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 $S n {S}_{2}$. Why?
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. $S n : S , 1 : 2$.