Empirical and Molecular Formula Calculations

Empirical and Molecular Formula Calculation Steps

1. Find Mass Percent: divide mass of component by total mass of substance and multiply by 100%.

1. Find Mass of each Element: assume a 100g sample so percentages convert directly to grams.

1. Find Moles of each Element: divide each mass by the element's molar mass.

1. Find Mole Ratio for Empirical Formula: divide each mole quantity by the smallest mole value obtained.

1. Determine Empirical Formula: write out whole-number mole ratios as subscripts.

1. Calculate Molar Mass of Empirical Formula: multiply number of atoms by molar mass for each element and sum them.

1. Determine Molecular Formula Scaling Factor: divide given molecular molar mass by the empirical formula mass.

1. Multiply Empirical Formula Subscripts: multiply each subscript in the empirical formula by the scaling factor.