Molecular formula — Science definition
Actual atom counts in a molecule.
Where it is taught
- Percent Composition, Empirical & Molecular Formulas — Reactions, Moles & Composition, Physical Science: Chemistry, Grade 11
In use
A molecular formula gives the actual atom count in a molecule.
Percent Composition, Empirical & Molecular Formulas
Questions using molecular formula
Problem 1
An empirical formula is CH₂O, mass 30 g/mol; measured molar mass is 90 g/mol. Find molecular formula. Show the reasoning, not just the conclusion.
Hints
Percentages describe mass, so convert to moles before atom ratios.
Answer and explanation
90/30=3; multiply subscripts to get C₃H₆O₃.