# What are we seeing in this AC salt-water copper-wire experiment?

There's a highly watched video on YouTube by "ElectroBoom" on the effects of passing AC (not DC) current through salt water. The water gets cloudy and at the end of the video we can see one of the copper wires has been eaten away by the process.

Is there really "a reaction of the copper with the salt in water" as the author of the video claims? Or is it a pure physical process where the copper "boils off" the wire?

• SAFETY - Using the name ElectroBoom gives me a bad vibe about this. By using alternating current you're getting both hydrogen and oxygen at each electrode. Together the two gases do react explosively. Don't do it... – MaxW Apr 10 at 13:25
• @MaxW: I take your point about safety, but I haven't heard of AC current causing outright explosions in water. Although if that's the case, it would be an interesting part of the answer. – Fizz Apr 10 at 13:37
• @MaxW: presumably if the current was high enough it could have the same effect as dropping something very hot in water, which can result in a vapor-related explosion, e.g. youtu.be/PDRWQUUUCF0?t=123 – Fizz Apr 10 at 13:48

$$\ce{Cu^0 + 2OH- -> Cu^2+ + 2e- + 2OH- -> Cu(OH)2 + 2e- -> CuO + 2e- + H2O }$$ (expanded for clarity, not a reaction mechanism)
• @Fizz There may be some $\ce{Cu2O}$ produced as well which is reddish, the video isn't very clear. – A.K. Apr 10 at 22:30