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Robert Copcutt · Guest

Fred Kasner wrote:
[quote]Salmon Egg wrote:
In article <48EA4FA4.5B14DCB3@sonic.net>,
Mark Thorson <nospam@sonic.net> wrote:

While in high school, I used ac drive for the standard electrolysis
apparatus used to demonstrate the process. To my surprise, The point
was to collect a small amount of mixture for an explosion. I was
collecting the mixed oxygen and hydrogen in a half pint milk
container. I found that the efficiency of gas production was much
smaller than if I used dc. This indicated to me that at 60Hz, the
electrolytic products recombined before molecular gasses could
evolve. I never followed that up.

Bill

Your apparatus was not producing a pure sinusoidal wave form.
[/quote]
You do not have enough information to know this. The wave form makes no
difference to this case anyway.

[quote]As such it
has small component of DC (fourier analysis shows this) and as such it
produced some small amount of H2 and O2. A pure sinusoidal wave form
will produce no gas at all save for some steam as the system heats up.
FK
[/quote]
What happens when an increasingly large voltage is applied between 2
electrodes is that first the double layer is charged up. When/if the
voltage gets high enough, electrochemical reaction starts. This value
depends upon the chemicals in the electrolyte and the electrodes.

When AC is applied some of the energy will go into charging and then
reverse charging the double layer. If the voltage is low enough, this is
all that will happen and no electrochemical reaction will happen. A
larger voltage will cause reactions. Whether or not the reaction
products reform the original reactants when the voltage polarity changes
will depend upon several things such as whether the products stay in
place long enough.

Fred Kasner · Guest

Salmon Egg wrote:
[quote]In article <a8NGk.1934$W06.479@flpi148.ffdc.sbc.com>,
Fred Kasner <fkasner@sbcglobal.net> wrote:

Because of passivation, my inclination is to agree that stainless steel
is not very good. But why is it unlikely to find decent electrode
material that is not platinum?

Bill

Hint: overvoltage, polarization, double layers at electrodes, etc.

FK

While I have heard of these factors and might even have a clue as to
what they mean, my profession has been outside the field of chemistry.
What is it about platinum that avoids such flaws from developing during
operation?

Bill

[/quote]
It is not so much the fact that platinum is highly conductive as the
fact that you can produce a layer on its surface that is highly
absorbant, very finely divided, and can be prepared with great purity.
That is referred to as platinized platinum.
FK

Fred Kasner · Guest

Dr. Leonard H. McCoy wrote:
[quote]If you are a real McCoy MD and still alive, I presume that you had to
take chemistry to get into medical school, Moreover, I presume that your
practice required some logical thinking involving chemical principles.
That is why it is incomprehensible to me that you could take the link
presented above seriously.

No association with medical field at all. The guy (Bones -- you have heard of
Star Trek, haven>t you?) was an *actor*.

The science (electrolysis) is still valid and the question -- how the persons
selling this can use SS to get the gasses -- still stands.

It helps to not get too carried away and simply focus on the question asked.

Thanks,
[/quote]
Stainless steel does a lousy job for electrolysis.
FK

Fred Kasner · Guest

Dirk Bruere at NeoPax wrote:
[quote]Fred Kasner wrote:
Salmon Egg wrote:
In article <48EA4FA4.5B14DCB3@sonic.net>,
Mark Thorson <nospam@sonic.net> wrote:

Platinum is not completely nonreactive, though
that doesn>t seem to be well known. Accidental
formation of compounds from platinum electrodes
led to the discovery of cisplatin, the first
modern anti-cancer drug.

http://chemcases.com/cisplat/cisplat01.htm

This is mighty interesting. There also is an article in Wikipedia on
cisplatin. Would you say that the cross linkage is related to the
typical catalytic properties of platinum?

Reading about the motivation to start these investigations seems
crackpot to me, It shows that crackpot ideas can have good outcomes
sometimes.

While in high school, I used ac drive for the standard electrolysis
apparatus used to demonstrate the process. To my surprise, The point
was to collect a small amount of mixture for an explosion. I was
collecting the mixed oxygen and hydrogen in a half pint milk
container. I found that the efficiency of gas production was much
smaller than if I used dc. This indicated to me that at 60Hz, the
electrolytic products recombined before molecular gasses could
evolve. I never followed that up.

Bill

Your apparatus was not producing a pure sinusoidal wave form. As such
it has small component of DC (fourier analysis shows this) and as such
it produced some small amount of H2 and O2. A pure sinusoidal wave
form will produce no gas at all save for some steam as the system
heats up.
FK

That rather depends on frequency.
I imagine that 0.00001Hz will produce quite a lot of gas.

[/quote]
Maybe. But how could you experimentally prove this. Since with such a
low frequency it is essentially a pulsed DC for half the wave and some
gas would have the ability to escape before the polarity changed. For
all practical purposes a very low frequency AC is more like a variable
DC if the period is very long.
FK

Dirk Bruere at NeoPax · Guest

Fred Kasner wrote:
[quote]Dirk Bruere at NeoPax wrote:
Fred Kasner wrote:
Salmon Egg wrote:
In article <48EA4FA4.5B14DCB3@sonic.net>,
Mark Thorson <nospam@sonic.net> wrote:

Platinum is not completely nonreactive, though
that doesn>t seem to be well known. Accidental
formation of compounds from platinum electrodes
led to the discovery of cisplatin, the first
modern anti-cancer drug.

http://chemcases.com/cisplat/cisplat01.htm

This is mighty interesting. There also is an article in Wikipedia on
cisplatin. Would you say that the cross linkage is related to the
typical catalytic properties of platinum?

Reading about the motivation to start these investigations seems
crackpot to me, It shows that crackpot ideas can have good outcomes
sometimes.

While in high school, I used ac drive for the standard electrolysis
apparatus used to demonstrate the process. To my surprise, The point
was to collect a small amount of mixture for an explosion. I was
collecting the mixed oxygen and hydrogen in a half pint milk
container. I found that the efficiency of gas production was much
smaller than if I used dc. This indicated to me that at 60Hz, the
electrolytic products recombined before molecular gasses could
evolve. I never followed that up.

Bill

Your apparatus was not producing a pure sinusoidal wave form. As such
it has small component of DC (fourier analysis shows this) and as
such it produced some small amount of H2 and O2. A pure sinusoidal
wave form will produce no gas at all save for some steam as the
system heats up.
FK

That rather depends on frequency.
I imagine that 0.00001Hz will produce quite a lot of gas.

Maybe. But how could you experimentally prove this. Since with such a
low frequency it is essentially a pulsed DC for half the wave and some
gas would have the ability to escape before the polarity changed. For
all practical purposes a very low frequency AC is more like a variable
DC if the period is very long.
FK
[/quote]
Exactly, but it would be a nice high school experiment to measure gas
evolution versus frequency, with a few other variable thrown in.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.onetribe.me.uk/wordpress/?cat=5 - Our podcasts on weird stuff

John Savage · Guest

Mark Thorson <nospam@sonic.net> writes:
[quote]Andrew Usher wrote:

On Oct 6, 11:49 am, Mark Thorson <nos...@sonic.net> wrote:

Platinum is not completely nonreactive, though
that doesn>t seem to be well known.

I think graphite electrodes are the least reactive.

No need to use graphite. Carbon will do.
All graphite is carbon, but not all carbon
is graphite. Carbon electrodes are stronger,
which is why they are used industrially.
[/quote]
I can>t speak for industrial processes, but I>ve noticed that a
carbon rod (as salvaged from a dry cell) is very quickly pitted
and roughened by use in a simple electrolysis of water cell. My
theory is that there>s something like cavitation going on as the
aqueous atoms explosively "expand" into a gas, and this relent-
lessly chips away at the electrode surface. One electrode
suffered more erosion than the other.
--
John Savage (my news address is not valid for email)

Salmon Egg · Guest

In article <0810110164243.11Oct08$rookswood@suburbian.com>,
John Savage <rookswood@suburbian.com.au> wrote:

[quote]I can>t speak for industrial processes, but I>ve noticed that a
carbon rod (as salvaged from a dry cell) is very quickly pitted
and roughened by use in a simple electrolysis of water cell. My
theory is that there>s something like cavitation going on as the
aqueous atoms explosively "expand" into a gas, and this relent-
lessly chips away at the electrode surface. One electrode
suffered more erosion than the other.
[/quote]
In a dry cell, carbon is used for the cathode. If carbon is used as an
anode in electrolysis, it can be anode. As an anode, it will be bathed
in all the species formed as OH- converts to O2. If you use a pair of
carbon electrodes do you find a difference in erosion between anode and
cathode?

In aluminum smelting, carbon anodes do get consumed. The conditions are
much hotter and drier than for water electrolysis.

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!

Kevin G. Rhoads · Guest

[quote]you can produce a layer on its surface that is highly
absorbant, very finely divided, and can be prepared with great purity.
That is referred to as platinized platinum.
[/quote]
Surface area is important, platinum black is neat -- but expensive.

Graphite is cheap and also useable, not as good, but ...

Dieter Britz · Guest

John Savage wrote:

[quote]Mark Thorson <nospam@sonic.net> writes:
Andrew Usher wrote:

On Oct 6, 11:49 am, Mark Thorson <nos...@sonic.net> wrote:

Platinum is not completely nonreactive, though
that doesn>t seem to be well known.

I think graphite electrodes are the least reactive.

No need to use graphite. Carbon will do.
All graphite is carbon, but not all carbon
is graphite. Carbon electrodes are stronger,
which is why they are used industrially.

I can>t speak for industrial processes, but I>ve noticed that a
carbon rod (as salvaged from a dry cell) is very quickly pitted
and roughened by use in a simple electrolysis of water cell. My
theory is that there>s something like cavitation going on as the
aqueous atoms explosively "expand" into a gas, and this relent-
lessly chips away at the electrode surface. One electrode
suffered more erosion than the other.
[/quote]
This is why, some decades ago, chlorine electrolysis people were
happy about the then new "dimensionally stable" titanium electrodes,
which did not fall apart. You can use stainless steel as the cathode
but as anode, it will probably dissolve, so you>re again stuck with
a noble metal like gold or platinum for the anode. Even gold is not
that noble in that context.
--
Dieter Britz (oldnob<at>yahoo.dk)

Salmon Egg · Guest

In article <gd4oa7$jtf$1@news.net.uni-c.dk>,
Dieter Britz <oldnob@yahoo.dk> wrote:

[quote]I can>t speak for industrial processes, but I>ve noticed that a
carbon rod (as salvaged from a dry cell) is very quickly pitted
and roughened by use in a simple electrolysis of water cell. My
theory is that there>s something like cavitation going on as the
aqueous atoms explosively "expand" into a gas, and this relent-
lessly chips away at the electrode surface. One electrode
suffered more erosion than the other.

This is why, some decades ago, chlorine electrolysis people were
happy about the then new "dimensionally stable" titanium electrodes,
which did not fall apart. You can use stainless steel as the cathode
but as anode, it will probably dissolve, so you>re again stuck with
a noble metal like gold or platinum for the anode. Even gold is not
that noble in that context.
[/quote]
If stainless steel were used as an anode in water electrolysis, would it
not get even more passivated? U can see that becoming problematical in
the sense that the passivating layer could become a resistive loss or
even insulating.

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!


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