Electrolysis Electrodes

[Silencer]

I am making a simple electrolysis machine from some PVC pipe (i hope this isn't too reactive) and would like to know what kind of electrodes to use.

 

Gold is pretty much out, but i've heard a lot about carbon. What type of carbon should I use and where can I get it? Is the graphite from a pencil sufficient?

 

Also, to me more power and more speed = better, so is using the electricity from my house OK, or should I just use some batteries?

 

Thanks.

[YT2095]

what are you planning on as your electrolyte?

[Primarygun]

Either sulphuric

acid (dangerous) OR sodium sulphate(harmless),right?

[YT2095]

in that case plain old stainless steel will work perfectly well

[Silencer]

Well right now I just want to make some H2 and O2 out of water to mess with it.

 

Hopefully there will be some Chromium solutions in the future.

 

Also, could pure N2O be formed with some kind of ammonia and water mixture?

 

edit: I like how the ranks on these forums work (starting as a lepton and going to larger and larger things). It's amusing.

[YT2095]

acidulated water with H2SO4 will do yer H2 and O job for you perfectly

and yes use stainless steel sheeting for that

 

for N2O from ammonia, you`ll need more than just electrolysis.

 

heating of Ammonium Nitrate will liberate N2O however

just be realy carefull!

[Silencer]

Would you mind explaining why some metals are better to use than others for the electrodes? I just like understanding what is actually going on. If you don't feel like it then just tell me and I will search google and not wast your time

 

Thanks.

[YT2095]

some metals will react with certain electrolytes.

the idea is to have NO reaction take place (unless that`s what you want, but you lose the electrode!).

[Gilded]

Btw, why hydrogen forms on the cathode and oxygen on the anode (or the other way around, lol)? Something to do with electronegativity? My knowledge about electricity is VERY limited. :/

[Silencer]

^I thought it was because the H+ ions get attracted to the negative electrode and the O-- get attracted to the positive?

[Silencer]

YT, you suggested sulfuric acid as the electrolyte... will this work a lot faster than just plain water?

 

Is using my house electricy OK or is that overkill/dangerous?

[Primarygun]

All in all, acid will decompose in water to give mobile ions, Such as H3O+ , SO4 2-, SO3 2-, NO3-............... In brief, acids are electrolytes. They conduct electricity well due to the presence of moblie ions. It conducts due to the movement of mobile ions.

Pure water merely has mobile ions. Since it is a molecule, the electronegativity of oxygen and hydrogen is not differ to much, the probability of water molecules pull off an ion out from an other water molecule is low. Hence, water is not a electrolyte.

Adding small amount of dangerous sulphuric acid make it perfect.

By the way, YT, how to extract potassium from its own ore?

[Primarygun]

By the way, I think using domestic electricity from power station is too dangerous.

Better use cells. They are enough and safer.

[Silencer]

Are there any relationships between voltage, current, properties of the electrolyte, and such that I should be aware of for accuracy's sake?

[YT2095]

the overall resistance of the cell will be quite low at 1`st and increase a little as gas is produced. pluging it into the house electrics will most certainly blow a fuse at minimum.

AC current is counter productive also.

 

the acidified watter need only be a few percent sulphuric, less concentrated than vinigar!

 

be very carefull with this apparatus though, the H and O gasses form an explosive mixture, so make sure to incorporate a valve system so it cant backup into your cell. I know a few lads that made some of these, using solar power as the source, it was certainly enough to power a small engine

[Silencer]

I can't wait to make it and take some pics; I have all the parts ready. Only problem is that it's not clear so you can't see what's going on.

 

BTW, where can you get sulfuric acid? Home Depot? Or are there any other more common acids that will work (HCl is easy to get but then it will be an O and Cl mix at the cathode, which won't be nearly as fun/safe).

[budullewraagh]

you want to use sulfuric, which i cant find at local stores but some can. ive heard it's really poor though. charge old car batteries and filter out the insoluble lead sulfate and you should have 30-40% conc sulfuric

[5614]

Btw, why hydrogen forms on the cathode and oxygen on the anode (or the other way around, lol)? Something to do with electronegativity? My knowledge about electricity is VERY limited. :/

this shows electrolysis of water

 

 

this shows:

 

oxygen is attracted to the postivie side, H to the negative side

 

 

this is because:

 

At the anode, water is oxidized:

2H2O --> O2 + 4H+ + 4e-

 

At the cathode, water is reduced:

4H2O + 4e- --> 2H2 + 4OH-

 

 

 

The net reaction: 2H2O --> 2H2 + O2

 

 

 

for the O to be oxidised there needs to be a loss of an electron, this happens at the positive electrolyte (or rod thing leading from battery!)

 

for the H to be reduced there needs to be a gain of electrons, this happens at the negative end of the electrolyte.

 

hence O goes to the anode (positive leg) (for oxidation) and H goes to the cathode (negative leg) (for reduction).

[5614]

Are there any relationships between voltage, current, properties of the electrolyte, and such that I should be aware of for accuracy's sake?

 

voltage: effectively higher voltage the more product you get (MUST BE DC)

current: same as voltage, as it is the current which is a flow of electrons and it is the electrons doing the electrolysis you want a high current too.

electrolyte: this varies with what you are doing electrolysis on..... for water, graphite rods are good.

[Silencer]

Thanks, 5614. I'm going to experiment with wiring the batteries in a combination of serial and parallel circuits to see which works best.

[Gilded]

"electrolyte: this varies with what you are doing electrolysis on"

 

I'd imagine you shouldn't have anything that can react with the H+ or OH- when doing water electrolysis?

[raivo]

One of rather good electrolytes that can be used to make H2 and O2 is solution of NaOH. It's strong point is that amount of NaOH will never decrease due to secundary reactions that take place. You only have to add water, no mater how much you use your electrolyser.

 

If you use sulphates or H2SO4 as electrolyte it is all easy as long as current is low (maybe less than 5 ampers), on high currents sulphate ions start to decompose and you get some SO2 or SO3 too. ( I have forgoten what exactly happens. )

[5614]

ok and please do post the results, it is interesting and useful to us here!

 

also a bigger surface area of the electrolyte will be better (to an extent) as it will allow for more flow of electrons aka less resistance!

 

also H2O isnt the best conductor, mixing salt in with it greatly improves conductance and therefore you get a better output however saltwater produces different gasses to water, so im not sure how much salt you can put in until you start getting O and Cl(from saltwater) opposed to O and H (from water).

[Gilded]

"also H2O isnt the best conductor, mixing salt in with it greatly improves conductance and therefore you get a better output however saltwater produces different gasses to water, so im not sure how much salt you can put in until you start getting O and Cl(from saltwater) opposed to O and H (from water)."

 

I guess if you just want the hydrogen, you could use even quite a bit of salt without a problem as the Cl goes to the anode, doesn't it?

[5614]

i thought that when you have a saltwater (brine) solution and electrolyised it you got Cl and O

 

(i'll just check)