

Is there another way to get something with a much smaller amount (substance A), to be evenly distributed in dry form throughout the larger compound (substance B)?

The (A) compound must remain the same. The whole goal of the project is to distribute it evenly in something. As far as B goes, I can replace it. What if I found something to replace B with that is say 20x more soluble in water than A. Then add A at a ratio of 20:1. will this still cause A and B to crystallize out of the solution evenly and at the exact same time?
Are there any other ways to accomplish a completely even mixture between two compounds, in the same sort of proportions listed above?

I'd really appreciate any advice. If this is the wrong forum for this, please let me know and I'll go to the right place.
I've worked with chemistry all throughout my younger life, I'm trying to get back into it. This is for a personal project. Thanks for your time.

[Borek]

Ball mill comes to mind. Just fill it with dry compounds.

I am moving it to citizen chemist.

[Intanjir]

Maybe try this:
Start with a solution saturated at room temperature with A and B, with everything still dissolved.
Then prepare solutions saturated at elevated temperature, one of A and one of B.
Now mix these in some ratio you tune to give the desired result and add dropwise to the starting solution(perhaps over a very long time period).

Each drop supersaturates the solution once everything cools to room temperature and the compounds should want to precipitate until the solution is saturated again. With a little algebra we could figure out what input ratio of the drops would theoretically yield what output ratio of the precipitate.

If one of the substances grows crystals at a much faster rate than the other then you can't just add all the drops at once. You need to allow time in between drops to allow the other substance to also precipitate.

Once you have big enough particles just run things through filter paper, wash, and collect the solid particles. Discard the saturated solution, or save it for later if you want to do it again.

I would think this could yield something much more homogeneous than evaporation, but will it ever be totally homogeneous?
Probably not. Unless the two substances have highly compatible crystal lattices they will preferentially precipitate wherever they encounter their own lattice. So at best you will have solid particles in solution each consisting of micro-sized domains of each separate crystal. In the worst case they would precipitate as completely separate particles. The choice of substances and degree of supersaturation of the drops should effect how homogeneous things are.

How on earth are you going to verify whether you have something homogeneous?

[therion]

Thanks a lot for the time and input thus far. I was contemplating a way to get the crystals to precipitate, but as you mentioned at the end, there's no way for me to be sure.. or any way I can think of to verify the results really.
In the end I suppose I will be faced with that problem no matter which method I try to obtain this mixture.

[Intanjir]

Thinking about it I suppose that if the two substances have different enough densities you could potentially do it by testing the distribution of densities of the particles you precipitate.

So if the two substances precipitated as completely separate particles then if you chose a non-solvent liquid with the right density, one set of particles will float and the other set will sink(A centrifuge would be helpful).
More realistically even in the case of separate primary particles, you will still get composite particles which are just clumps of particles of different kinds sticking to one another. This will definitely happen if you make the mistake of drying them before testing like this. Anyways so you might not see dramatic separation unless you break the clumps up first with sufficiently high shear mixing. Or maybe just ball milling would work.
 

Then again if you don't dry and the non-solvent is immiscible with water then you might see different densities just because different particles adsorbed different amounts of water....

[Intanjir]

Two other methods:
Flash freezing the aqueous solution, and then freeze-drying. Possibly by dripping into liquid nitrogen.

Choosing substance B such that it when molten it dissolves substance A and then resolidifying. If A and B form a solid solution then it will be perfectly homogeneous. If not then you may want to chose B to be something that readily forms a glass and solidifying them very rapidly.