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Molar Mass calculation

  1. May 16, 2009 #1
    1. The problem statement, all variables and given/known data
    I'm having a lot of trouble trying to find the molar mass of (HOCH2CHOH)CH2O2

    2. Relevant equations

    3. The attempt at a solution
    Do i have to multiply the molar mass inside the bracket (HOCH2CHOH) by the outside CH2O2?
  2. jcsd
  3. May 16, 2009 #2


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    You are asking about how to find the mass of one mole of the compound. Maybe you have some difficulty with the text-based way to express the compound? What is the exact name of your compound? Maybe an empirical formula would make the method more apparant to you.
  4. May 16, 2009 #3
    The compound's name is glycerol
  5. May 16, 2009 #4


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    Thanks. This makes the identity of the compound plain. Now, does the name tell you anything about the structure? Maybe not. Another name for glycerol is 1,2,3-propanetriol. If you know enough about simple naming of organic compounds, you could make sense of that; but since you asked, you did not yet progress that far.

    A good wikipedia article showing the structure is this:
    A molecular formula is also given.
  6. May 17, 2009 #5


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    No. Content of parentheses is to be taken as many times, as number after the closing parenthese tells. No number - no multiplication.

    Ca3(PO4)2 - means 3 atoms of Ca and 2 groups of 1 atom of P and 4 atoms of O.

    Sometimes you may want to use parentheses to show that some group of atoms is to be treated separately for some reason, but this is not a formal notation.

    (Na)Cl - 1 atom of Na, 1 atom of Cl. Parentheses not necesary.

    In this case looks like they put the parenthese only to trick you into thinking there is more to it. There is no.
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