Theoretical Activity-Coefficient Expressions into a Testable Form

Conversion of Theoretical Activity-Coefficient Expressions into a Testable Form 

Individual ionic-activity coefficients are experimentally inaccessible (Section 3.4.3) hence, it is necessary to relate the theoretical individual activity coefficient/- 

At this stage, the Debye-Hiickel expressions (3.60) for and/ can be introduced 

Since the solution as a whole is electroneutral, v z+ must be equal to v z and therefore 

Prior to the Debye-Hiickel theory, had been empirically introduced by Lewis as a quantity of importance in the treatment of ionic solutions. Since it quantifies the charge in an electrolytic solution, it was known as the ionic strength and given the symbol I 

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