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Homework Help: Avogadro/no of molecules

  1. Jun 10, 2009 #1
    1. The problem statement, all variables and given/known data
    A glass of water has a volume of 6.0 x 10*-4 cubic metres.
    How many moles of water molecules are there in the glass?

    2. Relevant equations

    3. The attempt at a solution
    I know it has something to do with Avogadro’s number but can’t figure out exactly what to do.

    The weight of the water molecules will equal 6.0 x 10*-4 kg, right?
    The molecular mass of water molecule is 18.0153 u.

    So would it be 0.0006 kg divided by 18.0153u to give the nuber of moles?
    Then with the number of moles, multiply by avogadros number to get the number of molecules?

    Which gives me 2 x 10*19 molecules?

    Any correction or verification greatly appreciated:smile:
  2. jcsd
  3. Jun 10, 2009 #2
    Hey there chawkdee :smile: Cubic meters are not a unit of weight are they? They are a unit of volume.

    How can you relate the volume of water to its mass?
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