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Homework Help: What is the empirical formula of this compound help?

  1. Mar 21, 2008 #1
    A hydrated substance was found to have the following percentage composition= Na 18.53%
    S= 25.87%
    O= 10.34%
    H2O= 62.9%
    What is the empirical formula of this compound?

    what i got was Na2S2O3 - 5H2O
    but im confused cause Na and S are both 0.806 mols
  2. jcsd
  3. Mar 22, 2008 #2
    Perhaps, if you showed your work you might get more answers.
  4. Mar 23, 2008 #3
    10.34/16 < 18.53/23 and 25.87/32, but you have more O atoms in your formula than Na and S. How is that? I got Na5S5O4*22H2O, but thats probably not right.
  5. Mar 23, 2008 #4
    umm hmm i assumed 100 grams and then converted to mols
  6. Mar 23, 2008 #5
    Use this cool poem.

    Percent to mass
    Mass to mole
    Divide by small
    Multiply 'til whole
    Poem by "Joel S. Thompson"
  7. Mar 23, 2008 #6
    That's pretty neat! I'll have to remember that.
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