Epsom Salt + copper wire gone awry!

[Tori]

So, I'm a newb, and although I saw something similar to this when I searched, I wanted to find out something...

 

My mom wanted copper sulfate for painting. We discovered that my brother had a chem kit including epsom salt (MgSO4) and copper wire.

 

A 25 mL 1M solution of MgSO4, a 9V bolt battery and a little wire-and-connector thing that goes with the 9 V battery later...

I have a clear solution with a very light green, fluffy-looking precipitate settled at the bottom.

 

So, what I'm asking is, what is this? The red side of the wire completely disintegrated from the wire-and-connector thing and I have no idea what kind of metal it was. Googling light green precipitate didn't help out much.

I mean, I'm going to do the experiment again using the copper wire (which has now been cleaned of the plastic coating I had failed to realize it had) as electrodes, but I'm really curious about this one.

 

Any ideas?

[hermanntrude]

you're going about this all wrong. MgSO4 and Cu are quite happy the way they are, and electrolysis isn't magic. it can be quite complex. I'd guess that what you made was copper sulfate but you also probably generated a lot of hydrogen and oxygen and perhaps also changed the pH of the solution. Copper salts often change colour depending on what else is around.

 

copper sulfate is surprisingly difficult to make, but the easiest (although certainly not a safe method) involves the use of both nitric and sulfuric acids and copper. You will only be able to use this method if you have a fume hood, and a proper laboratory method.

 

there may be a viable electrochemical method but sticking some copper and "something with a sulfate ion in it" in a beaker and ramming it with as many volts as possible is going to be complicated

[Tori]

I actually think I got it to work regardless, and a friend and I think that the precipitate from my first attempt is Nickel (II) Hydroxide. I realize that it's not magic, but theoretically it should work, and I believe it did. Besides, I'd already seen on here in other posts that it had.

[UC]

I actually think I got it to work regardless, and a friend and I think that the precipitate from my first attempt is Nickel (II) Hydroxide. I realize that it's not magic, but theoretically it should work, and I believe it did. Besides, I'd already seen on here in other posts that it had.

 

Nickel!?!?

[crazybrain68]

Why do you think it is nickel? Nothing in your original post mentioned anything about nickel

[Theophrastus]

As Hermanntrude said, the copper and magnesium sulfate do not react, and if they do, due to the copper's 'excited' state, the magnesium will gladly displace the copper, and the solution shall return as it was. In terms of testing the identity of the precipitate, I'ld guess that it may be copper hydroxide, though the colour of hydroxide isn't exactly green. Is the colour consistent throughout, as if it isn't there could be a bit of carbonate, due to further oxidation. Hydrated copper chloride sounds more like your description, but copper chloride is soluble, and generally, ions don't magically appear from thin air.

It could also simply be due to impurities, so I recommend that any information you have, particularly if you've discovered your electrode to be copper plated (its happened to me before ) you ought to elaborate on your layout and let us know.

You should also do a flame test, with this green precipitate, to see if its a copper compound. If so, try adding hydrochloric acid, and if you get the characteristic colour of copper chloride, It's most likely hydroxide. (copper II oxide is black)

If you find that it isn't a copper compound, in which case, I can't really help. Though if you need help, I recommend mentioning a little more about the layout. Where did the idea of it being a nickel salt come from?!?

Edited May 11, 2009 by Theophrastus
grammatical correction

[Justonium]

Sounds like you made copper hydroxide. Remember, the weakest ion is the one that you are going to remove from the solution. In this case, magnesium is stronger than hydrogen, and sulfate is stronger than hydroxide, so the only function of the epsom salt will have been to carry a current through the water, but you were still separating water.

 

Edit: copper hydroxide is light blue, so this could not be what you made. I would guess you some how made copper carbonate (the green stuff you see on old copper roofs and on old pennies). Dunno how though. That is weird, almost as if you were using carbonated water.

Edited May 20, 2009 by Justonium
wrong information