If 0.225 mol of tin combines with 0.450 mol of sulfur, what is the empirical formula of the tin sulfide product?
Well, clearly it is
By definition, the empirical formula is the simplest whole numer ratio that defines constituent atoms in a species. Normally we are given percentages, and use this mass percent to determine the elemental composition. Here, we are explicitly given the molar ratios, i.e.