In the course of research, a chemist isolates a new compound with an empirical formula C3H3O2. 2.51 g of the compound when dissolved in 100. g of water produces a solution with a freezing point of -0.325°C. What is the molecular formula of the compound? (For water, Kf = 1.86°C/m.) (For your answer, enter the integer that tells the number of multiples of the empirical formula present in the molecular formula.)