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Homework Help: Small Aluminum Spheres

  1. Jun 5, 2012 #1
    Two small aluminum spheres, each of mass 0.0250 kilograms, are separated by 80.0 centimeters.

    How many electrons does each sphere contain? (The atomic mass of aluminum is 26.982 grams per mole, and its atomic number is 13.)

    The attempt at a solution
    I said that there are 6.02*10^23 atoms in a mole, and noted that after converting the mass into grams each sphere has .9265 moles. If the Aluminum spheres are uncharged there are 13 electrons per atom. I multiplied all three together to get 7.25*10^24 total electrons, but this comes up as the wrong answer.

    Any guidance as to what i'm doing wrong will be highly appreciated, thanks
  2. jcsd
  3. Jun 5, 2012 #2
    What's the right answer?
  4. Jun 5, 2012 #3
    It was on a mastering physics quiz, viewing the right answer was blocked.
  5. Jun 5, 2012 #4
    So, how are you supposed to enter your answer?
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