When a molecule condenses, it gains kinetic energy which is dissipated by collisions. There is then the possibility that a condensing molecule may kick out a molecule in the interphase or in the liquid. There has been reported a strong correlation between condensation and evaporation fluxes. This "molecular exchange" effect is modeled by assuming that certain molecules that condense, kick out one molecule each. In this paper the influence of the molecular exchange mechanism on the condensation coefficient is discussed and it is shown that under certain assumptions, molecular exchange has no effect on gas-kinetic calculations of phase change. However, an expression suitable for molecular dynamics simulations of the fraction of condensing molecules that induces molecular exchange is also derived.