Which step would help a student find the molecular formula of a compound from the empirical formula?

• A. Balance the chemical equation for the compound.
• B. Determine the molar mass of the compound and compare it to the mass of the empirical formula.
• C. Measure the melting point of the compound.
• D. Calculate the percent composition of each element in the compound.

Answer: (B)

Verified step by step guidance

1. Understand that the empirical formula represents the simplest whole-number ratio of atoms in a compound, but the molecular formula shows the actual number of atoms of each element in a molecule.
2. Calculate the molar mass of the empirical formula by summing the atomic masses of all atoms in the empirical formula.
3. Determine the molar mass of the compound experimentally or from given data.
4. Divide the molar mass of the compound by the molar mass of the empirical formula to find a multiplication factor (usually a whole number).
5. Multiply all subscripts in the empirical formula by this factor to obtain the molecular formula.