In reactive exothermic collisions (A+B-->C+D) masses of the reactants change after collision and some heat is released. Let's assume that the heat released is used in accelerating products (i.e. C and D). How can we compute the post-collision velocities of C and D such that the momentum is conserved. Please note that the masses of C and D are not the same as masses of A and B, however, their sum is.