Electrolyte for electrolysis of water

[livefree75]

I've been wanting to build my own electrolyzer to produce hydrogen and oxygen, but I'm having difficulty choosing an electrolyte, and have seen many conflicting sources. What would be the best and most common electrolyte to use for this application?

[sevenperforce]

59 minutes ago, livefree75 said:

I've been wanting to build my own electrolyzer to produce hydrogen and oxygen, but I'm having difficulty choosing an electrolyte, and have seen many conflicting sources. What would be the best and most common electrolyte to use for this application?

Epsom salt. Sodium chloride tends to corrode.

Also, be careful. GOX and GH₂ are not that energetic compared to most rocket fuel but they are rather horribly energetic compared to ordinary household items.

Edited April 29, 2016 by sevenperforce

[shynung]

Also worth mentioning is that GH₂ burns without a visible flame. Place thermometers (or IR cameras) around the vicinity of the equipment, else you might not realize there's a fire until it's too late.

[PB666]

1 hour ago, sevenperforce said:

Epsom salt. Sodium chloride tends to corrode.

Also, be careful. GOX and GH₂ are not that energetic compared to most rocket fuel but they are rather horribly energetic compared to ordinary household items.

Also generates chlorine gas instead of oxygen

[sevenperforce]

1 minute ago, PB666 said:

Also generates chlorine gas instead of oxygen

Chemistry was never my strong suit.

[PB666]

You don't need an electrolyte per say, but your salt bridge needs to be relatively close to the electrode, wide and semipermeable membrane that is impermeable to the solute, but permeable to protons, presumbably a salt. Because of the low conductivity of pure water (18 megaohm), The salt bridge should also have a relatively high buffering capacity. If you add chloride to the device you will get chlorine oxidation, which is dangerous. 

This particular style replaces the platinum electrode with a carbon polymer, one of these corrosions resistent new age materials we talk about. In this particular design the protons need to flow to the membrane, so either there is a laminar flow in each side of the chamber or the electrodes are fairly close. A high output system will produce alot of bubbles and this will stir the system.

Oxygen can be made per say using photosynthesis, essentially you need to feed bicarbonate into the system using something like ammonium carbonate/carbon dioxide (which can be made by essentially trapping the gas from the slow addition of baking soda to muriatic acid, the algae then convert CO2 to O2, in pretty good amounts.

[softweir]

3 hours ago, PB666 said:

muriatic acid

a.k.a. by the much more common name of hydrochloric acid. Why call it muriatic acid?

[PB666]

Muriatic acid is the common, trade name, for non-fuming forms of hydrochloric acid. You can buy it by that name at hardware stores. It by name, frequently is less concetrated and is at or below technical grade purity compared  hydrochloric acid proper. The first is used in industries where the product is used for pickling, such as metals and was so name back inthe 1750s, and typically below 25% (originally extracted from the stomach of animals, typically around pH of 2, 100th molar). The second is used in synthesis or processes that require a higher level. 

If you want to use  highly concentrated 'fuming' HCL, well, just add aluminum shavings and youll get hydrogen gas. Note that i cannot condone this, the last person who did this sent several folks to the school nurse, and its not very environmentally friendly. 

 

[lajoswinkler]

Pinch of sodium sulfate or sodium hydroxide unless you use platinum electrodes (and I doubt you do LOL). Don't use excessively large currents because you'll get some ozone at the anode and you'll heat the electrolyte causing lots of warm vapor to enter you system.

 

PB666, concentrated hydrochloric acid is NOT to be used for making hydrogen. Dumping aluminium in it will cause a delayed violent reaction that will produce copious amounts of hydrogen chloride and hydrochloric acid mist. It will turn into gray, corrosive foam that will solidify like lava after it cools down.

HCl in any concentration is really not the best thing for making hydrogen as it's volatile, necessitating gas scrubbers to remove the fumes.

 

Also, what the hell is GH2 and GOX? 

Edited May 1, 2016 by lajoswinkler

[softweir]

1 hour ago, lajoswinkler said:

Also, what the hell is GH2 and GOX? 

Gaseous H2 and Gaseous O2.

[lajoswinkler]

43 minutes ago, softweir said:

Gaseous H2 and Gaseous O2.

There's absolutely no need for that. In no circumstances will we get solid or liquid hydrogen and oxygen from electrolysis of water. It's a silly pleonasm from US education system.

[softweir]

2 hours ago, lajoswinkler said:

There's absolutely no need for that. In no circumstances will we get solid or liquid hydrogen and oxygen from electrolysis of water. It's a silly pleonasm from US education system.

Indeed, and I couldn't agree more! But the pleonasm needed to be explained.

[Atlas2342]

On 29/04/2016 at 7:13 AM, softweir said:

a.k.a. by the much more common name of hydrochloric acid. Why call it muriatic acid?

A.K.A the Horribly Evil Stuff* That Melts Through Your Flesh^TM

^{*(as with some evil and corrosive substances)}

[sevenperforce]

On 5/1/2016 at 8:26 AM, lajoswinkler said:

There's absolutely no need for that. In no circumstances will we get solid or liquid hydrogen and oxygen from electrolysis of water. It's a silly pleonasm from US education system.

I only called them GOX and GH2 in contrast to LOX and LH2 because this forum has a LOT of discussion of the latter and not much of the former.

[QuesoExplosivo]

11 minutes ago, Atlas2342 said:

A.K.A the Horribly Evil Stuff* That Melts Through Your Flesh^TM

^{*(as with some evil and corrosive substances)}

Hydrochloric acid is pretty tame as far as acids go. I've occasionally spilled some 12 M HCl on my skin; as long as it's washed off within a few seconds, it's fine. Getting it in your eyes, or breathing the fumes, are the real problems. Many other acids (hydrofluoric, trifluoroacetic, concentrated nitric or sulfuric, etc.) will cause burns pretty much instantaneously.