248 THE REALITIES OF MODERN SCIENCE 



These ions do not appear as vapor, for their existence is 

 due to the potential energy of the systems which they 

 form with the molecules of the solvent. The kinetic 

 energy which would be required to move one of them 

 beyond the influence of the molecules of the solvent is 

 greater than that corresponding to the energy required 

 to produce an evaporation of the solvent molecules. 1 



(4) At the instant that the ions neutralize, normal 

 electronic groups are formed, atoms in this case of 

 hydrochloric acid. Such neutralization means a new 

 configuration of electrons. The hydrogen atom is 

 therefore in a condition of changing electronic con- 

 figuration which renders it peculiarly adaptable to the 

 formation of larger aggregates. The aggregate formed 

 by two such nascent hydrogen atoms appears to be 

 very stable. Diatomic molecules are the product of 

 the neutralization. These are the H 2 molecules which 

 we know as hydrogen gas. A similar formation of C1 2 

 occurs at the other electrode. These gases are not 

 especially soluble at ordinary pressures and temper- 

 atures, and therefore they rise as gases above the 

 liquid surface. 



That there is an electrolytic dissociation we have 

 reasoned from our knowledge of the mechanism of the 

 conduction of electricity. Historically, however, the 

 proof of the dissociation was largely the result of 



1 The latter evaporate rather than the ions of the solute. If 

 the temperature is increased the solvent molecules evaporate more 

 rapidly, and after a time the concentration of the solute ions be- 

 comes such that normal molecules of the solute are formed in greater 

 numbers each instant than they are dissociated. The result is a 

 decrease in the total average number of ions in the solution, until 

 finally when all the solvent is evaporated the original solute is left. 



