Proton affinity of water

Abstract

By employing elevated pressures in the ion source of a quadrupole mass filter, it is shown that D3S+ does not transfer a deuteron to D2O and that D3O+ transfers a deuteron to D2S. Studies were carried out in most instances under conditions where the reactant ion undergoes 30-60 collisions before reacting. Thus, most excess energy should have been removed. The transfer of deuteron from D 3O+ to D2S appears to go to equilibrium with an equilibrium constant of 14.4 which corresponds to a heat of reaction of 1.8 kcal/mole. From this we deduce the proton affinity of water to be 168 kcal/mole.