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Homework Help: Help with carbon dating question please

  1. Jul 21, 2011 #1
    desperately need help with the question below. me and my dad have been working on it for hours but keep getting the answer to be 5.97x10^-23???!!!! totally off what it should be.

    Q. There are about 1.3x10^-12 carbon-14 atoms for each atom of carbon-12 in living materials, and the half-life of carbon-14 is 5730 years. Show that the number of disintegrations occuring in 1 mole of carbon from a living organism is 2.3 per second.

    Thanks

    Charley
     
  2. jcsd
  3. Jul 21, 2011 #2

    ehild

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    Show what you and your dad have done so far. What do you know about radioactive decay? What is half-life?

    ehild
     
  4. Jul 21, 2011 #3
    this is what we worked out.....

    (1.3x10^-12) x 12 = 1.56x10^-11 gm C14/gm C

    then using the equation Kb=ln2/half-life...

    Kb=ln2/(1.80x10^11) seconds = 3.85x10^-12 disintegrations per second

    Then....
    (3.85x10^-12) x (1.56x10^-11) = 5.97x10^-23

    what have we missed????
     
  5. Jul 21, 2011 #4

    SteamKing

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    How many atoms are in one mole of a substance? Remember, it is the number of disintegrations of individual atoms that you are looking for.
     
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