Building H20 electrolysis cell, need advice

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Discussion Overview

The discussion revolves around the construction of an oxyhydrogen welding torch using electrolysis to split water into hydrogen and oxygen. Participants explore the necessary components, safety considerations, and suitable electrolytes for the electrolysis cell, focusing on both effectiveness and safety in case of spills.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant outlines their plan to create an oxyhydrogen welding torch, specifying the use of stainless steel electrodes and a controlled low-pressure environment.
  • Concerns are raised about the use of table salt as an electrolyte due to the potential production of chlorine gas during electrolysis.
  • Another participant questions the mechanism by which table salt could emit chlorine gas, seeking clarification on its behavior during the electrolysis process.
  • A suggestion is made that strong bases like NaOH or KOH, or sulfuric acid, could serve as effective electrolytes, noting their relatively low resistance and the safety of diluted solutions.
  • One participant mentions sodium carbonate (Na2CO3) as a possible alternative electrolyte, seeking confirmation on its suitability.
  • There is an acknowledgment of the need for safety precautions when handling strong electrolytes, with mixed views on their danger levels after a spill.

Areas of Agreement / Disagreement

Participants express differing opinions on the safety and effectiveness of various electrolytes, particularly regarding table salt and its potential to produce chlorine gas. The discussion remains unresolved on the best choice of electrolyte and the associated safety concerns.

Contextual Notes

Participants have not reached a consensus on the safest electrolyte to use, and there are unresolved questions about the conditions under which chlorine gas might be produced during electrolysis.

Who May Find This Useful

Individuals interested in DIY electrolysis projects, oxyhydrogen applications, or safety considerations in chemical processes may find this discussion relevant.

axemaster
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I don't happen to have any welding equipment available to me, so I have decided to make an oxyhydrogen welding torch. That basically involves splitting water by electrolysis, running it through a tube with a blowback arrestor and burning it on the other end. I have read that the voltage should be 1.5-2 volts, and I expect to be running something like 50-150 amps. I'll be using a variac to control the voltage from the wall, then running it through a step-down transformer and finally through a heavy duty rectifier to make it DC.

The electrolysis cell will use stainless steel electrodes, probably thin sheets of alternating positive and negative voltages. The whole setup will be under low pressure, not more than 2-3 psi at most, and the temperature will be below boiling.

Having done some research, I am aware that I will need to add an electrolyte to the water to make it conductive enough. However, I would like the water to still be "safe", i.e. not dangerous to the human body in case it should spill or something. I know I can't use table salt since it would emit chlorine gas.

Are there any safe electrolytes I can use? If not, then what is the safest relatively speaking?

By the way, if I have overlooked anything else, or if you have any advice, please let me know. I want to do this in a safe way. Thanks!
 
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Why would spilled water with table salt emit chlorine gas? Does it build up in the water during electrolysis?
 
Drakkith said:
Why would spilled water with table salt emit chlorine gas? Does it build up in the water during electrolysis?
I meant chlorine gas produced during operation coming out with the hydrogen and oxygen in the torch flame.

Am I wrong? I was under the impression that it was dangerous to use table salt, but if not then I'll be a happy camper. Does anyone know how much salt I can mix in before a significant amount of chlorine gas is produced?
 
Ah ok that makes more sense. The way you worded it I thought you only meant make it safe in case the water spilled out or something. My knowledge on electrolysis isn't very good, so I really don't know if it would emit chlorine gas or not.
 
Strong bases (NaOH, KOH) and sulfuric acid are the best I can think of. There will be no other electrolysis products but oxygen/hydrogen, and their solutions have relatively low resistance thanks to the presence of either H+ or OH- (so you need lower voltage and they heat less). Are they dangerous after a spill? Yes and no, you don't need them highly concentrated, so if treated with a reasonable attention they are not more dangerous than power tools in the workshop.

But I have a gut feeling we are reinventing the wheel here.
 
My friend told me I should use Sodium Carbonate (Na2CO3).

Is there anything else I have forgotten here or am I pretty well covered?
 

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