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Homework Help: CHEM - Uranium isotope relative abundance at diff times

  1. Feb 28, 2009 #1
    1. The problem statement, all variables and given/known data

    The relative abundance of uranium isotopes in today’s earth crustal material is:
    99.2745% 238U
    0.7196% 235U
    0.0055% 234U
    What were the relative abundances when the earth was formed 4.6x109 years ago?

    2. Relevant equations

    t = age = 1/lambda * ln(N/No)

    N = No*e^lambda*t

    3. The attempt at a solution

    i dont know how to approch this...
  2. jcsd
  3. Mar 1, 2009 #2

    I agree with LowlyPion in the other post that you need to know the half-lives and then I think it will be a matter of ratios.

    Just post a question the once for the future. This is so people helping you are seeing what everyone is saying and not repeating work that has already been done. We only want to help. :biggrin:

    The Bob
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