Determine the empirical formula of each of the following compounds if a sample contains (b) 12.0 g calcium and 2.8 g nitrogen

Verified step by step guidance

1. Calculate the number of moles of calcium (Ca) by dividing the mass of calcium by its molar mass (40.08 g/mol).
2. Calculate the number of moles of nitrogen (N) by dividing the mass of nitrogen by its molar mass (14.01 g/mol).
3. Determine the simplest whole number ratio of moles of calcium to moles of nitrogen by dividing each by the smallest number of moles calculated.
4. Use the whole number ratio to write the empirical formula, with calcium and nitrogen subscripts corresponding to the ratio.
5. Verify the empirical formula by ensuring the subscripts are the smallest possible whole numbers that reflect the ratio of moles.

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 relative amounts of each element, typically expressed in grams, and is calculated by converting these masses to moles and simplifying the ratio.

Molar Mass

Molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). It is essential for converting the mass of an element to moles, which is a necessary step in determining the empirical formula. For example, the molar mass of calcium (Ca) is approximately 40.08 g/mol, and for nitrogen (N), it is about 14.01 g/mol.

Stoichiometry

Stoichiometry is the area of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. In the context of finding an empirical formula, stoichiometry allows us to calculate the number of moles of each element from their masses, facilitating the determination of their simplest ratio.