[HistoricalEchidna]

Hi, I've been having trouble finding an explanation anywhere, so I thought this might be a good place to ask. I'll just summarise my experiment, and then I'll point out the parts I don't understand.

I was trying to find the percentage of copper within brass by first dissolving it in nitric acid and then using electrolysis to remove and weigh the copper. I had my copper nitrate solution and was using graphite electrodes connected to a 2 volt power pack, but the electrodes began to disintegrate when I turned on the pack. My chemistry teacher recommended changing the solution to copper sulfate, but I didn't really understand his explanation of why. Is there any reason why copper sulfate would be better for this electrolysis over copper nitrate?

However, the graphite electrodes disintegrated in the copper sulfate solution too. We expected one to just produce oxygen and the other to get coated in copper, but instead, the anode began to flake off and turn the solution black with graphite particles.
Does anyone have any idea why this might have happened? Is there some way I could have avoided this, like lowering the voltage or something?
Thanks!

[chenbeier]

Reason poor material of the electrodes. Better is to us as Kathode a copper tin and for anode insolouble material like titanium or noble element like silver or gold.