Question:
I was wondering what the bare minimum requirements for electrolysis
are. I want to create hydrogen out of water.
All the web pages I have seen are pretty sketchy on the specifics. I
know you need a battery connected to 2 metals dipped in a solution
containing ions. From the AP chemistry I remember in high school there
is a voltage drop you need (or created when run in reverse?). Is the
voltage supplied by the battery only there to create an electric field
across the 2 terminals (V = E*dl)? So that the each water molecule
experiences a small electric field across it and orients itself to it,
and then electrons flow using the same electric field generating battery
and brake H20 into H2 and O2? If that were the case, then the electric
field would vary as you seperate the anode and cathode, which nobody
seems to bring up in their explanations. The actual breaking apart of
2H20->2H2 + O2 is what I would like to know. I would like to know
EXACTLY what needs to happen. Thanks in advance.
Answer:
Put a DC voltage (a 1.5V cell should do it) across a salt solution (try
epsom
salt, MgSO4) or vinegar. DO NOT use table salt or you'll generate
toxic and globally warming chlorine gas. If you want H2 and O2 separate,
use 2 plastic bottles and connect with a salt bridge (the specifics are up
to you).
Overpotential calcs are a physical chem exercise... they vary from salt to
salt. If it doesn't work crank up the juice. Note that salt is not
necessary if you use a high-voltage DC field... I was trying to create a
spark underwater with a 300VDC source, and boy was I surprised to find
bubbles at the electrodes! btw, the anode side (oxidation) is where you
will find your corrosion problems. The cathode (reduction) is
comparatively stable.
