particular ion. Figure 8.8 shows an ion-specific electrode. For the most part,
they resemble pH electrodes, so care should be exercised to identify the exact
ion an electrode detects.Example 8.8
What is the pH of the solution phase of a hydrogen electrode that is con-
nected to an Fe/Fe^2 half-reaction if the voltage of the spontaneous reaction
is 0.300 V? Assume that the concentration of Fe^2 is 1.00 M and all other
conditions are standard.224 CHAPTER 8 Electrochemistry and Ionic Solutions
Figure 8.7 Electrochemistry is the basis of pH
measurement by instrumental means. Shown here
is a glass pH electrode, whose Evalue is sensitive
to the concentration of the H^ ion.
Figure 8.8 H^ is not the only ion whose con-
centration can be measured electrochemically.
Shown here is a different ion-specific electrode.
All of them use the instantaneous Eof some elec-
trochemical process to determine the concentra-
tion of the specific ion.
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