Give the empirical formula of each of the following compounds if a sample contains c.40.0% C, 6.7% H, and 53.3% O by mass.

Verified step by step guidance

1. Step 1: Assume a 100 g sample of the compound, which means you have 40.0 g of C, 6.7 g of H, and 53.3 g of O.
2. Step 2: Convert the mass of each element to moles by dividing by their respective atomic masses: C (12.01 g/mol), H (1.008 g/mol), and O (16.00 g/mol).
3. Step 3: Calculate the mole ratio of the elements by dividing each element's mole value by the smallest number of moles calculated in Step 2.
4. Step 4: If necessary, multiply the mole ratios by a whole number to get whole numbers for each element.
5. Step 5: Write the empirical formula using the whole number mole ratios as subscripts for each element.

Key Concepts

Empirical Formula

The empirical formula represents the simplest whole-number ratio of the elements in a compound. It is derived from the percentage composition of each element by mass, allowing chemists to understand the basic composition of a substance without detailing the actual number of atoms present.

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 a given sample.

Mole Concept

The mole concept is a fundamental principle in chemistry that relates the mass of a substance to the number of particles it contains. One mole of any substance contains Avogadro's number (approximately 6.022 x 10²³) of entities, allowing for conversions between mass and moles, which is essential for calculating empirical formulas.