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Help ! (about Nernst equation)
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Lasse Murtomäki
science forum beginner


Joined: 17 Jun 2005
Posts: 35

PostPosted: Wed Apr 26, 2006 12:42 pm    Post subject: Re: graphite Reply with quote

Yes, it probably was off-scale.

--
Lasse Murtomäki
Helsinki Univ. Tech.
Lab.Phys.Chem.Electrochem.
lasse.murtomaki@tkk.fi
"Dieter Britz" <britz@chem.au.dk> wrote in message
news:e2nlm3$vue$1@news.net.uni-c.dk...
Quote:
Lasse Murtomki wrote:

Is there any value for the relative permittivity of graphite. It sure is
a
good conductor, but is the value infinite? I am testing a material
probing
kit and got an infinitely high value for a graphite disk.

Doesn't that just mean, it's off-scale? To be expected, I
guess, for a conductor.
--
Dieter Britz, Kemisk Institut, Aarhus Universitet
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Peter_Hunnt@yahoo.com
science forum beginner


Joined: 07 Mar 2006
Posts: 6

PostPosted: Wed Mar 08, 2006 7:13 pm    Post subject: Re: RF...? Reply with quote

What I'm trying to fing out is... Is it possible to get some compound
or chemicals. Alter their structure so that the chemical or compound
will be only affective when someone sends a RF wave. I don't know if I
can say it this way ..but polarize, make it only react when the
specific RF is send.
Lets say a chemical that normally when put in a sea water turns the
water red. Now is it possible to somehow alter the chemical that when
put in the water will not turn the water red but only when you transmit
a specific radio frequency wave will turn the water red?

peter_hunnt@yahoo.com
Thank you
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Evgenij Barsukov
science forum Guru Wannabe


Joined: 09 May 2005
Posts: 137

PostPosted: Wed Mar 08, 2006 4:21 pm    Post subject: Re: RF...? Reply with quote

Peter_Hunnt@yahoo.com wrote:
Quote:
Hello
I don't know what is the best way to ask this, so I'm going to say it
in my plane language.
Is it possible to change the structure of chemicals with radio
frequency..?

That is a controversial topic, it depends how you define "chemicals".

What is clear is this:
- you can not break chemical bonds by RF (not enough energy)
- RF can heat up materials, which eventually can break weaker hydrogen
bonds (but this is not specific to RF, any heating can do that).

One caveat:
- heating is specific (higher or lower) depending on a nano-scale size
composition (more electrically conductive will heat up more). For
example one nano-scale aggregate (say a chromosome) can be heated more
than other (say membrane, or ribosome). This way temperature gradients
on nano-scale can be created.

This can (but have never been proven to) have effect on living
organisms, as temperature gradients _inside_ a cell can cause
some unusual concentration gradients disrupting usual processes.

Same way on larger scale, temperature gradients between tissues
(for example between nerves and fat or muscle tissues) could
cause unusual sensations and might again cause unusual processes
if strong enough.
Note that temperature gradients are already present in the organism
but they are generally in the direction from cooler (skin) to heater
(muscles).

To summarize - effect on chemicals is well understood,
while effect on continuously dynamically changing nano-scale composites
such as life objects is more subtle and still open for discussion. It
might well be that at some level RF will cause enough temperature
gradients to disrupt some processes.

Regards,
Evgenij
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jpsmith123@yahoo.com
science forum beginner


Joined: 29 Dec 2005
Posts: 11

PostPosted: Mon Jan 16, 2006 12:13 am    Post subject: Re: Does this process seem feasible? Reply with quote

Thanks for your reply. In fact the alternating current was one of my
concerns. Intuitively, it seems that whatever may deposit on the
electrodes would be oxidized on the positive half cycle and reduced on
the negative half cycle, for a net effect of zero.

Regards,
Joe

Oscar Lanzi III wrote:
Quote:
I don't see anything wrong with it. Don't e scared by the "alternating
current." The cathodic reaction may not be the reverse of the anodic
one.

--OL
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Oscar Lanzi III
science forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 176

PostPosted: Sun Jan 15, 2006 12:05 pm    Post subject: Re: Does this process seem feasible? Reply with quote

I don't see anything wrong with it. Don't e scared by the "alternating
current." The cathodic reaction may not be the reverse of the anodic
one.

--OL
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samwyse@gmail.com
science forum beginner


Joined: 10 Dec 2005
Posts: 6

PostPosted: Sun Dec 11, 2005 3:26 am    Post subject: Re: Building a Voltaic pile Reply with quote

Many thanks to everyone who replied!

Dave wrote:
Quote:
the battery tester is probably meant to read current to tell you how good
the battery is.

Here's the incredibly cheap tester I used: http://tinyurl.com/8djef
-or-
http://www.radioshack.com/product/index.jsp?productId=2103165&cp=2032058.2032235.2032306&parentPage=family

Quote:
also, get rid of the salt, you want acid like vinegar or lemon juice or
dissolved vitamin c tablets. and remember, the towels need to be very wet
so the metals have a good path to drive ions through liquid... but they
shouldn't be so wet that the acid bridges between cells or it essentially
just shorts them out. a better material for the dividers is blotting paper,
but the towels will work if you get them wet enough.

That may be my problem, then. I worried about the foil shorting things
out, but not the paper. Those 1" squares flopped everywhere.

Quote:
just as a quick sanity check, with apple cider vinegar, one penny, and one
square of foil I get .7v at about 2ma. that won't be enough to budge a
battery meter but it registers well on a volt meter.

As an ex-EE, I'm ashamed to say that I haven't seen my voltmeter in
ages. I guess I need to go buy a new one.

Quote:
and remember, the
current is limited by the diameter of the penny and foil, stacking more in
series won't increase the current it can generate only the voltage. you
need more surface area to get more current. or hook them in parallel.

We're working off of a project in a book which claimed that twelve
cells in series would create a visible spark. Oh, well.
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Don Kelly
science forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 166

PostPosted: Sun Dec 11, 2005 2:49 am    Post subject: Re: Building a Voltaic pile Reply with quote

----------------------------
<cornytheclown@hotmail.com> wrote in message
news:1134268135.405323.40630@g49g2000cwa.googlegroups.com...
Quote:
try some pennies and get some galvanized sheet metal...any heating and
cooling outfit can cut you some little squares of sheetmetal. might
even have some copper sheet laying around...or you could get some
copper pipe and cut it down the middle...spread and beat out flat with
hammer and cut some squares.....or you could get some galvanized
washers at the hardware store....
hardware store alsom might have small piece of galvanized metal
strapping they could let you have.

try lemon juice as an acid.....and maybe do some research on sal
ammoniac....I think thats what people used years ago to make homemade
cells......


Put the lemon juice on blotting paper between the pennies and galvanised
washers. This keeps the electrolyte where it belongs.
Alternatively stick a copper wire and a galvanised nail into a lemon.

--

Don Kelly @shawcross.ca
remove the X to answer
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Mike Amling
science forum Guru


Joined: 05 May 2005
Posts: 525

PostPosted: Thu Oct 06, 2005 1:54 am    Post subject: Re: Effect of pH Reply with quote

Quote:
Effect of pH

Click the Mechanism menu to open a Mechanism window, tick the "pH effect"
checkbox, change the number of H+ in the charge reaction, and then click
the
OK button to close the Mechanism window. Click the Kinetics menu to open a
Kinetics window, change the pH value in the Solution section, and then
click
the OK button to close the window. Run the simulation. You should see the
peaks shift when pH is larger or less than 7. As the pH value increases,
the
peak shifts to more negative potential. For a charge reaction

a A + h H+ + ne = b B

where a is the reactant number, b is the product numbers, h is the number
of
H+, and n is the electron number. The relationship of the peak position
with
the pH value usually is linear:

Ep = k1 - k2 pH

Where k1 and k2 are constants. k2 depends on the electron number, the
number
of H+, the numbers of reactant and product, and temperature. For a=b, it
becomes

Ep = k1- RTh/nF pH

For a=b and h=n, it becomes

Ep = k1- 0.059 pH

It shows that both peaks in CV shift to 59 mV more negative potential per
pH. These agree with the theoretical equation (2.5).



www.electrochemist.com
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rekuci@gmail.com
science forum addict


Joined: 22 Sep 2005
Posts: 98

PostPosted: Sat Oct 01, 2005 1:56 pm    Post subject: Re: Looking for more info on Ceraphite "aka white carbon" tia sal Reply with quote

I responded to this yesterday but for some reason the reply got lost.

Science Citation Index gives exactly one result for 'ceraphite', a
meeting abstract by Japanese scientists from Toshiba Ceramic Co
published in the obscure journal Carbon in 1977. The title is
"Ceraphite, a new hard and high-strength carbon material". Looks like
a case of wikipedia syndrome.
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muha
science forum Guru Wannabe


Joined: 08 May 2005
Posts: 167

PostPosted: Fri Sep 30, 2005 4:01 pm    Post subject: Re: Looking for more info on Ceraphite "aka white carbon" tia sal Reply with quote

There is one more form of carbon that can be perfectly white - although
not very soft. Uncle should have kilos of is in jars somewhere - unless
Devil has eaten him for posting in phys.sci too much


sal wrote:
Quote:
Greetings All,

I Had a little dream about white carbon so I decided to look it up and what
I found is
that it's called Ceraphite. The problem is all the websites I've found
using google say the same
thing

"Ceraphite is the fourth allotropic form of carbon, also known as white
carbon.
Discovered in 1969, it is one of the softest substances known to man. It is
formed as small
transparent crystals on the edges of planes of graphite when heated to
above ~2550 kelvins at
low pressures under free-vaporization conditions. It is a transparent
birefringent material. Very little
information is currently available about this allotrope [1]."

Does anybody have anymore information about Ceraphite, the uses it might
have, or where I can get more info?

Thanks
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rekuci@gmail.com
science forum addict


Joined: 22 Sep 2005
Posts: 98

PostPosted: Fri Sep 30, 2005 1:09 pm    Post subject: Re: Looking for more info on Ceraphite "aka white carbon" tia sal Reply with quote

sal wrote:
Quote:
Greetings All,

I Had a little dream about white carbon so I decided to look it up and what
I found is
that it's called Ceraphite. The problem is all the websites I've found
using google say the same
thing

"Ceraphite is the fourth allotropic form of carbon, also known as white
carbon.
Discovered in 1969, it is one of the softest substances known to man. It is
formed as small
transparent crystals on the edges of planes of graphite when heated to
above ~2550 kelvins at
low pressures under free-vaporization conditions. It is a transparent
birefringent material. Very little
information is currently available about this allotrope [1]."

Does anybody have anymore information about Ceraphite, the uses it might
have, or where I can get more info?

Searching the Science Citation Index brings up exactly 1 result for
'ceraphite' from a 1977 meeting abstract in the obscure journal
'Carbon'. The title of the abstract is "Ceraphite, a hard and
high-strength new carbon material". The abstract is cited all of zero
times. Unless it has another common name, sounds like a case of
wikipedia syndrome to me.
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Farooq W
science forum Guru Wannabe


Joined: 25 Mar 2005
Posts: 240

PostPosted: Tue Aug 23, 2005 9:50 am    Post subject: Re: Why the redox titration curve does not start at zero volt? Reply with quote

Borek wrote:
Quote:
On Mon, 22 Aug 2005 18:39:44 +0200, Farooq W <farooq.w@gmail.com> wrote:

Assume that we dip the ORP electrode in a solution that
contains _only _ ferrous ions?

No such animal. If there is water, it can be be reduced or oxidized
(with O2 or H2 evolution):

H2O + e -> OH- + 1/2 H2
H2O -> 2H+ + 1/2 O2 + 2e

You will have some equilibrium between water half reaction and
Fe half reaction. Doesn't matter what kind of Fe ions (II or III)
you put into the solution, always both will be present.

Best,
Borek

Another person explained this observation as follows: Assume we have
_pure_ Fe(II) solution. Whenever we dip a metal in a solution
containing any _other_ metal ions there will still be some finite
potential. Platinum is a metal and you have ferrous ions in the
solution.

This is true experimentally, which I remember doing, i.e. using a iron
nail and aluminum nail, dip them in the same jar containing sodium
chloride solution, connect the external circuit to a galvanometer, and
you see current flowing through the cell.

Conventially, the potentials are introduced using the same metal dipped
in its own ions say, Zn in 1 M Zn(II). If I recall correctly, Nersnt
did say something about metal M dipped in solution of Z ions. He noted
that a potential did develop but that was variable and unpredictable.



Quote:
--
http://www.chembuddy.com - chemical calculators for labs and education
BATE - program for pH calculations
CASC - Concentration and Solution Calculator
pH lectures - guide to hand pH calculation with examples
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Martin Riddle
science forum beginner


Joined: 20 Jul 2005
Posts: 1

PostPosted: Wed Jul 20, 2005 8:18 pm    Post subject: Re: Atmospheric Effect on Dendrite Growth Reply with quote

Eagle Pitcher (the battery company) had some problems with their sealed batteries and dendrite growth when dischaged and left un-used. I recall a topic on wiskers, but I dont know if its the same chemical process.

Cheers

"Bill Janssen" <billj9@ieee.org> wrote in message news:6eaDe.1577$cg.674@news02.roc.ny...
jacques jedwab wrote:

In article <1121760467.786364.301160@o13g2000cwo.googlegroups.com>,
"WAYNEL" <mail@wlawson.com> wrote:

I am trying to calculate if the atmosphere has an affect on the growth
of dendrites, e.g. copper. Eliminating the atmosphere and growing
dendrites in a vacuum may prove to be difficult to run, as the
electrolyte will outgas and thus evaporate.
However, if a test was constructed using Argon or any other inert gas
would one notice an effect?
Consider another test. Rather than using an inert gas, used CO2, could
this effect the growth of a dendrite.
Are there papers on the atmospheric effect on dendrite growths?
Can anyone propose any potential effects the atmosphere may have?
Or is the electrolyte the "dendrite's atmosphere" and this
vehicle may pick up atmospheric contaminates that could produces
various species?


Cheers

WayneL

Most theories of dendrite growth attribute this habit to differential
concentrations of impurities on certain crystal faces, edges, corners,
etc.
But these theories were devised for metal melts.

J.J.
Bell Labs may have published info on dendrites as the telephone companies had trouble
with dendrites in sealed crystal filters. One of the repair practices was to put a "megger" on
selected connections and burn the dendrite clear. I seem to remember Bell Labs publishing
something on the problem. The filter problem (I think) involved Tin. The problems
I remember were in the 1950's time frame.

Bill K7NOM
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Bill Janssen
science forum beginner


Joined: 19 Jul 2005
Posts: 2

PostPosted: Tue Jul 19, 2005 2:53 pm    Post subject: Re: Atmospheric Effect on Dendrite Growth Reply with quote

jacques jedwab wrote:

Quote:
In article <1121760467.786364.301160@o13g2000cwo.googlegroups.com>,
"WAYNEL" <mail@wlawson.com> wrote:



I am trying to calculate if the atmosphere has an affect on the growth
of dendrites, e.g. copper. Eliminating the atmosphere and growing
dendrites in a vacuum may prove to be difficult to run, as the
electrolyte will outgas and thus evaporate.
However, if a test was constructed using Argon or any other inert gas
would one notice an effect?
Consider another test. Rather than using an inert gas, used CO2, could
this effect the growth of a dendrite.
Are there papers on the atmospheric effect on dendrite growths?
Can anyone propose any potential effects the atmosphere may have?
Or is the electrolyte the "dendrite's atmosphere" and this
vehicle may pick up atmospheric contaminates that could produces
various species?


Cheers

WayneL



Most theories of dendrite growth attribute this habit to differential
concentrations of impurities on certain crystal faces, edges, corners,
etc.
But these theories were devised for metal melts.

J.J.


Bell Labs may have published info on dendrites as the telephone

companies had trouble
with dendrites in sealed crystal filters. One of the repair practices
was to put a "megger" on
selected connections and burn the dendrite clear. I seem to remember
Bell Labs publishing
something on the problem. The filter problem (I think) involved Tin. The
problems
I remember were in the 1950's time frame.

Bill K7NOM
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WAYNEL1
science forum beginner


Joined: 04 May 2005
Posts: 25

PostPosted: Wed Jun 22, 2005 8:41 am    Post subject: Re: Conversion of conductivity to molar concentration Reply with quote

These are the same questions I have raised and yes you are right mybe
Pourbaix are not for me. But I could use them as an indicator as a map
of what could happen, is this the best way to use the Pourbaix in my
application - as an indicator?

Thanks
WayneL
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