Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Make lead form bismuth

  1. Apr 27, 2007 #1
    could anyone tell such a method how one can make stable lead from stable bismuth?
  2. jcsd
  3. Apr 27, 2007 #2


    User Avatar
    Science Advisor

    Recently it has been discovered that bismuth is slghtly radioactive - i.e. has an extremely long half life.
  4. Apr 29, 2007 #3
    Isn't everything slightly radioactive?

    Anyway, good idea this bismuth, it'll come in handy when all the lead has been converted to gold. :smile:
  5. Apr 29, 2007 #4
    No, pure stable isotopes are not. If you extract hydrogen from Evian mineral water, it is no more radioactive. The time it takes the water to percolate through the Alpes mountains to the source (23 years, I think) is long enough for all traces of tritium to have disappeared. (I have no shares of this company).

    But I think that the question posted was something as "If you bombard bismuth with protons, will it transform in lead?". I do not know the aswer.
  6. Apr 29, 2007 #5
    I doubt that. In the context of exponential decay, "all traces" sounds too strong. Nonetheless, I wasn't originally referring to mixtures of isotopes. Even the proton itself is thought to have a half-life, though the decay hasn't ever been observed yet. If you wait long enough, isn't it a quantum certainty that lead will start changing to iron?

    It might initially be short one neutron, but again surely the answer is eventually yes, provided the yield doesn't need to be high.
  7. Apr 29, 2007 #6
    Holy expletives, Batman! For real? Are you telling me there are no truly stable isotopes, just half-lives so long we don't know what they are? Is the weak force really that badass?

  8. Apr 30, 2007 #7
    Is something radioactive when you can't detect any radioactivity?
    Is the Shrödinger cat death or alive?
    Is this a philosophy forum?
  9. Apr 30, 2007 #8
    I admit, responding to mathman, I've taken this thread entirely off-topic. But you are making this philosophical. Just because *you* don't have a sensitive enough detector to distinguish two things does not mean those things are equal.
  10. Apr 30, 2007 #9


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The problem with this definition of radioactivity is then that it depends on the experimental technique to verify it. This would mean, for instance, that before the 19th century, there were no radioactive materials (as one couldn't detect it at that time, or recognize it as such).

    Now, as pointed out, the proton itself might be "radioactive" (although this was an SU(5) prediction, and falsified by experiment, in that no proton decay has ever been observed, and that this puts the half life well beyond something like 10^35 years or so http://en.wikipedia.org/wiki/Proton_decay ).

    So, at your likings, you could define radioactivity as having a half life below a certain, arbitrarily choosen, value, say, the life time of the universe or something.
  11. May 1, 2007 #10
    If I do not detect something, the only thing that I can say is that I have not detected it and say that if the something exists, its magnitude o probability is less than the sensitivity of my system. But I cannot say "well, I don't see a thing, but it exist".

    People of 19th century could not say that there where or there where not radioactive materials. If a theory of radioactivity had been proposed, the only thing that could be asserted at the time is that no radioactivity had been detected yet.

    It is the same situation today. What can you say about gravity waves? The only thing you know is that, for now, they have not been detected. It doesn't mean that they do not exist. It just means that we don't know and we can't assert either that they exist or the contrary.

    Same thing for the proton mean life and for the Shrödinger's cat. You can't say that the cat is death or alive before opening the box.
  12. May 1, 2007 #11
    Earlier you mistakenly asserted the contrary. :wink:

    Moreover, sometimes a theory is so well tested that we can have good reason to believe even those predictions that we are not yet able to test. (This is quantified using the science of Bayesian plausibility.)

    The well tested theory of decay says that if there was a known ratio of hydrogen and tritium, in water left some finite time ago, then we will find some tritium is still remaining, if we inspect a large enough volume now. Even ignoring whether anyone might yet have determined a half-life for the "stable" isotope of oxygen, it's not accurate to claim such water is completely nonradioactive. Realising the mundaneness of nuclear decay is important if there is to be informed (rather than purely emotional) debate over nuclear power (a major issue that is currently re-entering the public spotlight).
    Last edited: May 1, 2007
  13. May 1, 2007 #12
    How do you know (not bet) that an isotope is stable or radioactive?
    Do you think that the nuclides table is the result of theoretical calculus?
    No, it is the result of measures. As the sensibility of measuring techniques increase, it is possible that isotopes that today are considered stable, will be classified as long half life radioactive. But for now, as no disintegration has been detected, they rest stable.

    You could have done the predictions and the bayesian plausibility for Newton laws for speeds bigger than c before Michelson and Morley experiment.
    Believing in not proved facts, is just a matter of faith, as are the others religions.

    For the Evian water, I did not invent the method. It is nuclear physicists (I'm not) which used it a source of very low (I concede) tritium content water. For practical purposes it is tritium free. Physics is not mathematics, nor mathematical methods. Physics if for the world in which we live.
  14. May 2, 2007 #13
    All this is nice, but there arent any suggestion to my original problem. Someone please:rolleyes:
  15. May 2, 2007 #14
    I thought that you had already understood that we have no answer to your question.

    I think it is difficult. You must take a neutron and a proton from a nucleus!

    Anyway it seems that, as has been said, Bi-209 is not really stable. From:
    http://atom.kaeri.re.kr/ton/ :
    Bi-209 has been known as stable nuclide. But, alpha decay of Bi-209 with a half time of 2*1019 years was found, recently
  16. May 2, 2007 #15
    To expand on what I wrote above:

    Yes, you should be able to do it very simply: by hitting a bismuth target with a proton beam (accelerated hydrogen ions). Some (probably incredibly small) fraction of bismuth atoms should absorb two protons in succession, then beta decay (changing one proton to a neutron), transforming into your desired lead atom.

    However, this is obviously a very costly process, and produces only the tinyest amount of lead. I can't think of any reason you'd try to do it. Similarly, alchemists never made any great profit from their attempts to transmute lead into gold, despite that it is equally possible to do in principle. As a rule, the vast amounts of energy, that you need to cause the reaction, will cost vastly more money than if you just throw away your initial material and bought (say, from a mine) whatever product you actually want. There may be a few exceptions (some isotopes will naturally transmute to something else very quickly, and others, like in uranium power stations, can profitably be made to transmute much sooner than they would naturally), but think of those as "the exception that proves the rule", so no you shouldn't expect to "produce" lead yourself from other elements.
  17. May 3, 2007 #16
    I think that you wrote this without having a look at the periodic table. It is the other way. You must take out a proton and a neutron to transform bismuth to lead.
  18. May 3, 2007 #17
    Ah, good point, you'd think I'm dyslexic! :biggrin: Ok, insert an alpha decay in there somewhere (probably just before the beta decay is most likely).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook