KINETICS OF THE REACTION OF SOLVATED ELECTRONS WITH WATER IN LIQUID-AMMONIA

Solvated electrons ( less than 10** minus **6 M) produced by flash photolysis in ammonia react with water according to the rate law d left bracket e** minus right bracket /dt equals k multiplied by (times) left bracket e** minus right bracket multiplied by (times) left bracket H//2O right bracket with the rate constant k equals 0. 16 plus or minus 0. 03 M** minus **1 at minus 40 degree C. The rate law is compatible with the reaction e** minus plus H//2O yields H plus OH** minus , but the activation energy E//a(e** minus ) equals 6 plus or minus 1 kJ/mol is too small for this endothermic process with DELTA H**0 equals 52 kJ/mol. The observed kinetics suggest that the solvated electrons are still the only reactive species in these solutions; but their concentration is lower than the metal concentration by many orders of magnitude due to the well known spin pairing equilibrium, which must include a metal cation and a solvent molecule.