32 



BURTON: In other words, you are simply saying that the mechanism of re- 

 action here in water can be to give a hydrogen atom, but in ammonia two solvat- 

 ed electrons have to combine to giveB^. A path must be provided for that to 

 happen. 



ONSAGER: That does not happen. 



BURTON: No, I don't mean it happens in a single process, but a path has to 

 be provided for it to happen. 



ONSAGER: A catalyst has to be provided. You have to make not H but H;>, 

 and you can keep the concentrated solution of sodium for weeks. 



KAMEN: Why isn't the reaction (B) observed in electron bombardment? 

 The required 3 volts could easily be provided. 



PLATZMAN: I believe that it is, but the cross-section is very small. 



KAMEN: Actually all that has been observed (in the vapor) is the H" ions 

 (10). 



ALLEN: Do I understand you think that irradiated ammonia ought to turn 

 blue if it is pure? 



PLATZMAN: More than that. I think irradiated water does turn blue and 

 we just don't see it. 



ALLEN: The fact is that irradiated ammonia does not turn blue enough to 

 see, whereas if you dissolve sodium in it there is no question about it. 



PLATZMAN: It is a question of the recombination time. 



ALLEN: The sodium is the thing that stabilizes it. 



PLATZMAN: No. It is the absence of reactive positive ions. The point is 

 that if you irradiate you have the reactive NH3" 4 " ions. 



ALLEN: In the sodium solution you have just as many positive ions. 



PLATZMAN: But they are of a quite different nature. 



MAGEE: That is an equilibrium process, too, and when the sodium gets 

 hydrated they have essentially no field around them. 



ONSAGER: Very little field. 



MAGEE: This is a steady-state condition. 



PLATZMAN: It is important, in discussions like the present one, not to 

 lose sight of the very great difference between an "electrolytic" ion and one 

 freshly formed -- e.g. , by ionizing radiation. This difference may be brought 

 out by a consideration of the recombination energy of H + and OH" ions. In the 

 gaseous phase, this recombination would evolve about 370 kilocal/mole. In 

 aqueous solution, however, the heat of neutralization is only about 14 kilocal/ 

 mole. What happens to most of the recombination energy? One way to visualize 

 the answer to this question is to consider each electrolytic ion surrounded by 

 its hydration shell, an "iceberg" of frozen water. When the electrolytic H+ and 

 OH- ions encounter one another, most of the recombination energy goes to melt 



