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Author Topic: How does a radioisotope behave in an electrolyte?  (Read 4677 times)

Offline sorin cezar

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Take a piece of Zr radioisotope metal and dip it into a non radioactive solution of  Zr(NO3)2. Leave it for hours or days …
Then measure the radioactivity of metal plate and the radioactivity of solution.
In my experiments the radioactivity of solution remained unchanged (null to be more precise) and the radioactivity of Zr metal piece changed in time according to already known laws of radioactivity.
All are nice up to this moment but …. Haven’t we forgotten something?
According to electrochemistry, having a metal electrode deeped into a solution that contains ions of that metal, a potential  between the metal and the solution appears according to actual interpretation due to the following equilibrium:
M    =      Mn+   + ne-
Consequently, when the metal strip contain only one (radioisotope) and the solution of its salt contain another isotope, after a period of time there will be a process of isotopic change between metal and solution.
Why there is no exchange between radioisotope and solution?
Of course for the experiment metals behind hydrogen in electrochemical series have to be used. A metal before hydrogen will react with water, and the solution will become radioactive.

I have checked the same situation in case of transitional metals and their solution using stable isotopes. As far ICP MS measurements are a simple task in these days, the same experiment can be performed using stable isotopes. The result is again negative.
In this case what is the cause for the electrode potential if there is no exchange between metal and solution?

« Last Edit: 01/11/2013 22:25:30 by chris »


 

Offline Bored chemist

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Re: Isotopes and electrod potential
« Reply #1 on: 22/10/2013 15:44:15 »
"Why there is no exchange between radioisotope and solution? "
Because Zirconium is covered by a thin layer of the very insoluble oxide.



BTW, who is giving you radioactive materials to play with?

 

Online alancalverd

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Re: Isotopes and electrod potential
« Reply #2 on: 22/10/2013 17:53:51 »
Try using a hydroxide solution. Alkalis often dissolve oxides better than acids.
 

Offline chiralSPO

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Re: Isotopes and electrod potential
« Reply #3 on: 23/10/2013 15:04:05 »
There probably is some exchange, but only at the very surface. At room temperature, mobility of atoms in solid metal is pretty low. It would be detectable if you could measure the changes with much higher precision, or allowed the equilibration to occur over millions of years. The half life of Zr-96 is 2.4e19 years, so this won't be a problem--actually how much radioactive decay did you say you measured?
 

Offline sorin cezar

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Re: Isotopes and electrod potential
« Reply #4 on: 24/10/2013 15:30:45 »
I would like to think we make constructive and realistic comments....

If Zirconium covers with a layer of oxide in this case the electrod potential is zero... which is not the reality...
Zr do not covers with layer of oxide under actual working condition and after actual chemistry concepts.

If we measure an electrod potential and we ,,accept” this electrode potential is given by the equilibrium presented in the main text ... it is only a piece of cake to calculate how much electrons are necessary to build up that potential and how much atoms per second are changed between metal and solution.
So ... again a simple calculation will show that ,,if an elecrode potential appears in few seconds” there should be a ,,correspondent” in the speed of exchange between metal and solution.
When I will wait for months to arrive at an equilibrium potential ....then it is another situation ...
 

Offline Bored chemist

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Re: Isotopes and electrod potential
« Reply #5 on: 24/10/2013 19:34:53 »
"If Zirconium covers with a layer of oxide in this case the electrod potential is zero"
Or you have missed something.

In this case one thing you have missed is this
http://en.wikipedia.org/wiki/Quantum_tunnelling

I invite you to consider which of two things is more likely.
1 You are right and you have found something genuinely new to science or
2 You don't know enough science to understand what you have discovered, but the rest of science understands it just fine.
 

Offline sorin cezar

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Re: Isotopes and electrod potential
« Reply #6 on: 26/10/2013 10:01:40 »
It seems you have got it completely wrong here....

I know the quantum effect ... but you cannot ask for help thinking it will solve the situation.

In quantum tunnell efect an electron travels somewhat through a potential barrier...
Here, if an oxide layer get formed (if!!!), an entire atom has to be pushed through this layer into solution and electrons remains on the metal part and this is completely outrageous.
Maybe it is possible, but even in this case, all manuals and treatise of electrochemistry have to change the explanation.

 

Offline Bored chemist

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Re: Isotopes and electrod potential
« Reply #7 on: 26/10/2013 16:34:57 »
No,
what you have not understood this time is that an oxide layer can have an electrode potential- even thought it is an insulator- because the electrons can tunnel through it so you are simply wrong when you say "If Zirconium covers with a layer of oxide in this case the electrod potential is zero".
And there's no question that it forms such a layer, it can be enhanced by anodising in much the same way as with aluminium.
Since the oxide layer can gain or lose zirconium ions there isn't any need for " an entire atom has to be pushed through this layer into solution"
You just don't understand the mechanism by which the reactions occur.

I really don't think I am the one to " have got it completely wrong here...."
 

Offline sorin cezar

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Re: Isotopes and electrod potential
« Reply #8 on: 28/10/2013 14:44:05 »
An oxide layer has an ,,electrode potential"? What is the mechanism for this electrode potential?
Are you suggesting that chemist are using electrodes with oxides layers and they did not observe that?
I cann accept that a metal cen get a layer of oxide in atmosphere...but a Zr metal in its solution is a ,,exception".
I made the experiment using Cu electrodes and CuSo4 solution and measured the isotopic exchange by ICP MS, and the situation is the same...
I made the same experiment for other tranzitional metals ...
In this case all manuals and treatise of chemistry have to be corrected...
 

Offline SimpleEngineer

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Re: Isotopes and electrod potential
« Reply #9 on: 28/10/2013 16:29:07 »
I thought the actual exchange of atoms was a very simplistic idealogy of oxide plating.. when what happens in fact is the surface becomes your anions whilst the cation remains part of the whole. Orrrr... the radioisotope is not as reactive and is withheld.. (thinking chromium in stainless steel)   
 

Offline chiralSPO

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Re: Isotopes and electrod potential
« Reply #10 on: 28/10/2013 17:02:33 »
I think it is commonly accepted that most metals (even unreactive ones like platinum) form an oxide surface on exposure to air (or in aqueous solutions). Electrochemistry depends on these oxide layers.

Natural copper on earth is about 60:30 split between 63Cu and 65Cu. Unless you have a specially prepared copper electrode or solution (very expensive!), I would imagine both have very similar isotope ratios. If that is the case, it doesn't matter how much the atoms exchange from one to the other, you won't be able to measure a change in isotope ratios for either sample.
 

Offline Bored chemist

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Re: Isotopes and electrod potential
« Reply #11 on: 28/10/2013 20:10:16 »
"I cann accept that a metal cen get a layer of oxide in atmosphere...but a Zr metal in its solution is a ,,exception"."
no it isn't.
Stop ignoring reality.
Zr is coated with a layer of oxide- just like Aluminium.

"An oxide layer has an ,,electrode potential"? What is the mechanism for this electrode potential? "
Yes, learn some electrochemistry.

"In this case all manuals and treatise of chemistry have to be corrected..."
What? they should change the books on the basis of someone who doesn't understand chemistry?
 

Offline sorin cezar

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Re: Isotopes and electrod potential
« Reply #12 on: 29/10/2013 09:54:32 »
The topic does not regards how much of science I understand.
You have said that ,,correct explanation" for electrode potential, at least for some cases is given by Quantum mechanics and formation of a oxide layer on metal surface.

Can you give me at least one reference in a scientific paper or treatise of physics and chemistry which at least remind this possibility?
In case no paper was ever published ... then someone have to do this task ...
 

Offline Bored chemist

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Re: Isotopes and electrod potential
« Reply #13 on: 29/10/2013 19:13:43 »
It doesn't need a paper. Anyone who understands the textbook science involved can work it out.

Since zirconium is always coated with a layer of the very insoluble oxide it is not surprising that no exchange takes place between the bulk metal and a solution of a salt.

That might lead you to wonder how you can get an oxidation potential- unless you realise that the electrons can hop through the thin layer (exactly the same way that they do in many electrical connections BTW)

The ions don't need to travel from the metal to the surface of the oxide- because there are already ions at the surface of the oxide.
Incidentally, having an electrode potential doesn't guarantee that it would be a good material to use in a battery- the oxide layer may slow down the reactions considerably.

Nobody needs to write a paper just to explain something to you.
You need to read some books.
 

Offline sorin cezar

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Re: Isotopes and electrod potential
« Reply #14 on: 31/10/2013 11:12:27 »
I have read more then thousands of books and I assure you that your explanation is not there...
 

Offline Bored chemist

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Re: Isotopes and electrod potential
« Reply #15 on: 31/10/2013 19:06:48 »
OK, perhaps you need to understand some books.
 

Offline sorin cezar

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Re: How does a radioisotope behave in an electrolyte?
« Reply #16 on: 05/11/2013 10:18:19 »
Give me  a reference where such topic is described....
 

Offline Bored chemist

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Re: How does a radioisotope behave in an electrolyte?
« Reply #17 on: 05/11/2013 21:07:48 »
Exactly which bit(s) don't you get?
 

Offline sorin cezar

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Re: How does a radioisotope behave in an electrolyte?
« Reply #18 on: 03/12/2013 08:32:56 »
I asked you to give me a reference where this topic is detailed... and after that based on that reference you will get the breakthrough of proposed experiment ..
 

Offline Bored chemist

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Re: How does a radioisotope behave in an electrolyte?
« Reply #19 on: 03/12/2013 19:47:05 »
Various bits of stuff alluded to in the topic are described in different books.
Which bits don't you understand?
For example, here's the first reference I could find to a surface oxide layer on zirconium
http://bibliothek.fzk.de/zb/berichte/FZKA7373.pdf

Here's a reference to metal/ oxide
electrodes
www.hach.com/asset-get.download.jsa?id=7639984744‎


And so on.
 

Offline SorryDnoodle

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Re: How does a radioisotope behave in an electrolyte?
« Reply #20 on: 13/12/2013 21:25:57 »
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« Last Edit: 14/12/2013 15:53:20 by peppercorn »
 

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Re: How does a radioisotope behave in an electrolyte?
« Reply #20 on: 13/12/2013 21:25:57 »

 

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