Determine the empirical formulas of the compounds with the following compositions by mass: (b) 57.5% Na, 40.0% O, and 2.5% H

Key Concepts

Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present in that compound. It is derived from the mass percentages of each element, which are converted to moles and then simplified to the lowest ratio. This formula does not provide information about the actual number of atoms in a molecule but rather the relative proportions of each element.

Mole Concept

The mole is a fundamental unit in chemistry that quantifies the amount of substance. One mole corresponds to Avogadro's number, approximately 6.022 x 10²³ entities (atoms, molecules, etc.). To determine the empirical formula, the mass percentages of elements are converted to moles by dividing by their respective atomic masses, allowing for the comparison of the number of moles of each element.

Mass Percent Composition

Mass percent composition refers to the percentage by mass of each element in a compound. It is calculated by dividing the mass of each element in a sample by the total mass of the sample and multiplying by 100. This information is crucial for determining the empirical formula, as it provides the starting point for converting mass to moles and establishing the ratios of the elements.