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Homework Help: Stoichiometry homework help

  1. Feb 22, 2007 #1
    1. The problem statement, all variables and given/known data

    Given the balanced equation 2Al(NO3)3 + 3Mg ==> 3Mg(NO3)2 + 2Al , if 54.1 g of aluminum nitrate is reacted, what mass of magnesium nitrate is produced?

    2. The attempt at a solution
    I've been given an entire packet dedicated to stoichiometry, but nothing in here covers this problem. I am unsure of how to even begin solving it. Maybe if I had help with the first few steps I could solve the rest.
    Last edited: Feb 22, 2007
  2. jcsd
  3. Feb 22, 2007 #2
    a good way to go about this problem is to convert the mass of aluminum nitrate into moles of aluminum nitrate, then you can figure out how many moles of magnesium (do you mean aluminum or magnesium nitrate) were produced.
  4. Feb 22, 2007 #3
    Ok so I converted the grams of aluminum nitrate into moles and got approx. 0.2539 moles. I'm still confused about what to do next, though.
    Last edited: Feb 22, 2007
  5. Feb 22, 2007 #4
    Now you need to use the mole fraction, which you get from the balanced reaction.
  6. Feb 22, 2007 #5
    What is the mole fraction? Like, 2 moles of aluminum nitrate to 3 moles of magnesium nitrate?
  7. Feb 22, 2007 #6
    (2mol Al nitrate/3mol Mg nitrate)
  8. Feb 22, 2007 #7
    Ok, so how do I use this ratio in relation to the 0.2539 moles of aluminum nitrate? I guess I still don't really get all of the steps.
  9. Feb 22, 2007 #8
    It is a dimensional analysis setup

    mol Al nitrate(mole fraction)(convert mol Mg nitrate to g)=soln
  10. Feb 22, 2007 #9
    So I take 0.2539 and multiply it by 2/3 first, right?
  11. Feb 22, 2007 #10
    Never mind, I got the right answer. Thanks for the help. :)
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