Empirical formula is the simplest formula of a compound showing the ratio of the number of atoms of different elements.

• A. The actual numbers of atoms in a molecule
• B. The charge balance of ions in a compound
• C. The simplest formula showing the ratio of atoms
• D. The mass of a compound

Answer: (C)

Empirical formula describes the simplest whole-number ratio of atoms in a substance. It is not the actual numbers of atoms in a single molecule—that’s the molecular formula—nor is it about the charge balance of ions or the mass of the compound. You get the empirical formula from experimental data (like percent composition) by converting to moles, dividing by the smallest number of moles, and multiplying to obtain whole numbers. This gives the smallest unit that represents the ratios of elements in the compound. For example, a substance that has the ratio of carbon to hydrogen to oxygen as 1:2:1 has an empirical formula CH2O, even if its molecular formula might be C6H12O6.