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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: base on April 07, 2004, 08:08:42 PM

Title: Electrolysis of Water
Post by: base on April 07, 2004, 08:08:42 PM

how on earth can you make hydrogen and some other gases using water and electricty?

Title: Re:I feel i am out of my depth!
Post by: Mitch on April 07, 2004, 09:39:44 PM

It's just a simple electrolysis. Can you be more specific?

Title: Re:I feel i am out of my depth!
Post by: gregpawin on April 07, 2004, 11:50:29 PM

Hmm... how much chemistry experience do you have?  I mean do you want to know about electrolysis or that the world is made of atoms and molecules?

Title: Re:I feel i am out of my depth!
Post by: One Armed Scissor on April 08, 2004, 09:47:26 PM

Hmmm... Could someone explain how it works to me because I have never understood how it works, only what happens.

I know that on the Redox table, there is:

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

but  that has a hydroxide instead of an oxygen, and that doesn't make much sense. (How does water get split by electricity?)

Title: Re:I feel i am out of my depth!
Post by: AWK on April 09, 2004, 01:38:17 AM

Electrolysis of water solution of strong base (eg NaOH or KOH)
Kathode: 4H₂O + 4e^- = 2H_2(g) + 4OH^-
Anode: 4OH^- = O_2(g) + 4e^-


Electrolysis of water solution of strong acid (eg H₂SO₄)
Kathode: 4H₃O⁺ + 4e^- = 2H_2(g) + 4H₂O
Anode: 6H₂O = O_2(g) +b4H₃O⁺  4e^-


Summary reaction in both cases:
2H₂O = 2H_2(g) + O_2(g)
And remember - anode and cathode compartments should be precisely separated during electrolysis to avoid explosion. Use direct curent about 3V.

Title: Re:I feel i am out of my depth!
Post by: One Armed Scissor on April 09, 2004, 06:39:29 PM

in other words, electrolysis cannot be done with water alone, and requires there to be a second reducing agent. Yes?

Title: Re:I feel i am out of my depth!
Post by: Scratch- on April 22, 2004, 11:30:17 AM

You can do electrolysis on water alone but it proceeds slowly. Adding an acid or base will increase conductivity of the solution while not usually affecting the gasses that are given off. You can do electrolysis by taking a battery and connect wires to it and dip the wires into the solution. You end up with hydrogen on one electrode and oxygen on the other. If you add another compound like sodium chloride for example it will break it apart and in this case forms hydrogen and sodium hydroxide on one electrode and oxygen and gaseous chlorine on the other.

Title: Re:Electrolysis of Water
Post by: Donaldson Tan on April 27, 2004, 08:09:08 AM

http://www.chemicalforums.com/index.php?board=4;action=display;threadid=64

You may make reference to the abovementioned link.