Cell potential:
Problem:
Drive an expression for the 'operational definition of pH'
Answer:
The Cell potential for the standard buffer can be expressed as
(Ecell )s = E* - 0.0592 (pH)s ... (i)
Cell potential for unknown solution will be expressed as
(Ecell )u = E* - 0.0592 (pH)u ...(ii)
To eliminate E* subtract Eq. (i) from Eq. (ii), we find
(pH)u = (pH)s - ( Ecell ) u - (E cell ) s/0.0591 ... (iii)
Eq. (iii) is the operational definition of pH.