1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook