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Atoms to Formula Units

  1. Apr 6, 2013 #1
    1. The problem statement, all variables and given/known data
    A sample of aluminum oxide, Al2O3(s), contains 8.29*10^25 total atoms. Calculate the amount in moles of aluminum oxide in the sample. Hint: This is a two-step problem. Calculate the number of formula units first.

    2. Relevant equations

    N=N × N[itex]_{A}[/itex]

    3. The attempt at a solution
    8.29×10[itex]^{25}[/itex] ( 1 atm/ 6.02 × 10[itex]^{23}[/itex])
    =1.38× 10 [itex]^{2}[/itex]

    The question mention that it has two steps but I do not know how..
    The correct answer is 27.5 mol ...
  2. jcsd
  3. Apr 6, 2013 #2


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    One molecule of aluminum oxide has 2 Al atoms and 3 O atoms. The sample contains 8.29*10^25 atoms, which includes both Al and O. This sample also represents X moles of aluminum oxide. Hint: figure out the proportions of Al and O in aluminum oxide.
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