[wireframewolf]

Hey all. I'm trying to teach myself chemistry at home, and I've got O'Reilly's Illustrated Guide to Home Chemistry Experiments, published under their 'Make' line of books. Perhaps some of you are familiar with it

I was thinking about doing the experiment where one purifies crude Copper Sulfate via recrystallization, since I found a two pound canister of Root Kill in my garage which claims to be 90% Copper Sulfate.

Now I understand the concept of the purification: No room in the crystal lattice for extra stuff, so it gets 'pushed out' as the Copper Sulfate crystallizes. But my question is this... is there some experiment I can do at home, comparing the 'purified' copper sulfate vs the crude stuff and come out with some empirical evidence that the technique I used worked? The root kill and purified copper sulfate look to be basically the same, so I can't tell by looking.

My tools are rather limited, although I could perhaps invest in some equipment if it is useful and not too expensive. I have a scale that measures to .05 grams (up to 100 grams), a multimeter that measures to 1/1000th of a volt (I was thinking perhaps there would be a measurable difference in conductivity that I could test). Perhaps there is even some chemical test that would have noticeably different results between 90% copper sulfate and the purer stuff.

One thing I have is some copper sulfate I bought from United Nuclear, which I suspect is >99% purity, although I didn't see any specs on their site. Perhaps I could use this as a reference as well.

This is all just for the learning experience, and any advice or ideas you can throw at me would be much appreciated

[Borek]

The most obvious approach would to be analyse for impurities. But for that you would have to know what they are.