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Homework Help: AMU Too many variables ?

  1. Feb 5, 2008 #1
    AMU Too many variables......?

    1. The problem statement, all variables and given/known data

    the atomic mass of lithium6 is 6.0151 and the amu of lithium-7 is 7.0160. calculate the natural abuncance of hese two isotopes. use the value of 6.941 amu as the value fr the average atomic mass of lithium

    2. Relevant equations

    ave atomic weight = (% of isotope 1)(amu of isotope 1)+(% of isotope 2)*(amu of isotope 2)

    3. The attempt at a solution

    Okay.. So the equation I set up ends up being

    6.941 amu =X(7.0160)+Y(6.0151)

    I have 2 variables, so here I get stuck.... I have no idea how to solve when I have 2 variables.....
  2. jcsd
  3. Feb 6, 2008 #2
    You need a second equation. X and Y are not independent. What is their sum?
  4. Feb 6, 2008 #3
    This link should help.
    http://dbhs.wvusd.k12.ca.us/webdocs/Mole/AvgAtomicWt-Reverse.html [Broken]
    Last edited by a moderator: May 3, 2017
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