Practice Molecular Formula in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

The chemical formula showing the actual number of atoms of each element in one molecule of a compound, as opposed to the empirical formula which.

The real count of atoms, not just the ratio — it tells you exactly what the molecule contains.

easy

Explain the difference between an empirical formula and a molecular formula. Give an example where they differ.

medium

A compound has an empirical formula of

\text{NO}_2

and a molar mass of

92\,\text{g/mol}

. Determine the molecular formula. (N =

14.01

, O =

16.00

)

medium

A compound is 40% C, 6.7% H, 53.3% O by mass. Its molar mass is 180 g/mol. Find the molecular formula.

medium

A compound has empirical formula

\text{CH}

and molar mass

78\,\text{g/mol}

. Find the molecular formula. (C =

12.01

, H =

1.008

)

hard

A compound is

85.7\%

C and

14.3\%

H by mass, with a molar mass of

56.0\,\text{g/mol}

. Determine both the empirical and molecular formulas.