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Homework Help: Chem Mole: Molecules to Atoms?

  1. Oct 25, 2008 #1
    1. The problem statement, all variables and given/known data
    What is the total number of atoms in the molecules?
    NH3 - 2.5 mole

    2. Relevant equations
    Would you multiply the number of atoms in NH3 by Avogadro constant to find the number of atoms?
    (4 atoms)(6.02*10^23)

    Or would you multiply the number of moles by Avogadro constant, and then multiply that by the number of atoms?
    (2.5 moles)(6.02*10^23)
    =x- number of molecules in 2.5mole of NH3

    (x)(4 atoms)
  2. jcsd
  3. Oct 25, 2008 #2


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    Almost. Set Up the calculation according to your known units. 1 mole of ammonia is composed of 4 atoms. You have how many moles of given ammonia?

    2.5 moles ammonia * (4 moles of atoms per mole of ammonia) * (AvogNumber..... I will not finish this, but you should try to finish it.
  4. Oct 25, 2008 #3
    Excellent, thank you.

    Just to simplify things, as a skeleton formula, it would look like:

    Total atoms = (total moles)(number of atoms in formula)(Avg con)

    In the case of the original question:
    Total atoms=(2.5)(4)(6.02x10^23)
    Total atoms= 6.02x10^24
  5. Oct 25, 2008 #4


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  6. Oct 25, 2008 #5
    Thanks. :) I finished off the rest of my questions without a hitch.
  7. Oct 26, 2008 #6


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    I made an error in post #2, saying:
    One mole of ammonia molecules contains FOUR moles of ATOMS.
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