On Mon, 08 Dec 2008 14:59:56 -0600, Ignoramus25884
wrote:

With my 7 year old, I was trying to do a simple experiment, which is
extraction of oxygen and hydrogen from water by means of electrolysis.

To that end, we used magnesium sulfate (epsom salt) as electrolyte,
insulated copper wire with bare ends for electrodes, and a DC power
supply for electricity.

We collected hydrogen and oxygen into separate test tubes.

The part that did not work is that only one of the electrodes produced
any gas at all, and there was no gas coming out of the second
electrode. After a while of this, one test tube filled with gas and
the experiment stopped as the water was displaced from that
electrode.

So, my question is how come there is no gas on the second electrode.

I do not understand why this is so, given that both the experiment
book as well as Wikipedia says that magnesium should not oxidize?

The water acquired bluish tint.

WTF?

This probably isn't going to work well for you if you don't use
platinum as an electrode. You were getting hydrogen off of the
cathode, but the anode was reacting with the oxygen as soon as it was
produced, so you never saw it. (Obviously, you'd only gotten half as
much as the hydrogen, anyway.)

Maybe these guys can help.....
http://www.carolina.com/product/phys...Matches&page=1
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Gene wrote:
On Mon, 08 Dec 2008 14:59:56 -0600, Ignoramus25884
wrote:

With my 7 year old, I was trying to do a simple experiment, which is
extraction of oxygen and hydrogen from water by means of electrolysis.

To that end, we used magnesium sulfate (epsom salt) as electrolyte,
insulated copper wire with bare ends for electrodes, and a DC power
supply for electricity.

We collected hydrogen and oxygen into separate test tubes.

The part that did not work is that only one of the electrodes produced
any gas at all, and there was no gas coming out of the second
electrode. After a while of this, one test tube filled with gas and
the experiment stopped as the water was displaced from that
electrode.

So, my question is how come there is no gas on the second electrode.

I do not understand why this is so, given that both the experiment
book as well as Wikipedia says that magnesium should not oxidize?

The water acquired bluish tint.

WTF?

This probably isn't going to work well for you if you don't use
platinum as an electrode. You were getting hydrogen off of the
cathode, but the anode was reacting with the oxygen as soon as it was
produced, so you never saw it. (Obviously, you'd only gotten half as
much as the hydrogen, anyway.)

You don't get weird secondary reactions if you stick with the lowest
possible voltage.

Use the largest flattest electrodes you can, as close as possible. The
lower the resistance of the cell, the more current flow you get- which
means you get more gas.

you can also use baking soda, it's cheap and won't corrode everything near
you.

I've made gas generators in 500Ml nalgene squirt bottles. If you run
enough current though it you ge the water to boil and end up with more
steam than gas, which is a problem if you want hydrogen and oxygen for a
fire.

http://www.spirig.com

has a section about how their electroyltic cells work. The torches they
make are pretty nifty as well. The amount of heat they produce for the
size of the flame is incredible, especially for soldering.

Cydrome Leader writes:

Use the largest flattest electrodes you can, as close as possible. The
lower the resistance of the cell, the more current flow you get- which
means you get more gas.

Remember, he's trying to collect the gas in a test tube.