What is the first step in finding an empirical formula?

The first step in finding an empirical formula involves assuming a specific amount of the compound, typically 100 grams. This assumption allows for straightforward calculations of the number of moles of each element based on their individual atomic masses. By using 100 grams, the mass percentages of the elements are directly interpreted as grams, simplifying the conversion to moles through division by their respective atomic weights.

Once the moles of each element are calculated, the next steps involve determining the simplest whole number ratio of these moles, which ultimately forms the empirical formula. This method is preferred because it standardizes the calculations and avoids complications that might arise from variable sample weights or compositions.

Other options either do not facilitate the straightforward calculation needed or employ methods that are not standard practice for deriving empirical formulas. For example, assuming a different mass than 100g or using only the number of atoms without accounting for their respective masses would not provide an accurate empirical formula representation.