by waterbard » Tue Dec 12, 2006 4:27 pm
According to wikipedia:
The electric current disassociates water molecule into hydroxide (OH-, and hydrogen H+, ions.
In the electrolytic cell, at the cathode, hydrogen ions accept electrons in a reduction reaction that forms hydrogen gas:
Cathode (reduction): 2H2O(l) + 2e- => H2(g) + 2OH-(aq)
At the anode, hydroxide ions undergo an oxidation reaction and give up electrons to the anode to complete the circuit and form water and oxygen gas:
Anode (oxidation): H2O(l) => O2(g) + 4H+(aq) + 4e-
hence decomposing water into Oxygen and Hydrogen;
Overall reaction: 2H2O(l) => 2H2(g) + O2(g)
AND:
As pure water conducts electricity very poorly, a water-soluble electrolyte must be added to the electrolysis cell to close the circuit. The electrolyte dissolves and disassociates into cations and anions (positive and negative ions) that carry the current. Electrolytes are normally acids, bases, or salts.
Care must be taken in choosing an electrolyte, since an anion from the electrolyte is in competition with the hydroxide ions to give up an electron. An electrolyte anion with less standard electrode potential than hydroxide will be oxidized instead of the hydroxide, and no oxygen gas will be produced. A cation with a greater standard electrode potential than a hydrogen ion will be reduced in its stead, and no hydrogen gas will be produced.
The chemistry of electrolysis isn't as simple as oxygen and hydrogen. There are different states of matter. During electrolysis, you have hydrogen, oxygen, both in gas molecule form, and hydroxyl, which is aqueous. You also have hydrogen ions that are in an aqueous state as well. Your pH is going to fluctuate.
Btw, high voltage does not produce heat waste when pulsed properly. High current has a higher probability for heat.
Bzzz...