Determine the empirical formulas of the compounds with the following compositions by mass: (a) 74.0% C, 8.7% H, and 17.3% N

Verified step by step guidance

1. insert step 1> Convert the percentage of each element to grams, assuming you have 100 grams of the compound. This means you have 74.0 grams of C, 8.7 grams of H, and 17.3 grams of N.
2. insert step 2> Convert the mass of each element to moles by dividing by their respective molar masses: C (12.01 g/mol), H (1.008 g/mol), and N (14.01 g/mol).
3. insert step 3> Determine the mole ratio of the elements by dividing each element's mole value by the smallest number of moles calculated in the previous step.
4. insert step 4> If necessary, multiply the ratios by a whole number to get whole numbers for each element in the empirical formula.
5. insert step 5> Write the empirical formula using the whole number ratios as subscripts for each element.

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 into moles and then simplified to the smallest integer ratio. This formula provides essential information about the composition of the compound without indicating the actual number of atoms in a molecule.

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.). Understanding the mole concept is crucial for converting mass percentages into moles, which is necessary for determining the empirical formula from the given mass composition.

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 by the total mass of the compound and multiplying by 100. This concept is essential for analyzing the composition of a compound and serves as the starting point for calculating the empirical formula based on the provided mass percentages.