Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
-----
So many problems with my science fair I don't know where to start
Q. I have had some problems with my science fair project. I wanted to see how long it would take to dissolve copper by process of electroplating. The copper dissolved, but a lot of things happened that I'm not sure were supposed to happen. I used insulated copper wire w/ the ends stripped to connect the brass key to the negative end of the battery and the copper strip to positive end. My vinegar ⇦in bulk on eBay or Amazon [affil links] and salt solution was very blue, and I remember someone on here saying that it was only supposed to be tinted blue. When I put the key in the solution there was and immediate heavy fizzing that gradually got slower after time. After a few hours the key started to have this red build up on it that grew and would break off and start growing again until the copper dissolved. This teal stuff somehow found its way to the stripped wire at the negative end, and that grew until the copper was dissolved. The battery is a 6 volt battery. I followed the instructions that I got out of the book, and would like to know if I did anything wrong.
Thank you for your time,
Renee [last name deleted for privacy by Editor]- Jax. FL, United States 2002
A. It sounds to me like your experiment was rather successful. The dark blue color means a lot of dissolved copper, which is probably good if you're trying to dissolve a whole copper strip.
The six volt battery is probably fine for dissolving copper but is probably too high for good plating onto the key. Even three volts is high for plating from a vinegar and salt solution in a beaker [beakers on eBay or Amazon [affil links] .
Successful plating onto the key, and quickest dissolution of the copper strip probably do not go hand in hand.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted,
I tried looking it up on the internet and in the library and I couldn't find anything. Thank you for your time.
Renee H- Jax., Florida
I'm not sure if there's still a question on the table, Renee. If you were attempting to dissolve copper, your experiment went fine. If you were attempting to plate out copper, the key was probably not clean enough and the voltage was probably too high.
The plating solution doesn't care about your intention to plate only on the key and not on the wire; it will plate on all exposed metal. An electronics store like Radio Shack will have plastic "heat shrink tubing" you can cover the wire with, and then shrink into place with a hair dryer ⇦this on eBay or Amazon [affil links] if you wish.
The "fizzing" is the generation of hydrogen on the key and oxygen on the copper caused by trying to plate faster than the metal ions can move. The result is that some of the electricity separates water into hydrogen and oxygen instead of depositing and dissolving copper. The fizzing grew slower as the solution got bluer because more of it went to plating. When you first started there was no copper in the solution, no blue color, so all of the electricity generated hydrogen.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q, A, or Comment on THIS thread -or- Start a NEW Thread