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Homework Help: Conversion of moles

  1. Nov 30, 2007 #1
    1. The problem statement, all variables and given/known data

    Find the rms speed for an argon atom if 9.0 mol of the gas is confined to a 8.2 liter container at a pressure of 5.4 atm.

    *I know how to solve the problem, but I forget how to convert 9.0 moles of Argon into moles/kg..how do you do that??

    2. Relevant equations

    mass# of Ar= 39.9
    Av. constant 6.02x10^23
    1000g=1 kg

    3. The attempt at a solution

    I think I need to divde 39.9 grams of argon by 1000 to convert it to kg and then do I divde by 9 moles?
  2. jcsd
  3. Nov 30, 2007 #2
    For the conversion you require, you need to know the atomic mass of Argon from the periodic table. Given this, the answer comes directly from the definition of the mole.

    Edit: sorry, just realised you already have the atomic mass. In that case, you know that 1mol has mass 39.9g as you say.
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