Molecular Formulas

• if you know an empirical formula to find molecular formula you need the molar mass

Example:

• The empirical formula for a substance is CH2O and its molar mass is 60.0 g / mol. Determine the molecular formula.
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  Empirical Formula	Molecular Formula
  CH2O	C2H4O2
  30.0 g / mol	60.0 g / mol

  
  

Example:

• The empirical formula for a compound is C2H6O and the molar mass is 138 g / mol. Determine the molecular formula.
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  Empirical Formula	Molecular Formula
  C2H6O	C6H18O3
  46 g / mol	138 g / mol

  
  
   
  -Eva