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Topic: Hydrolysis and hydrogen production: byproducts?  (Read 6099 times)

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Offline Jaevko

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Hydrolysis and hydrogen production: byproducts?
« on: July 13, 2011, 05:05:30 PM »
First, sorry if this the wrong board, I wasn't sure where to put this.

So I'm running a current through distilled water with baking soda to produce hydrogen (to make stuff float :) ). I'm using carbon graphite electrodes and baking soda to avoid any dangerous gases like chlorine. Now its been almost a decade since I took chemistry classes and I'm wondering what other things are produced? I think CO2 is coming in somewhere from the baking soda? Does the graphite react as well?

The reason I ask is because if I'm collecting the hydrogen gas from one electrode, I want to know how pure it is. So please let me know what other chemicals are being produced due to the graphite and baking soda (and anything else I didn't think of, nothing else I think since it's distilled water) and please tell me if those chemicals are gases and which electrode they are coming off of. Thanks!!

Offline billnotgatez

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Re: Hydrolysis and hydrogen production: byproducts?
« Reply #1 on: July 14, 2011, 12:08:23 AM »
Sometimes the carbon electrodes disintegrate over time.

The stuff you are starting with seem safe to me
But
remember that hydrogen explodes fairly easily

I am not sure myself what are the products so please let us work this out together

what is the formula for the reactions expected
maybe we can start with the left side of the equation

by the way some people use sodium hydroxide with the distilled water, but it is caustic.


Offline Jaevko

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Re: Hydrolysis and hydrogen production: byproducts?
« Reply #2 on: July 14, 2011, 01:13:50 AM »
water electrolysis itself:
2 H2O(l) → 2 H2(g) + O2(g)

For other (unwanted) possible reactions, we also have the carbon in the graphite, NaHCO3 (baking soda) which is disolved in the water (so aqueous form I guess?), H2O, and the hydrogen and oxygen from the water's electrolysis

I know the products from other possible reactions are probably not dangerous, but I am afraid they will dilute my hydrogen! I'm really bad at chemistry (just never took the time to learn it well), more of a engineering/physics/math guy, so I can't go much further on my own than what I have above.  Thanks for your help !

Offline vmelkon

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Re: Hydrolysis and hydrogen production: byproducts?
« Reply #3 on: July 14, 2011, 02:35:27 PM »
I'm not a chem pro either.
With NaHCO3, the ions would be Na+ and HCO3-.
Na+ gets reduced to Na at the cathode.
The Na reacts with water to produce hydrogen.

At the anode, I have no idea what would happen. It is possible that you get CO2 and O2.

Producing hydrogen (humid) is easy.
If you want oxygen, I have used H2SO4 and lead electrodes. The electrodes last a long time.

Offline Jaevko

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Re: Hydrolysis and hydrogen production: byproducts?
« Reply #4 on: July 14, 2011, 05:58:22 PM »
Producing hydrogen (humid) is easy.

Producing hydrogen (not oxygen) is what I'm after. What did you mean by the above quote? Thanks!

Offline vmelkon

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Re: Hydrolysis and hydrogen production: byproducts?
« Reply #5 on: July 15, 2011, 11:17:14 AM »
I meant that the hydrogen will have humidity.
If you want to dry it, you could pass it through anhydrous CaSO4 or CaCl2 or CoCl2 or something similar.

Offline billnotgatez

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Re: Hydrolysis and hydrogen production: byproducts?
« Reply #6 on: July 21, 2011, 05:23:35 PM »
What I was thinking was we start out with the left side of the formula and see how to proceed from there

H2O + NaHCO3   ----->


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