Molecular Formula 2

Molecular Formula: The actual formula for a molecule.


A compound is 75.46% carbon, 4.43% hydrogen, and 20.10% oxygen by mass. It has a molecular weight of 318.31 g/mol. What is the molecular formula for this compound?


  1. Find the empirical formula.

  2. Find the mass of the empirical unit.

    10(12.00) + 7(1.008) + 2(16.00) = 159.06 g/mol

  3. Figure out how many empirical units are in a molecular unit.

    (318.31 g/mol) / (159.06 g/mol) = 2.001 empirical units per molecular unit

  4. Write the molecular formula.

    Since there are two empirical units in a molecular unit, the molecular formula is:



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