How can I prove the compound I made was the one I was aiming for?

Question

After taking two soluable compounds and making an insoluable compound, how can I prove I made what I wanted to?

Answer 1

Gotta do two things:

1. Isolate / separate
2. Identify

Isolate it... Filter it, recover the solid, dry it, weigh it.
Identify it... If its an inorganic salt, some sort of spectroscopy - AA, AE, ICP, something simlar. Organic salt? NMR, maybe IR will help.

There's also thermal analysis which will tell you what percent of what elements are there. But it's expensive.

Need more info as to what's available.

Answer 2

To prove that an unknown compound has the same chemical formula as what you expect it to be, you do the following steps;

1. Isolate and purify. In your particular case, it is easy because you produced an insoluble (in water, I assume) compound product. Just filter and wash so many times. Then dry the product. it is important that your product is essentially pure.

2. Qualitative Analysis
a) Determine a few physical constants about your expected product and compare with published values. It is tougher if you are synthesizing a totally new compound. Else, you can determine the physical data like color, solubility in other solvents, density, melting point. If you get a good degree of correspondence with published data, you are halfway there. Please note that simply because you have the same melting point value means you have 100% confirmation. There are so many substances that may have similar values. And melting point determinations are not that "accurate". However, it limits your possibilities.

b) Elemental Analysis - This means you have to determine that the elements in your product are actually the same elements you expect to have. If you expect Copper and Iodine only, then you should be able to detect those two elements only. If you detect some of your other starting materials, it is possible you have impurities still and you must go back to Step 1.
The elemental analysis can done in a number of wet (old methods) or instrumental methods like AA for inorganics and GC-MS for Organics.

3. Quantitative Analysis
Sometimes you may have the same types of elements but they may not be in the right ratio of combination. For example, you do not know if you have cupric iodide or cuprous iodide unless you do a Quantitative analysis. Again, depending on the product, there are a number of classical and instrumental methods to do this.

Proving something is really the real thing is very rigorous and demanding especially if you are synthesizing a totally new substance, compound or product.

Answer 3

You ask them. The "soluble" and "insoluble" compounds tell you. I don't know why people waste soo much money on GC, GCMS, AA, IR, Raman, NMR, etc when all they simply have to do is take some time to talk to these tiny little buggers to get the answer they seek. Jeez.

Answer 4

Well, one way you could do it would be to separate out the insoluble compound with vacuum filtration, and take it's melting point, comparing that number against the melting point of what you expected.