Answer
It is possible for two substances with the same empirical formula to have different properties because two compounds with the same simplest ratio of A atoms to B atoms can differ when it comes to the total number of A atoms and B atoms that each has.
Work Step by Step
The total number of A atoms and B atoms in a given compound contributes to its physical properties, not the ratio of A atoms to B atoms. Thus, if two atoms have the same empirical formula, AB, their molecular formulas are AB and A2B2 respectively, the physical properties of the two compounds will differ from one another.