(Solved): E18B.3(a) Calculate the magnitude of the diffusion-controlled rate constant at \( 320 \mathrm{~K} ...

E18B.3(a) Calculate the magnitude of the diffusion-controlled rate constant at \( 320 \mathrm{~K} \) for the recombination of two atoms in water, for which \( \eta=0.89 \mathrm{cP} \). Assuming the concentration of the reacting species is \( 1.5 \mathrm{mmol} \mathrm{dm}^{-3} \) initially, how long does it take for the concentration of the atoms to fall to half that value? Assume the reaction is elementary.