[NewCandle] Getting started with aluminum foil

[Keith Nagel]

Hey Nick.

All this begs the question, "What is the rate determining step"
I assume under neutral/alkaline conditions, that the corrosion
is occuring at distinct sites, due to the insolubility of the
oxide layer in solution ( we see all the oxide collecting
at the bottom of the container ). Are the sites clogged with
OH's? Or is H2 gas blocking the pits? Or something else???

I'll take a guess that the peroxide may be clearing the
excess H from the corrosion sites, but you must have had
a reason for adding it: why? Extra protons ( HCl for these
salt experiments ) would hasten the dissolution of the
oxide film on the aluminum. As you might guess, I am interested
in nitrate corrosion.

One thing the literature says about corrosion on aluminum is
that it is very sensitive to dissolved oxygen. More O2 in solution,
more corrosion.

I can do another test which may be of interest. I have a
nice Ag/AgCl half potential electrode which I can use to
measure the potential of the aluminum w/ respect to the
solution. I'll set up a special cell with a pigtail of
aluminum out of the flask so I can make the measurement.

K.

-----Original Message-----
From: newcandle-bounces at ipdiscover.com
[mailto:newcandle-bounces at ipdiscover.com]On Behalf Of Nick Reiter
Sent: Thursday, April 22, 2010 11:46 AM
To: New energy for the new world.
Subject: Re: [NewCandle] Getting started with aluminum foil


Hi Keith,

> All sounds OK but for one missing element. The rate of
> reaction
> and hence power output, is proportional to temperature.
> Using
> your model it is as if the resistor was nonlinear, like
> an arc channel. The arc temp rises, its resistance lowers,
> more current flows, causing more power to dissipate,
> further
> raising the temp, etc etc. In the arc what limits the
> current flow is the max current available from the power
> supply. What limits the rise in the aluminum corrosion
> under this
> runaway condition is the max water temp, 100C.

************Indeed, correct.  I like the analogy.

> This feedback process requires a certain fixed level of
> power output to overcome the losses and start the snowball
> rolling. Our current tests all have lots of losses so
> it takes quite a bit of reacting metal to get enough
> heat to start the process. Using a vacuum flask will
> help in this regard. So would heating the water initially.

*************Heres a couple of tech-hints and nonsequiturs that might be
meaningful.  One of the recent recipes was the usual 5 liters of water, but
with 20ml of 30% H2O2 added.  This really seemed to be a kicker - the "pure"
distilled water only reactor took over a week to start hydrolyzing visibly
(though it reached a peak performance roughly analagous to the salt water
version) - however the addition of the H2O2 kicked off the whole process in
a time-accelerated way.  Steady small bubble streams were beginning in less
than 24 hours, and full peak bubbling was about 48.  So I had come to see
the peroxide doped bucket as sort of a "fast track" version, though of
course it reached terminal oxidizing and petered off quicker too.

Now I then started an identical bucket reactor, but placed it in an old lab
refrigerator where it chilled to about 5C.  As opposed to 20 to 25C.
Arrhenius would predict that it should have slowed down the visible signs of
any hydrolysis by a factor of 4 - 4 days instead of 1.  However it was
nearly 8 days out before very slight bubble stream formation began, and even
now, proceeding at nary more than a trickle at T+11 days.

> Perhaps after I collect some hard data I can take a stab
> at mathematically modelling the system. I predict it
> will look a lot like the nonlinear arc process I describe
> above, with the first notable difference being the
> limiting conditions.
>
> Does this make sense to you?

*************That would be awesome!  I would agree with your prediction.

> > Last night I took my two small vacuum flasks and charged
> them each with 200mL of salt solution. Into one was dropped
> a
> 4.2 sqr ft roll of foil. The other has no metal and serves
> as a temp reference. We shall see what happens in the next
> few days. It still is intriguing to me that the folded
> metal
> roll I did a few days ago is reacting but not floating.
> I think this is an important geometric consideration;
> aside
> of the reaction rate test I initially designed for this
> experiment.

**********Interesting.  Are any versions actually producing visible
"continuous" small bubble streams, as opposed to slowly evolved clinging
bubbles?

~n





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