Lesson 7.5: Empirical vs. Molecular Formulas Summary

Key Concepts: Empirical vs Molecular Formulas

Core Definitions

  • Empirical Formula: The simplest whole-number ratio of atoms in a compound (e.g., CH₂O).
  • Molecular Formula: The actual number of atoms of each element in a molecule (e.g., C₆H₁₂O₆).
  • Finding Empirical Formula: Convert percentages to grams → to moles → divide by smallest mole value → round to whole numbers.
  • Relationship: Molecular formula = n × empirical formula, where n = molar mass / empirical mass.
  • Percent Composition: The percentage by mass of each element in a compound.
  • Example: Glucose: empirical = CH₂O (30 g/mol), molecular = C₆H₁₂O₆ (180 g/mol), n = 6.
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