Electrolysis - Is there a solution to why no oxygen is produced at the anode?

I'm currently doing an electrolysis experiment. I have a large container and have added 3.5 Litres of tap water and 5% salt to the solution. I'm using copper as my electrodes (copper pipe) and am using 12V DC for my voltage. While conducting the experiment, I noticed that no oxygen was produced at the anode, however in contrast, there was a significant production of hydrogen at the cathode (confirmed this with a 'pop' test). I also noticed that the water turned a blue colour. I also reduced my salt concentration to even as little as 0.5%, however still found that no oxygen was produced.

The same thing also occured whjen I tried using pencils as my electrodes though instead the water turned red/orange in colour. I also attempted using baking powder, though found that 1 teaspoon would not dissolve in the water, and the same thing occured that no oxygen was produced.

Is there a solution to this problem besides changing my electrode?

Answer:
italia4ever,

Indeed, the reason you could not get O2 gas using copper as the electrode is that copper is more easily oxidized than oxygen, and thus you see the blue color of Cu2+ ions dissolving from your electrode and going into solution. It is also true that chlorine will oxidize more easily, so you cannot use salt as the electrolyte if you want to get oxygen gas.

I'm wondering if the reason the solution turned orange with pencils is that there was still wood on them, and the wood started oxidizing and leaving organic residue in the water. Here's what I recommend: Use bare pencil lead (graphite) as the electrodes, and make sure there is nothing left on them. Instead of salt (which will produce Cl2 gas) or baking soda (which is not very soluble), use epsom salt (MgSO4). It should be easy to find at the store, very soluble, and not create any problems. Best of luck!
12vdc at how many miliamps less than 30?
wall wart ps or a small battery?

copper oxides can form rather than express
o2 as a gas,,,, i had to go and buy nickle plates on e bay and even those have polarity coatings to prevent formations of
oxides and hydrates which inhibit gas production by attaching to calcium and other deposition salts

salt is a sticky deal too, you could outgas clorine gas and make yourself and other sick, all the people i talk to use a mile base like baking soda for initial tests and as they get more experenced they graduate to lye

you need to get into a group for a little saftey, alot of safty actualy , and i would stop untill i had some serious understanding of what was going on
haha i know why you can't get oxygen using copper as electrodes.
because at the anode copper itself was oxidised!! and your solution turned blue because of the Cu2+ cations formed in this process.

btw which salt did you use? i never tried electrolyzing water but i know you'll get chlorine if you use salts that contain Cl-.
i think NaSO4 would be better.

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