What Are the Products of NaHCO3 Electrolysis?

[thomasc93]

Hello all!

We haven't had classes for the past few days and I've been bored, so I have been experimenting around with several different basic household electrolytes, two pure copper electrodes and a 12v power supply. The last combination of an electrolytic cell I tried was one with a solution of high (but unknown) concentration reagent grade NaHCO₃ and the cathode as well as the anode were the two pure copper plates. As I let the cell run it's course over a period of 2.5 hours or so, a light blue precipitate formed on the bottom of the jar and the solution went a deep blue and gases formed at both electrodes. Everything, including the water that I used to mix the sodium hydrogen carbonate solution with, was certified pure lab grade materials, so there were no contaminants in the process. I have thought about for a long time already as to what reaction could be going on here, and I have come up empty handed. All of my possible theories involve multiple reaction steps, but in the end they all do not work out. My last guess is that some kind of copper complex is maybe formed, but still, that sounds even a bit far fetched :-)

So could anyone give me a hint or point me in the right direction as to what is being formed in this reaction?

Thanks so much for your help!

 

[Cesium]

Copper hydroxide

 

[thomasc93]

That's what I thought, but isn't that insoluble? There was a bit of precipitate, but it really was just a thin layer on the bottom. The solution had some soluble salt dissolved in it. The solution was about the color of the cap of a Dasani bottle. Also, what happened with the sodium, you think?

Again, thanks.

EDIT: I don't think the color was due to Cu²⁺ in solution. The color isn't greenish-bluish, just very deep blue.

 

[Cesium]

Nothing would happen to the sodium- it just stays in solution as Na+. Cu+2 ions can be very deep blue.