This talk will describe recent work in my group by Brian Radak, Scott Yockel and Dongwook Kim concerned with modeling the dynamics of reactions at the gas/liquid interface using a QM/MM approach. The reactions involve atomic oxygen and atomic fluorine collisions with liquid squalane, which is a hydrocarbon polymer, at hyperthermal energies (0.5-5.0 eV). The QM/MM model involves use of the MSINDO semiempirical Hamiltonian for the QM part, and the OPLS empirical force field for the MM part, with QM/MM calculations being done within the framework of the ONIOM model. In all studies, we have calibrated the accuracy of the electronic structure model by comparison with coupled-cluster results for similar gas phase reactions, and we have in some cases done direct dynamics studies of the gas phase reaction dynamics for reference. Detailed comparison with beam/surface measurements are provided. These studies provide new insights about the role of liquid interfaces in governing reactive collisions. They also demonstrate how dynamical processes may be described for condensed phase systems in which several bonds may be broken or formed in a series of chemical reactions all within a single simulation.