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Homework Help: Finding atomic mass

  1. Sep 8, 2010 #1
    1. The problem statement, all variables and given/known data
    Naturally occurring iodine has an atomic mass of 126.9045. A 12.3849-g sample of iodine is accidentally contaminated with 1.00070 g of ,129I a synthetic radioisotope of iodine used in the treatment of certain diseases of the thyroid gland. The mass of129I is 128.9050 . Find the apparent "atomic mass" of the contaminated iodine.
  2. jcsd
  3. Sep 9, 2010 #2


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    Staff: Mentor

    How do you calculate atomic mass knowing isotopic composition? Do you know what 'weighted average' is?
    Last edited by a moderator: Aug 13, 2013
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