Nuclear Chemistry

[YT2095]

I`m quite Fascinated by the idea of this, and since we don`t have a section for it, I figured Here would be the best place.

 

Now, if we look at a decay chain of an isotope you`ll see many daughter products are "born" or decayed into.

 

now from a Chemist standpoint each has their own particular Chemical properties, such as Valency (oxidation states).

 

now supose along this decay chain with start with an Isotope Mono Oxide called XO, along it`s decay chain the Mono oxide cannot exist, it has to be YO2.

 

now imagine there is No free oxygen available and it`s in a sealed environ evacuated.

 

what happens?

do you get half become YO2 and the other half as pure Y?

[swansont]

I think it's more complicated because the typical decay releases far more energy than it takes to disassociate the molecule, so if you start with XO, the decay to Y will send Y moving off, stripping it from the O (especially likely for an alpha decay). And you have the issue of whether the O can migrate and recombine, what happens to the He atom if it was an alpha decay, and whether the Y nucleus can migrate, or replace X in a lattice or if it causes some problems being an interstitial atom. Even for beta decay, I think the daughter gets several eV of KE, which may be enough to break the chemical bond, though it may readily recombine.

 

I know that people do study effects of lattice substitution for various reasons, but am not familiar with studies on decay chains.

[John Cuthber]

I think that the usual problem is (as mentioned above) that the recoil of the atom as it spits out the electron is so big it generally breaks the bonds but I also have a vague recolection that the first synthesis of perbromates was a radiation chemistry type synthesis. Something like 83SeO4 2- --> -83BrO4 - +beta.

The tiny amount of BrO4- was coprecipitated withIO4- and tracked by its radioactive decay.

Can anyone access this page?

http://www.turpion.org/php/paper.phtml?journal_id=rc&paper_id=2526

[YT2095]

new question:

 

watching a documentary the other night and one Rutherfords experiments was to put a piece of Radium inside a gas jar containing air, after some time it was found that a new gas was present in there, Hydrogen.

that the Oxygen in the air was being hit by the radiation and being split into Nitrogen and Hydrogen.

 

is this True?

I always thought you got Helium and Radon if you did that?

 

also, a solution of a Uranium salt was bombarded with Neutrons in the hopes of making an even heavier element, this didn`t happen, instead it converted it into Barium!

apparently though, the reaction of a single one of these transformations gives off enough energy to move a grain of sand! (that`s a massive amount).

so surely the liquid would have gotten Really Hot?

 

anyone?

[swansont]

new question:

 

watching a documentary the other night and one Rutherfords experiments was to put a piece of Radium inside a gas jar containing air, after some time it was found that a new gas was present in there, Hydrogen.

that the Oxygen in the air was being hit by the radiation and being split into Nitrogen and Hydrogen.

 

is this True?

I always thought you got Helium and Radon if you did that?

 

Yes, it is

 

I love these old papers, because with the decades of hindsight the physics is so clear, but was muddled to them, e.g. the nuclear structure in this paper. And they were so focused on figuring out the effect, so all of the steps to eliminate each possible cause other than the conclusion is often very detailed. Also the methodologies that were available to them — Rutherford didn't go out an buy a tank of pure, dry nitrogen, he probably prepared it locally (or had a student do it).

 

also, a solution of a Uranium salt was bombarded with Neutrons in the hopes of making an even heavier element, this didn`t happen, instead it converted it into Barium!

apparently though, the reaction of a single one of these transformations gives off enough energy to move a grain of sand! (that`s a massive amount).

so surely the liquid would have gotten Really Hot?

 

anyone?

 

That would happen in fission, which would release about 200 MeV per reaction, though I don't see that moving a grain of sand. One mention of that as a prediction is here, but it's not clear what energy value they were using (the prediction may have used a larger mass value than is actually converted)

 

It should get hot. You could probably boil water and run a steam turbine with it.

[YT2095]

wow, what a fantastic read, Thanks!

I`ll have a re-read a bit later and take a few notes.

 

so what is it that causes the Radon and Helium then?

I`m guessing that the He is just the Alpha particle that picks up electrons after it`s ejected, and that maybe the Argon in the air gets made heavier somehow to become Radon (both are in group 7).

 

so it seems a neutron source applied to a uranium salt creates heat...

 

so if I made a soln of Uranyl Nitrate, wrapped thorium metal in alu foil and then put that in parafin wax then made a lead shield where the opening was "aimed" at the Uranium soln, I should notice a temperature increase?

[YT2095]

ok, I have a Further Hypothesis...

 

If I were to make Uranium Sulphate (perfectly water soluble), and then put this soln in a vessel with a pointed base to collect any precipitate into one area, and then hit this soln with Neutrons, the Barium created should react instantly to make insoluble barium sulphate!

 

in time I should get a PPT at the bottom of the vessel.

 

 

SECOND:

 

if I used Heavy water instead, the Alpha particles that come from the Uranium should create their Own neutrons and the reaction should be self sustaining (until all the U turns into Ba).

 

now it`s not as elegant and as controllable as having a neutron gun aimed at it, so you probably need some sort of moderator in there or add a little at a time until a workable level is reached and then stay there.

 

 

would/could it work?

 

could I MAKE an Element!

[insane_alien]

well, the 1st one seems fine. the rate will depend on the neutron rate.

 

the second would depend on the amount you have. much like criticality.

 

most of the neutrons would likely escape so i doubt it would be self sustaining but it would mean you wouldn't have to fire as many neutrons into it.

[YT2095]

escaping neutrons is somewhat troublesome, I can`t think of any material or energy barrier that would contain or reflect them either

 

a few mil of Alu and then Lead plate will absorb just fine, but that`s wasting all the goodness really

 

 

non the less, Some reaction should take place over time and I will have made an Element, even if it`s only a few micrograms.

[insane_alien]

you'd still be beating all the alchemists anyway

[John Cuthber]

I don't think "a few mil of Alu and then Lead plate " will get you anywhere at all as a neturon shield.

I've only got tables of thermal neutron capture cross sections but I don't think that will matter much. I wouldn't want to be hiding behind Al or Pb from a neutron source. The capture probabilities are rather small. A thick layer of water to slow them down then a layer of borax to actually capture them then a layer of more shielding to block the energy released by the capture.

 

A microgram of barium is about 1/130 µmol so about 5 *10^15 atoms.

Lets say you get a smoke detector as the neutron source. Something like 1µCi or about 37000 alphas a second. With a really good Am/Be source about 30 alphas in a million will produce a neutron.

So you have about 1 neutron a second.

OK all you need is to set it up and wait for something like 10^15 seconds to get your microgram of Ba (the Ba isn't the only possible product but I'm offsetting that against the neutron multiplication by fission; this is a crass approximation).

See you in 31 million years.

 

Actually, it gets worse than that; BaSO4 isn't very soluble but it does dissolve a bit. My trusty cop of the CRC book gives the solubility as 222µg/ 100 mls.

To be sure of getting the neutrons thermalised you need to send them through a foot or so of water so I can't see you setting this up with less than a liter or so of water (actually, since you would need the source surrounded by water you would need something like a 2 foot dianmeter spherical flask of solution. That's tens of litres.

Well, if 222µg of BaSO4 dissolve in 100 ml than that's 22200 µg disolve in 10 litres.

 

See you in six hundred billion years.

[YT2095]

I have a 15 gallon fish tank, don`t worry about the water, and don`t worry about the neutron source, although I have to ask why you think a fire alarm Am241 slug would do the job?????

in that case you would more than likely be correct, but that`s Not what I`m thinking I assure you!

thus far you`ve told me Nothing I don`t already know or have calculated.

and yes the Alu 1`st and the 3cm lead will be plenty to block! the borax is neat though, I may employ that also.

 

oh, and you didn`t address my Heavy water usage either, how do you expect that to perform?

 

Anyone?

[John Cuthber]

" have to ask why you think a fire alarm Am241 slug would do the job?????"

I didn't in fact I thought I made it preetty cleare that it wouldn't do the job. On the other hand I think it's about as potent a source as most people have access to.

If you can get hold of a source a million times better then you only need to wait a million years or so.

Heavy water is actually a less effective moderator than ordinary water, It gets used because its capture cross section is smaller. You would need more of it so the problem gets even worse because more water means more BaSO4 would dissolve and so you would need more to precipitate it.

 

Essentially you are trying to build a nuclear rector. I don't think most governments are up to that never mind individuals.

 

Also, re neutron screening.

http://hps.org/publicinformation/ate/q1094.html

4th paragraph of the answer.

 

I don't see why you think Al has some magic property of blocking neutrons. Al alloys are used as fuel cans in reactors. How well would they work if the neutrons never got anywhere?

It has a capture cross section of about a quarter of a barn. Steel would do a better job.

[YT2095]

did you read this bit:

 

"For this reason it happens that materials that have low-mass nuclei are good for shielding the neutrons because the neutrons can transfer large amounts of their energy to the light nuclei through collisions (referred to as elastic collisions)."

 

and so Alu ( a cheap and readily available material) is ideally suited, and then a Lead plate surround... I don`t see the problem?

 

I think you need to read ALL the thread too, I`m addressing the OP also in my questions, I expect Heat energy also.

 

yes, I Am thinking of a "one pot" reactor for wants of a better word(ing).

 

and no I don`t think it`s impossible at all, in fact I think it`s quite Likely to work very well, even if the Barium side isn`t so great an idea.

 

the idea is this, a Juncture between Chem and Nuclear stuff, but rather than have This ray hit That target, if you have a homogenous mix of all the required parts, something HAS TO happen!

 

think, there are more atoms in a glass of water than there are glasses of water in all the oceans and lakes on the entire planet!

now, make a solution of these parts an probability dictates that you will get LOTS of reactions happen constantly.

 

sure plenty will fail, but if a single Uranium to Barium reaction has the power to move a grain of sand, then thousands of these at the same time Should make heat!

[John Cuthber]

They use hydrogen as a neutron moderator because it has the same mass as the neutron. The deutierum that alos gets used (because of a poor capture crosssection) while it is only wtice the mass of the neutron does a noticably poorer job. Aluminium is a lot heavier and will barely reduce the momentum of the neutron at all.

Al simply isn't a light nucleus so it doesn't work very well, so yes, I read that bit of the article and I know what it means.

Since it takes somthing like a foot of water to thermalise neutrons, surely you can see that a few mm of something that's a poor moderator is a non-starter.

The lead is, of course, heavier still and therfore even less use.

 

I'd still like to know why you think they can nuclear fuel elements in Al if you think it will block the neutrons.

 

On the subject of the OP; where's the chemistry?

A homogeneous reactor is possible; they happen from time to time by accident but you need a lot of enriched highly fissionable material to do it.

 

http://www.uic.com.au/nip52.htm

 

but if a single Uranium to Barium reaction has the power to move a grain of sand, then thousands of these at the same time Should make heat!

 

Each fission event releases about 200MEV i.e. about 3.2*10^-11J

A thousand of them a second would generate thirty two whole nanowatts.

What do you plan to do with that?

A reactor will generate heat, if you can get one to work. Many countries don't have the resources to do that, so I don't see you doing it any time soon. Possibly just as well if you plan to sheild it with Aluminium.

[YT2095]

Rutherford did it in Manchester Uni.

 

using a Radium source, alu (or maybe Be I forget) and Parafin wax as the neutron source.

 

a Uranium salt soln was exposed to this and Barium was discovered to be formed from it.

 

my idea is that if it`s Uranium Sulphate then this should show quite easily in a small pointed base vessel.

 

the Boric acid (as mentioned above) was agreed upon wasn`t it?

 

I want to know if it will work, we`ve already strayed far from my questions, lets not spam it with other trivialities Please!

[John Cuthber]

Rutherford was able to get hold of radioactive sources tat would be practically banned today.

Also, he didn't prepare enough barium to make a precipitate. He irradiated some uranium and got a tiny quantity of baruin (among lots of other things). The then added ordinary barium nitrate then a sulphate to precipitate nearly all the barium in the solution (of course some would have stayed in solution.)

The clever bit is that the barium he produced this way was a mixture of isotopes, some of them were radioactive. So the BaSO4 he precipitated was radioactive.

Because the radioactivity from traces of radioisotopes of barium is easy to detect he didn't need to get all that much radioactive Ba in order to prove that it existed.

All he needed to do was get a chemist (Soddy I think) to separate the radioactivity from any other possible elements in the periodic table and show that it was still radioactive.

He got barium, but never anything like enough to see a ppt.

[YT2095]

Hmmm... Interesting, Thanks.

 

also I found this: http://en.wikipedia.org/wiki/Aqueous_Homogeneous_Reactor

[John Cuthber]

Interesting article (wiki's often are). It also shows that unless you can get hold of exotic isotopes you are not going to get anything happening in something small.