How do you determine the empirical and molecular formulas of a compound?

The empirical and molecular formulas of a compound are determined by using the compound's percent composition and/or its mass spectrum. The empirical formula gives the lowest whole-number ratio of atoms in a compound, while the molecular formula gives the actual number of atoms of each element in the compound. Here are the steps to determine the empirical and molecular formulas of a compound:

Step 1: Determine the mass of each element in the compound. This can be done by either finding the percent composition of each element in the compound or by using the mass spectrum of the compound.

Step 2: Convert the mass of each element to moles. This is done by dividing the mass of each element by its molar mass.

Step 3: Determine the empirical formula. The empirical formula gives the lowest whole-number ratio of atoms in a compound. To determine it, divide each mole value by the smallest mole value. If necessary, multiply each ratio by the same number to get whole numbers.

Step 4: Determine the molecular formula. The molecular formula gives the actual number of atoms of each element in the compound. To determine it, divide the molar mass of the compound by the molar mass of the empirical formula. Then, multiply each subscript in the empirical formula by this same factor.