I'm essentially conducting an experiment to see whether using different copper-based compounds when electroplating copper onto an iron nail would give different results. So far, I've used copper sulfate, copper nitrate, copper carbonate, and cupric chloride. I've been trying to explain each. But I'm having difficulties accounting for one of them. For the trial involving copper nitrate, the reaction didn't occur. At some point, for curiosity's sake, I left the reaction ongoing for about 20 minutes and I eventually did notice a fine copper layer. Is there a reason copper nitrate is so unreactive in this case?
P.S: Separate question, but related to the same experiment. For the reaction involving copper carbonate, the nail instantly turned black. There was no change in mass before and after the experiment, so I have to conclude that nothing was plated, and that a chemical reaction took place instead. The nail turned dark black. It looked like copper oxide. Is that a fair assumption?