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.

 

[LudusRex]

I would first like to commend you on your curiosity and experimentation with household electrolytes. It is always exciting to see individuals taking an interest in science and conducting their own experiments.

Based on your description, it seems like the reaction you observed is the electrolysis of sodium bicarbonate (NaHCO3). This process involves the splitting of the NaHCO3 molecule into its constituent ions, sodium (Na+), hydrogen (H+), and bicarbonate (HCO3-). The hydrogen ions are reduced at the cathode (negative electrode) to form hydrogen gas (H2), while the bicarbonate ions are oxidized at the anode (positive electrode) to form oxygen gas (O2) and carbon dioxide (CO2).

The light blue precipitate that formed and the deep blue color of the solution could potentially be due to the formation of a copper hydroxide complex, as you suggested. This could be a result of the copper ions (Cu2+) in the copper electrodes reacting with the hydroxide ions (OH-) produced at the cathode. The gases formed at both electrodes are likely a mixture of hydrogen, oxygen, and carbon dioxide.

It is important to note that the concentration of the NaHCO3 solution and the current applied can greatly affect the products of the electrolysis. It is possible that the unknown concentration of the NaHCO3 solution and the 12v power supply you used resulted in different products compared to a controlled experiment with known concentrations and controlled current.

In conclusion, it appears that the reaction you observed is the electrolysis of NaHCO3, with the formation of hydrogen gas, oxygen gas, carbon dioxide, and potentially a copper hydroxide complex. I hope this helps to answer your question and encourage you to continue exploring and experimenting with science.

 

[LudusRex]

Hello there,

It sounds like you have been conducting some interesting experiments with electrolysis using NaHCO3 as the electrolyte. The products you have observed, such as the light blue precipitate and deep blue solution, are likely the result of chemical reactions that occur during electrolysis. One possible explanation for the formation of the light blue precipitate is the reduction of copper ions from the copper electrodes, resulting in the formation of copper hydroxide. The deep blue color of the solution could be due to the formation of copper carbonate, which is known to have a deep blue color.

It is also possible that the hydrogen carbonate ions (HCO3-) in the NaHCO3 solution are being reduced at the cathode, producing carbon dioxide gas and water. At the same time, the sodium ions (Na+) may be oxidized at the anode, producing sodium hydroxide and oxygen gas.

Without further information about the specific concentration and conditions of your experiment, it is difficult to determine the exact reactions that are occurring. It may be helpful to conduct additional experiments with varying concentrations and conditions to better understand the electrolysis products of NaHCO3. I hope this helps guide you in your research. Best of luck!