What are the empirical formulas of each of the following substances? (a) Ibuprofen, a headache remedy: 75.69% C, 15.51% O, 8.80% H

Verified step by step guidance

1. Convert the percentage of each element to grams, assuming you have 100 grams of the substance. This means you have 75.69 grams of C, 15.51 grams of O, and 8.80 grams of H.
2. Convert the mass of each element to moles by dividing by their respective molar masses: C (12.01 g/mol), O (16.00 g/mol), and H (1.01 g/mol).
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. If necessary, multiply the mole ratios by a whole number to get whole numbers for each element in the formula.
5. Write the empirical formula using the whole number mole 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 percentage composition of each element, allowing chemists to understand the basic composition without detailing the molecular structure.

Percentage Composition

Percentage composition refers to the mass percentage 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 information is crucial for determining the empirical formula from the given data.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between grams and moles, which is necessary when calculating the empirical formula from the percentage composition of elements in a compound.